'^ T ^ ^55 .I\g ^^^^^iSTnnl^frtM^Hf^jSlaf^^n?^ ^J Structural DRAFTING^ DUFOUR SCHOOL -if CO HICAGO 1 L NDEMCE Class Jl^i)_§ Book ^ \ '^ COPYRIGHT DEPOSITS STEUCTUEAL DEAPTING A PRACTICAL PRESENTATION OF DRAFTING AND DETAILING METHODS USED IN DRAWING UP SPECIFICATIONS FOR STRUCTURAL STEEL WORK By FRANK O. DUFOUTl, C. E. "ASSISTANT PROFESSOR OF STRUCTURAL ENGINEERING, UNIVERSITT OF ILLINOIS ILLUSTRATED CHICAGO AMERICAN SCHOOL OF CORRESPONDENCE 1913 T "B 56 Copyright, 1912, 1913 by American School of Correspondence* Copyrighted in Great Britain All Rights Reserved ^A^ ICI.A350056 CONTENTS PAGE Drafting room equipment and practice ^ 1 Classification of drawings 1 Drafting — room personnel. 2 Assignment of work 3 Records 4 Drafting materials 6 Stress sheet 11 Layout 12 Allowances for planing and cutting .• 15 Allowances for pin material 15 Allowances for bending 16 Shop bills 17 Detailing — General instructions 35 Lettering 35 Abbreviations 39 Dimension and material notation 40 Rivets and rivet spacing 45 Bolts, nuts, and washers. . * 54 Tension members 57 Clearances 59 Detailing methods 65 Detailing of angles 65 Detailing of plates 66 Detailing of, combinations of structural shapes 71 Detailing of beams 72 Detailing of roof trusses. . .■ 81 Detailing of plate girder spans 87 Detailing of compression members Ill Detailing of built-up tension members ". . 112 Facilitation of erection 112 WOOLWORTH BUILDING, NEW YORK CITY One of the Most Conspicuous Examples of Modern Fireproof Construction. Taken from the Municipal Building The View la INTRODUCTION A STEEL skyscraper, like the fifty-five story Woolworth Build- ing in New York, is an architectural and engineering triumph and its erection is a never-ending source of interest and wonder to the spectator. Throngs of interested persons are always standing near while the giant derricks raise the columns and girders aloft, swing them into place, and leave them to be fastened securely by the men with w^hite hot rivets and pneumatic hammers. And yet in all the confusion of noise and bustle of the workmen, the control of the engineer with the blue detail sheets before him is in evidence. Every piece of steel has a certain place in that great structure and, although made miles from the scene and possibly in different mills, every piece fits exactly down to the rivet holes. The skeleton grows before your eyes, a potent illus- tration of the might of minds, of the value of accuracy of detail and organization of mechanical forces. ^ Do we not too often, in the midst of our wonder and apprecia- tion of this marvelous work of man, forget from whence all this order and system sprang? Do we not lose sight of the careful calculation of the size and thickness of every angle, plate, and girder, the location of the holes, and the number and size of the rivets to be used? When we think also of the checking and recheck- ing of all the calculated results in order to avoid mistakes in dimen- sions and in order to make sure that no structural member is to be called upon to bear strains beyond its strength, we begin to see how it is possible for a whole building to be put together without one alteration, without one single piece being sent back to the mill. The man who stands boldly on a swinging girder and looks down from dizzy heights to the throng below is a very unimportant INTRODUCTION man compared to the designer, the detail man, the checker, and the steel mills' superintendent, who carry the work safely and accurately to a finish. ^ The author in this article has spoken from a wide experience in this line of work and his practical instructions regarding drafting methods, systems of costs, record sheets, and the detailing of the elements of structural steel will be found of exceptional value to every trained and untrained man. It is the hope of the pub- lishers that the work will be of service to a wide circle of students and general readers. HOTEL LASALLE, CHICAGO Holabird and Roche, Chicago, Architect,. Gtortp. A. Fuller Company, Contractors, Chicago BLACKSTONE HOTEL, CHICAGO, IN PROCESS OF CONSTRUCTION This Fireproof Hotel Is of Steel and Tile Construction Throughout, with Brick Exterior. Marshall & Fox, Chicago, Architects. Geo. A. Fuller Company, General Contractors STRUCTURAL DRAFTING PART I DRAFTING ROOM EQUIPMENT AND PRACTICE Introduction. Structural drafting may be defined as the art of making drawings of certain objects and placing thereon dimen- sions and other notes which when taken together will convey the necessary information for the manufacture and in some cases the erection of the structure under consideration. In the making of these drawings great accuracy in drafting is not necessarily required. The chief requisites are that the letter- ing and dimensions should be so clear that no misunderstanding is possible. Dimensions not given should never be scaled by the draftsman or workman, but the actual value should be ascertained by consulting some one familiar with the work. Classification of Drawings. The classes of drawings which are made in a structural drafting room are: the stress sheet; the assem- bly, or general detailed, drawings; and the shop drawings, or, as they are more often called, the detailed drawings. The stress sheet is a tracing upon which is usually shown a skeleton outline of the structure upon the lines of which are marked the stresses which are caused by the traffic or other forces to which the structure is subjected, and also the size and shape of the mem- ber designed to Tvdthstand these stresses. The assembly or general detailed drawings usually give several views of the structure as it appears after it has been erected. On these views are shown to scale the members as they appear in the finished structure together mth all the rivets and other details necessary for its completion. The overall dimensions are usually given and also any other dimensions which are necessary for the draftsman to complete the shop drawings. While the size of the members and their connections, as well as the number of rivets Copyright, 1912, by Americin School of Correspondence. 2 STRUCTURAL DRAFTING required, are always given, yet in a few cases the length of the member or shape and the individual spacing of the rivets are also given. The shop drawings, or detailed drawings as they are more often called, consist of views of a certain member of the finished structure so dimensioned that it may be constructed by the men in the shop. It requires greater skill and more experience to make the assembly drawings than it does the detailed drawings, but in each case the men must be familiar not only with the drafting prac- tice but also with that of the mill and the shop. Drafting=Room Personnel. A drafting-room force consists of an engineer, a chief draftsman, squad boss, checkers, draftsmen, and tracers. The engineer has charge of the plant as well as of the drafting room and is directly responsible for the ordering of all material, the manufacturing of the structure and its shipping to the place of erection. He conducts the correspondence, keeps track of the work in the drafting room and in the shop, and, in case his plant is one of many of a large corporation, makes weekly or monthly, reports to his superior officers. In case his plant is a small one, the en- gineer usually does most of the work of designing and estimating. The chief draftsman is directly responsible to the engineer for the getting out of the detailed plans or shop drawings and also ordering of the material. The squad boss reports to the chief draftsman and his duty is to keep track of and to get out the drawings of any particular struc- ture which is assigned to him by the chief draftsman. The squad bosses usually have from three to four to as many as twenty drafts- men under them, according to the magnitude or the number of structures which they are responsible for. In addition to the draftsmen are the checkers, certain men usually of great experience in matters relative to mill and shop as well as drafting-room practice. It is the duty of these checkers to go over the draftsmen's work, see that all errors are corrected, and then finally sign it as approved. The checker only is held re- sponsible for mistakes which then may be left upon the sheet. The tracers are for the most part young college graduates or apprentices, and their office is simply to trace the drawings which are handed to them by the draftsmen. STRUCTURAL DRAFTING 3 A fireproof vault is always a part of the equipment of every well-equipped drafting ofiice. In it are kept the notebooks in which the computations necessary for the design and detailing of the structures are kept, and also the tracings which have been made in the drafting room. In case the drawing of any particular structure is required, the tracing is taken out of the vault, blue prints are made, and the tracing returned as soon as possible. The vault should be so equipped that whenever the door is opened the interior becomes lighted. Aside from the mechanical convenience of this arrange- ment, it avoids the possibility of any person being accidentally locked in, since the rule is that in case of fire the vault should be immediately closed by the one nearest to it. Assignment of Work. When the engineer of the plant received a stress sheet from his head officer or from the designing depart- ment in his o^Ti work, he hands it to the chief draftsman. The chief draftsman makes a record of it and gives it to the squad boss who is most accustomed to that class of work. The squad boss in turn hands it to the checker or checkers and these men make details for the various parts of the structure and make layouts for the various joints. The engineer now^ orders the material which will be required to build the structure or assigns a checker to do so and then returns the stress sheet to the squad boss who assigns certain draftsmen to prepare the shop drawings for the structure. Draftsmen make the drawings and turn them over to the tracers to trace them. After the tracer has finished the tracings of the sheets, he passes them to the checker who in the first place made out the details and layout and ordered the material. The checker goes over these trac- ings very carefully and sees that all dimensions are correct, that all material used is that which he ordered, and if the drawings are correct he signs his name to the sheet. If the dimensions or any other matter upon the drawing is found to be incorrect, the checker places a ring around it with his blue pencil which is used in check- ing and off to one side places the correct value. After all the apparent errors have been corrected in this manner, a consultation between the checker and the draftsman who made the drawing is held. The errors are pointed out to the draftsman who in turn checks the work to prove the checker's results. The draftsman then takes the drawing and makes the necessary changes and returns it to the checker. 4 STRUCTURAL DRAFTING Great care should be taken in making the changes that no dimensions or other notations \\Titten upon the drawing by the checker are rubbed off. The checker then examines the drawing carefully to see that all the errors which he has pointed out have been corrected. He then cleans the tracing, signs his name to it, and returns it to the squad boss. The squad boss in turn has the necessary blue prints made and turns the tracing together with the prints over to the chief draftsman, who in turn files the tracing in its proper place and gives the blue prints to the engineer of the plant who sees that they are distributed to the foremen of the various shops where they are required. Records. A job is known by the order number which is given it when it comes into the hands of the engineer of the plant. This order number should go on all papers upon which anything con- cerning that structure is placed. Failure to do this will result in great confusion and much time will be lost. The penalty for persist- ent failure to comply with this very important method of procedure is usually dismissal. Since the draftsman, or in fact any of the office force, may work upon more than one order during the day or week, and since it is important that the cost of the drafting or engineering work for any particular order should be known, it is essential that the men keep time cards upon which the order and the time placed upon that order is noted. Usually fractions of an hour less than one-fourth are not reported. Fig. 1 shows one of these time cards upon which is noted the work of a checker for one week. It shows that he has worked upon several orders and also shows the exact amount of time he has placed upon each one and also the rate per hour which he received. In this way it is possible to obtain the cost of engineer- ing of any particular order when it has finally been finished. An orderly record of the passage of the work from the time the stress sheet enters the engineer's office until the material has been shipped, and also a record of the progress of the work during erection, should be kept. This is usually kept on 3X5 cards in the engineer's office. In addition to this card-index record, a monthly report in blue print form is kept showing the progress of the various orders. For instance, the progress report would contain such items as these: Order received, layouts made, material ordered, detailed sheets FORM & NAME E I53-^0M-10-^2-03 ENGINEERING DEPARTMENT .J./l. Frost- RATr ^0 TIME CARD FOR WEEK ENDING ./iM [.gujLjJ_ 190.4 ORDER CD c o 5 0) 1- Wed. Thur. -ii_ en Sun. Tue. Wed. c 3 f^ L_ It) TOTAL HOURS COST Nunnber iDiv. ^4F^\ 6 4\3lA 6' 23^ B4I5^ 5^4i 6 43j 25^ . ' \ 1 Estimatinq General Holiday Total '¥:¥ 4 8 4 51 Sick ! 1 ■ 1 4 4 Vacation i 1 1 Out Total '///^//// d 11^ 4 55 HOURS WORKED P.L.^-. " Al 1 OWED ('not wor ked - " PAID FO R.. i — - ?..^ 'i Fig. 1. Draftsman's Time Card Showing Hours Spent on Order Indicated STRUCTURAL DRAFTING finished, shop bills made, templet work finished, work fabricated, work shipped; and in addition to this progress report, which is made cut in the office, is the report of the erector on a job in the Fig. 2. Side View of Drawing Board, Having Elevating Pegs field. The erector's form of report contains such headings as tend to indicate the progress in the false work; the erection of the trusses and floor system; and the amount of field riveting and painting completed. Drafting Materials. Instruments. The drafting instruments required are : A drawing board, T-square, triangles of various kinds as noted below, pencils, scales, erasers and erasing shields, a set of drawing instruments, a large linen cover, and half sleeves. The drawing board should be made of soft pine with battens upon the back in order to prevent the warping of the board. Since few drawings in structural engineering are larger than 24X 36 inches, it is not necessary to have the drafting board larger than 26X38 Fig. 3. 45° Triangle with Cope and Beam Beveb inches. A drafting board should not lie close to a table, but should be raised from the table by small legs placed at its upper edge as indicated in Fig. 2. The T-square should be about 40 inches in length and should be of good quality wdth an amber edge upon each side. The amber STRUCTURAL DRAFTING 7 edge is of great advantage since it will allow the draftsman to see lines below that one which he is drawing and, therefore, prevent him from overrunning by drawing one line past its limiting point. Such a T-square may be procured for about S2.25. The triangles should be of amber or celluloid, and should con- sist of the following: One 45-degree triangle with 10- or 12-inch sides; one smaller, say with 6-inch sides; two 60-degree triangles with 10-inch sides; and two mth 4-inch sides. One or more of these triangles should have the beam and coping bevels fixed upon it as in Fig. 3; this will have to be done by the draftsman, since no such triangles are on the market. The pencils used by the draftsman should be such as \\ill make clear and black lines upon paper in case the drawing is to be traced. If the drawing is not to be traced, a harder pencil will suffice. In case a drawing is made directly upon tracing cloth, a soft pencil should be used and it should be kept sharpened. This will neces- sitate frequent rubbing over the sand paper pad which every drafts- man should have close at hand in order to keep a good point upon his pencil. The pencil recommended for detailing where a tracing is to be made is 'Tvoh-I-Xoor, 3 H," although some draftsmen prefer 4 H or 5 H. The latter are, in the writer's opinion, to be recommended for detailing where a tracing is not required from the original. In case drafting is done directly upon tracing cloth, a 2 H pencil is the correct one to use. A red pencil should be kept for marking upon blue prints and a blue pencil for making checks on tracings. Never use a red pencil upon tracing cloth, since it will not be easy to erase, whereas the blue-pencil mark may be washed off with gasoline or erased with a pencil eraser. The scales required are the architect's and the engineer's. The former has certain divisions upon it and each of these divisions is divided into twelve parts which indicate inches, and these parts are in turn divided into halves or quarters or other small divisions denoting the fraction of the inch. The architect's scale which best serves the purpose is the one which has the 2-inch, 1^-inch, 1-inch |-inch, f-inch, |-inch, |-inch, |-inch, i^-inch, and ^-inch scale. A special scale for the making of drawings to a large size or for the making of layouts is a great convenience. Such a scale is on the 8 STRUCTURAL DRAFTING market and is divided so that half of an inch is equal to one inch. This scale should be in the outfit of all checkers. The engineer's scale is one on which the inches are divided into certain decimal divisions. The best scale for this is that which has its edges divided into 10, 20, 40, 50, and 60 parts of an inch. This scale is of use only in laying off bevels and natural functions of angles or in draw- ing outlines upon which details will be constructed with the use of the architect's scales. The tendency of young engineers to use the engineer's scale, allowing a certain decimal to equal a certain fraction of an inch, is to be discouraged because of the liability of error, and a severe penalty imposed for a second offense. Care should be taken in the use of scales such as the architect's which have different scales on the same edge in order not to get the feet which belong to the wrong scale. A small paper clamp should be attached to the scale a short distance from the center opposite the end where the scale which the Fig. 4. Triangular Boxwood Scale, with Scale Guard or Clamp in Position draftsman is using is situated. This will prevent the scale from being turned over, hence avoiding any other scale, but the one the draftsman is using at the time, turning up. Also when the draftsman picks up the scale by the paper clamp, the end on which the scale he is using is situated will tilt downward and at once indicate to him which end he should place in position to measure what he wishes. Fig. 4 shows one of these clamps in position for the scale as indicated. A good ink eraser, together with a metal sheet called an eraser shield in which are various shaped holes, is an indispensable adjunct of the draftsman. In all cases where it is necessar}^ to erase, the ink eraser and the shield should be used. Never use a knife to erase STRUCTURAL DRAFTING 9 either upon a paper or upon a tracing cloth, for no matter how sharp the knife is, the sheet will be rubbed and ink will not run smoothly upon the place so worked over. A good soft rubber may be used for erasing pencil marks upon either the paper or the tracing cloth, although benzine, turpentine, or gasoline is much better for erasing pencil marks and cleaning off other dirty spots on the tracing cloth. Care should be taken to investigate the status of the insurance and fire laws on this point, since in many cases it is not allowable to use such inflammable materials in houses of the character of the draft- ing office. An expensive set of instruments is not necessary in order to do good drafting. A good pen, a bow pen, a pair of dividers, and a compass with pencil and pen point, are all that are necessary. In many cases it is advisable to have two or more pens, one of which should be quite large, one medium, and one rather small. Many good drafting inks are sold in the open market, and it is no longer necessary for the draftsman to make his own ink by combining India ink with water. In fact this is a distinct disad- vantage, since many of the drafting inks on the market are water- proof and while tracings should not be placed so as to become wet, nevertheless it is quite an advantage to use waterproof ink upon them, so that in case they should be accidentally wetted, it will not injure them so that they can not be used. A sheet of cambric of dark color the size of the drafting board or better still the size of the entire table and drafting board should be used to cover up the work when no one is working, since dust accumulates very readily upon the drafting board and produces much undesirable dirt and, therefore, a very dirty drawing. It is also advisable upon starting work in the morning to brush off the desk and drawing board and to wipe off the T-square and triangles with a cloth. This will prevent dirty marks appearing on the draw- ing when they are first placed upon them. Detail Paper. Detail paper is the paper upon which a drawing is made before it is traced or upon which drawings are made to be used by the detailers in making up the details of the structure. Detail papers should be of buff color in order to prevent the showing of dirt upon them too easily, and also to be restful to the eye, and they should present a surface which will take a pencil or ink mark equally 10 STRUCTURAL DRAFTING well, and the}' should not be so thin that they will not stand a great amount of erasing. ]\[any good papers may be bought in the open market. They may be purchased in sheets of a desired size or they may be purchased in rolls of a certain weight, and any width. When sold in sheet form they are usually sold by number of sheets; when sold in roll form, by weight. 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DIAM OF BOLT D LEMGTh B SCREW LEMGTH OP BOLT WASHER REMARKS kEriGTH M DIAM. u DIAM. w THICK T Fig. 19. Shop Bill for Turned Bolts o h uJ I > z o O u Q GQ y z -I < o z: Q cr O en _) si --|(VJ © "iO|° "to 5 II I I Li- H O !±J O Q. O CL o ^D U. < r O _j UJ I, ^5 cQ X O u. o Ll. O u u. -I O ^ z: o 7L O 00 ^_ 10 ^ z: o q: o M S K ^ CQ ^ ^ \ \ \ r < 1 \ 1 Q U Q. ' 1 1 (0 < ) i 1 ' 1- u r o ^ U i i i o z i 1 1 ZL ft: 1 1 1 , _J l- ^ 00 < Li_ to 1 ■ 1 ' Q ^ •-ITl iC 1 1 1 UJ or 5;^ 0^ O 1 1 1 1 ' 1 1 1 1 ■' ' 1 Ul Q a: O a? ^ z: o o ^ - ^^ K 1 I 1 UJ \ \ N^ i ! '' tn ^ ^ li_ 01 O '^ t ' . 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' 1 o 'I 1 ^ ^ CQ DC u ^ C UJ < LU i' ' < [ 1 D i^ ^ O -z. z: ) '■ O wj 2 61 ^ ^j ^ ^ ^J 5 < Q U (1 f- < o Q: CQ < iC o 5 to en or < CO t u ^ t? z j; V - < UJ O UJ 1 ^ ^ fVj i z: z: o o to ^3 ; ^ ^ CO 5 ^ --J 2 O UJ o UJ § ^ "^ ' ^ ^ •^ ^ ^ Q _i 0- •^Qti !Ql^ •^1^^ -1^ •^ICQ ^ic^, ^1^ "^"Vj ^ItVj ^'Oj < ir z: D^ ui DC ii_ < '^Kj:, 5 :^ ^ ? -kVj ^x^ - =: f p Q cr D 1- o UJ < r o h Q ZI o UJ z (0 1 3 o o cr CL li- O 0) _J 'a: o 1- () 1- a. o in i2l (0 ? ^ i * CO - = > ft UJ u 5 Q o 5 III q: u a: < < or i^ f^ O z: z: lij i8 CO ^ ^ fVj ^ ^J ^ oo ^ a Saline Bridge Companv OrderNo 5heet INo CO 1- o DO o z < lO 1- liJ > a: 1- j o CQ (JO :^ < ULl ^ O aJ in I - § X 2 < Q cr Q uJ llI CD a z: ^ (X LiJ H- z: o e^ if) \- U > cn 10 a: < z uJ fe S d 21 > < LU O _l - < Q a: Q UJ LiJ CO cr ii < Q_ in h u > or < UJ or H 0^ 5 ^ Q U S I- < Q . STRUCTURAL DRAFTING 33 OROtK Assigned to Name of Structure Name of Purchaser Ship to Ship Via .Plant SHIPPING BILL (RIVETED WORK) WoRn Fabricated at Plaint MEMBER rio REQD rSAME MARn SHEET MO MATERIAL DESCRIPTIOM. FEETlt1CHE5 LLMGTH CALC. WT. OriE PIECE TOTAL SHIPMENT DATEL^^^'g^REMARKS WEIGHT iiai ■■I ■■ 3 Fig. 24. Shipping Bill ORDER NO. Saline Bridge Company ^ MEET No. .BRANCH MAKE MARK Fig. 2.5. Shop Bill for I-Beam3 34 STRUCTURAL DRAFTING ORDER ASSIGNED TO NAME OF Structure Name of Purchaser Saline Bridge Company work fabricated at Plamt Plamt Fig. 26. Shop Bill with Blank Space for Sketchy' Saune Bridge Company Change Order Please Make the Following Changes CHANGE FROM TO ITEM NO KIND SIZE LENGTH n. IN. MARK SKETCH NO NO KIND SIZE LCNGTh FT. IN. MARK SKETCH m 1015 10 / 8"x^0.f 17 10^ 6 / 8"x^0.5'' 17 lOi -_ -^-^ .^ . ^- L,_> \ — J J ■ ^ ^ — ' — — ' — T 1 1 1 r^ — ^ r^^— 1 r .-^ — 1 1 ^ finished Materia SURFACES IN PIN HC L -. 3LE5 ARE COATED WITH WHITE LEAD AND TALLOW BEFORE SHIPMENT.. Sp :ciF ._ Made by.. i9.. Pa NT _ - - - - - - - ^^ ..IN Charge of 13 Fig. 27. Sheet Used for Change of Order STRUCTURAL DRAFTING 35 DETAILING— GENERAL INSTRUCTIONS Lettering. In order that the drawing may give the necessary information and that no mistakes should occur in the reading of the drawing by the shopmen or others, it is necessary that the letters and dimensions upon the drawing be made so that they are exceed- fl'ji'n'aof Fig. 28. Method of Constructing Parts of Small Arc-Line Letters ingly clear. In order to save time in lettering, an alphabet should be used that can be made quickly and easily. The alphabet which is known as the straight-line alphabet fulfills these conditions. It ntya Fig. 29. Method of Constructing Parts of Small Arc-Line Letters is made b}^ one of the characters or by a combination of the char- acters shown in Fig. 28. A study of Fig. 29 will show that the general scheme of this system consists of the oval and the straight line. The slant at which these letters are made is a very important factor in a drawing, the proper slant being 3 in 8, as shown in Fig. 30. Even a slight in- crease, however, will give one the im- pression that the letters lean too far forward and it will spoil the appearance of a drawing otherwise good. The height of the lower part of the letter should be equal to two-thirds or more of the total height. Figures should be of the same height as the capital letters. The total height of the small letters should not be less than one-tenth of an inch. This makes Fig. 30. Method of Constructing Parts of Small Arc-Line Letters 36 STRUCTURAL DRAFTING the capitals three-twentieths of an inch high, not less. The reason for adopting this height of letters is in order that, if necessary, ordi- nary tracings may be reduced for publication and the letters will then show up clearly. Fig. 31 shows the complete alphabet and at c d'^fgi'hijik'hm'rfopqf ill ill -r^ll ill I— I' -?■" -7" If-" 1 1 2 1 5 5 Z 15 8 4 5 2 8 4 .8 16 Fig. 31. The Completed Letter, with Arrows Showing Direction of Stroke the numerals from 1 to 0, also several fractions. The fractions should never be made less than one-tenth of an inch in height for each of the members, and the dividing line should be horizontal, never slanting. Fig. 31 also shows by means of small arrows the direction the stroke should take when making the different letters and figures. There is a tendency to make several of the letters and figures as shown in Fig. 32. This tendency should be carefully avoided, special attention being called to the turned-up ends of the members of different characters. Care should be taken not to get the upper part of the s and the 8 larger than the lower part. If this is done or if the two -p ^y^ >X O-. -L CT^ ^^~^ /-N parts are made ^ / Lu J y^ / J equal the upper -^ ^"^ will appear to be much larger and these char- acters will look Fig. 32. Example of Poorly Constructed Letters OUt 01 propor- tion. The capital letters /S, G, E, F, P, and R, and the figures 2 and 5, present some difficulties. These characters are shown in Fig. 33, and may briefly be commented on as follows: STRUCTURAL DRAFTING 37 Letter S. The letter S should begin at the point 1 slightly inside of the circumscribed parallelogram. The line should then be tangent to the top and should come slightly inside of the further side at point 2, It should then cross the center line above the middle height at the point 3 and be tangent at point 4 and point 5 as indicated. Letter G. The letter G should start at the right side of the parallelogram and be tangent to the top, left side, and bottom as well as the right-hand side where it extends upward to a height of one-half of its total height before the horizontal line, which should extend one-half of the distance across the letter, is drawn. Letter E. The letter E presents no difficulties other than a central horizontal line should extend about two-thirds of the distance Fig. 33. Proportion and Slant of Capitals across the letter and should be at an elevation of two-thirds the height. Letter F. The letter F is but a part of the letter E as indicated. Letters P and R. P and R are constructed on the same general principle. The upper part of both letters should be at least one-half or more of the total height, and in the case of R the lower right-hand stroke should not extend further than the right-hand side of the circumscribed parallelogram. Figure 2. The figure 2 is constructed by starting at the left- hand side of the circumscribed parallelogram and continuing tangent as indicated in the figure at points 2,3, and 4. The lower part 4 — 5 38 STRUCTURAL DRAFTING should in all cases be horizontal and it should never extend further than the right-hand side of the circumscribed parallelogram. Figure 6. The figure 6 should start at the point 1 and extend downwards one-third of the total height. The lower part of the figure should then be drawn, being tangent at point 3 and 4 and slightly curled up at 5 where it should extend a little further to the left of the upper part. The horizontal part 1 — 2 should not extend quite up to the right-hand side of the circumscribed parallelogram. In all cases where inch or foot sizes are employed, they should be made clearly and regularly and should be not less than one- twentieth of an inch in length. Letters and figures should always be made by beginners by first preparing guide lines drawn with a pencil. Even in case the Fig. 34. Guide Sheet for Obtaining Correct Slant in Letters guide lines have been drawn upon the detailed paper, it is also advisable to draw them upon the tracing cloth, or place under the cloth a sheet similar to Fig. 34, with the lines drawn in ink, to act as a guide. This practice should be continued until enough skill has been acquired to make the letters uniform, without the assistance of more than a line or two. The only manner in which a person can become proficient in lettering is through practice. A piece of paper ruled up and having the slant of the letter placed upon it as shown in Fig. 34 will be found an excellent thing on which to practice lettering. Letters can not be made nicely and quickly as one would suppose. Care and time are required until the draftsman becomes proficient in this respect. STRUCTURAL DRAFTING TABLE IV Abbreviations 39 SYMBOL SIGNIFICANCE L. or Ls. Angle or angles C or Cs. Channel or channels J. oris. I beam or beams Z. or Zs. Zee bar or bars T. or Ts. Tee beam or beams PI.. Pit, or Pis., Pits. Plate or Plates @ at nil. riller Stiff. Stiffeners ri. or rig. Flange r. Rivet fr Field rivets s.r Shop rivets e. Eccentricity C.I. or i Center line o or d) Diameter # Pound or pounds c. to c. or d's Center to center Latt. or La its. Latticed or lattices Lot or Lots. Lateral or laterals olr. Alternate M.PI Masonry plate 5pl. Splice Abbreviations. In the making of drawings certain abbrevia- tions are used in order to save time and for the sake of convenience in many other respects. These abbreviations together with what they signify are given in Table IV. They should 'be carefully studied and should be written close to the material to which they apply and should at least be one-sixth to one-eighth of an inch from the material. Never write dimensions or letters so close to a line that they will interfere with the line. In wTiting dimensions at a con- siderable distance from the piece of material or place to which they apply, an arrow is used to indicate their proper position. In all such cases the arrow head should be at the end of the line which points to the place to which the abbreviation or dimension applies. 40 STRUCTURAL DRAFTING Fig. 35 illustrates some cases and also shows the form which the arrow should take in order to present a good appearance on tlie drawing. Dimension and Material No= tation. Proper Placing. A draw- ing may be said to have been correctly dimensioned when any desired necessary dimensions may be obtained from it without it being required that any dimen- sions should be added or sub- tracted or divided in order to obtain the desired result, and when no unnecessary dimensions are upon the drawing. By nec- essary dimensions are meant those dimensions which are required in order that the material may be fabricated so that the finished struc- -/ P/3 r Fig. 35. Correct Use of Arrow and Line in Dimensioning /Z at 4f- 2L5 5'><5"^T' e — © — © — © — © — © (o) IZ at 4 I ' 2L5 3"x3"x i" Q — ©. © — © ^> (^) ih) -)(- -^-^£>-^-^ ^P^2 5 at 5=1-3" 6' 2L3 5\5fj— V (a) ib) e-r€> l4 ^L^ 3"x3fxi' 4' -e- 9 9 (^ 3' 3" (c) id) Fig. 38. Correct and Incorrect Placing of Dimensions figure showing the wrong construction, of a cross or half cross of a straight or nearly straight line, but should have a gradual slope as in Fig. 37 where it is greatly exaggerated. Dimensions as mentioned above should be placed above the dimension line where possible and the material should be noted so as not to interfere with the dimensioning. Figs. 38a and 38b show good practice and Figs. 38c and 38d poor practice. Sometimes it is necessary to place the dimensions as in Fig. 38c and 38d but never place the material notation as shown in the same figures. Fig. 38b gives the preferable method. 42 STRUCTURAL DRAFTING -© — Q .Q ^'^^^ N^ Q \ O 6 Q Q Q (D) ^ /p. AMien several spaces are equal, the matter may be written as so many spaces at so much is equal to so much, or each space may be dimensioned separately as shown in Figs. 38a and 38b. In case the space is too small to \^Tite a single dimension in it clearly, the dimension may be put at one side and an arrow used to show where it belongs, Fig. 35. ' In writing dimensions the inches should be given as well as the feet, and in case the inches amount to nothing or to a fraction, a cipher should take the place of the inches. It is not necessary when all rivets are shop rivets to draw in each in such cases to put in the end rivets and to inidicate the spacing and every rivet when the spacing is the same. It is only necessary of those which lie between but which are not shown. Fig. 38b illus- trates this. In case of field rivets all rivets must be shown. No de- parture from this rule should be allowed. Fig. 39 is an example of this. It is noted in this figure that although the spacing of many of the rivets is the same, yet all are shown in their proper place. In placing dimensions where two or more members are detailed together, dimensions for the main member should run straight through from one end to the other. The dimensions of the larger member in so far as they are the same as the dimensions for the smaller may be used for the smaller member and additional or subdimensions be placed in con- venient places in order to complete the detailing of the smaller mem- ber. As an example of this see Fig. 38a where the edge distances and the method of detailing should be noted, and Fig. 39 also where the edge distances are the subdimensions. In Fig. 39 two dimen- sions are given at one of the ends. This illustrates two methods of placing the same dimension. The dimension directly under the line of dimensions for the main member is placed in the preferable way. In the placing of subdimensions great care should be taken iiVj 4 O Q Q ^0 t Q -< ) @t Q O i^ Fig, 39. Correct Method of Indicating Shop Rivets STRUCTURAL DRAFTING 43 not to make them too small or to place them so that they interfere with the guide lines of the main dimension. Notation Used. As stated before, the feet and inches should always be given when a multiple space is given. P'or example they should be ^Titten thus: 5 @ &'=?>' -0^' 2 @ 3''=0'-6" 7 @ 4''=2'-4'' In single dimensions less than 1 foot it is not necessary to state the for the foot, and, therefore, we have for example 4", 6'', 11'^ etc., up to and including 12". A dash should always be placed between the feet and inches as shown above. Careful attention should be paid to this detail since the omission of the dash may cause the dimensions to be considered as all feet or all inches and time and money will accordingly be lost. In material notation the following are the rules : For angles the number should be placed first, the angle sign second, the dimension of the greatest leg next, then the small leg, then the thickness, and then the length in feet and inches. For example, 2-Ls 5" X 5' X 8 X IZ'2 For plates the number comes first, the abbreviation next, the width in inches next, then the thickness in inches, and finally the length in feet and inches. For example, I -PI. I8"xi" ^ 2'-4" For beams and channels the number is stated first, next the depth in inches, then the weight in pounds per foot, then the sign, and finally the length in feet and inches. For example, 2-/2" A 51^*^ Is X l8'-2' 5 -7" X 5/^ Cs xl6'-54 Zee bars are designated by their depth and thickness. The number is written first, the depth next, then the thickness, then the sign and finally the length in feet and inches. 39' ^^ 5'' 7" 64 ^ I JOL/ff /6^ / ■ J \^ <:: Ly ^ 64^0aL/3Z^^ I t -i <9 /? I ; ^1 Qo ?" ^ V '""Vi ^ I. I ' • f5 <0 i: I I § Bof/i 5/de5 Otherside This side Both 51 d 63 Ofherside Th/5 side Both sides Ott)er 5ide Til is side * # ^ ^> ~©~ -e-i .1 It V ;::) ^-f- > ■^77777*^ ^y\\^\\' STRUCTURAL DRAFTING 45 For example, 3-6 3" ^ 8 Zs X l4'-d' Bars are designated by their number, then their size, or diameter, and finally their length in inches. For example, 3-1" a X 20'- ^" J -f A 16'- 4f Rivets and Rivet Spacing. Rivets are made in various sizes and are spoken of according to the diameter of their shank. Thus a |-inch rivet is one which has its shank | inch in diameter. The heads of the rivets are not perfect hemispheres, being less in height than one half the diameter of the head. Table V gives the dimen- sions of rivets of various diameters and their conventional represen- tation in detail drawings. These dimensions are desirable on the drawings since they are often necessary in order to so figure the work that the material will not strike the heads. Rivets smaller than f inch are seldom used except where the size of the material requires it. Rivets larger than \ inch in diameter are seldom used except in the heaviest work; and the beginner is advised not to use them until he has permission from those above him. in charge. Rivets should not be placed so close that the material between them is unduly injured by pushing or that the driving tool or "dolly^' v/ill interfere with one rivet when driving the other; likewise they should not be placed so far apart that the material between them will separate or open up. Unless specified otherwise in the specifica- tions Table VI may be taken as good practice; for |-inch, |-inch, and 1-inch rivets, the minimum spacing is seen to be three diameters of the rivet. TABLE VI Minimum Rivet Spacing (All dimensions given in inches) Size Of Rivets 1 4 3 8 1 5 8 3 4 7 8 1 Minimum Spacing Center to Center 1 'i 'i 2 ^i '^8 3 46 STRUCTURAL DRAFTING The maximum spacing allowable is usually sixteen times the thickness of the thinnest plate they go through. The minimum and maximum limits placed above are not to be used wherever possible. Few engineers consider it advisable or permit spacings less than 2| inches and 3 inches, or, more than 4 inches and 5 inches for f-inch and |-inch rivets, respectively. The minimum limits above refer to the center to center of rivets, while the maximum values refer to the distance center to ^—e — e-- -e ^ Gauge line a b Gauge line- Fig. 40. Angles with Gauge Line center measured along the gauge line or line along which the rivets are placed. Gauge lines may be single, Fig. 40a, or double as in Fig. 40b. The gauge of a shape is the distance of the gauge line from a certain base. In the angle it is the back, in the channel it is the back, while in the I-beam it is the bisecting line of the web. The gauges for standard channels and I-beams are given in the handbooks of manufacturers, such as Cambria, Carnegie, etc., which books also give the size of rivet or bolt which can be used in the flange of any certain I-beam or channel. This does not mean that the size of bolt or rivet there given must be used in the web also, in fact, J-inch and |-inch should be used in the web, no matter what size is specified for the flange. The standard gaug,es for angles are given in Table VII. While a double gauge is shown for a 5-inch leg, it is very undesirable to use it. Do not use 5-inch legs with double gauge lines. Likewise, do not use a single-gauge line on an angle with a 6-inch leg or more, unless specially told to do so by those higher in authority. Fig. 41. Section Showing Crimped Angle, Chord Angle, and Web STRUCTURAL DRAFTING 47 TABLE VII Standard Gauges for Angles (All dimensions given in inches) ' ^ 1 t ' 4- •vj 1 1 1 1 1 II ^ 9' g^ 9 L L ' L • Maxi-, Maxi- Maxi- I mum L mum L mum 9 P/i/ef 9 Rivet 9 Rivet or 3o/r or Bolt or Bolt ■ d 4f / 8 3b ^^ 7 8 2 // / 2 7 4 ■7 8 3 // 7 a // / 1 2 6 3P 7 8 2i // 3 4 I? 7 8 3 8 ■5 3 7 8 ^i // 5 8 // 3 4 5 & 4 ^4 7 8 ^4 14 5 8 / 9 16 1 L ,9' 9^ L 9i 9a . 8 J 3 6* ^r 1 -3 £i : 7 2b 3 J 2. li 6 2i ^k *When thickness is \ inch or over. In the spacing of rivets in crimped angles, the distance ''6", Fig. 41, should be IJ inches plus twice the thickness of the chord angles, but never less than 2 inches. The grip of a rivet is the length under heads after the rivet has been driven. The length of a rivet is the length of the shank before the rivet is driven. Fig. 42, re ^^ t these lengths for various grips being easily found in any manufacturer's handbook. Care should be taken in case of castings to add \ inch more to those values given. Rivets may have two full heads or may have one or both heads countersunk or flattened or any combination. Such conditions are signified by certain signs. Fig. 42. Rivet Before and After Driving 48 STRUCTURAL DRAFTING E jC^ Kyi j:^ A ji:^ ^y — ^:7 a ^^ ^ ^y^ i b 1 all of those in common use being listed in the handbooks already referred to, and also shown in Table V. A rivet can be driven as close to a projection as one-half the diameter of the head plus J inch. This requires a special ''dolly". 2 1 The dolly generally used requires -i^ +7 inch. This is about \\ inches for a |-inch rivet and about \\ inches for a |-inch; see Fig. 43 and Table V. In some instances a special gauge, that is, one other than given in Table VII, is used. In such cases care should be taken to see that the distance A, to the fillet, or curve of the angle, is sufficient, otherwise the dolly could not come down evenly and an imperfect head is the result. When rivets are staggered, it is necessary to know how close they may be spaced in order that they may not be less than the minim.um allowed distance center to center. Table VIII gives the distances center to center of rivets for given values of the spacing and gauge line. The dis- tances below and to the right of the upper zigzag line are large enough for f-inch rivets while those below and to the right of the lower zigzag line are large enough for J-inch rivets. For example, if the gauge ''g' was IJ inches, the spacing must be at least 2 inches in order that the distance center to center would not be less than 2f inches, the rivets being | inch. If the rivets were i inch, the spacing must be U inches or more in order to have the distance center to center not less than 2\ inches. These values are found by going down from the value If inches in the top row until a value equal to or just greater than the 2f or 2} inches is found, and then following across to the first column where required spacing is found. > A L c Fig. 43. Diagram for Minimum Rivet Spacing STRUCTURAL DRAFTING 49 TABLE VllI Values Center to Center for Various Spacings (All dimensiong in inches) VALUES or ^ rOR VARYING VALUES 0? g AHD 5 < V ^^ VAIVIS or 3 Inches VALUES OF g Inches nches Inches Inches locf7es Incheslnches Inches Incfieslncttes Inches Inches inches Inches i ^ V < p > 7 S 1 'i ii '1 '^ '1 U^ '1 ^ ^^ ^i 2| 2| 1^ 'i 4 si H si ^/6 ^i ^1 ^^ sH sE i ■'i s^ sF, si 3 ^^ 3.1 2l ^i / a- 10 4 p// 2/i 5 si si si si > < < < > <7(? 3 3 4 4 T ^i ^i H si s,i s!1 s,i si 3 'y p'J "^8 p/^ Vff NOTE- Values belo\/\/ or i (4 H It '■o nc, 7/7/ 1 < f Upper zigzag lines are large enough for ^ ri\/ef^ lower " " " " '.' " § Care should also be taken that the rivets are not so close that there will not be at least I" between the holes in the direction of the line of stress, see Fig. 43d. In many cases a row of rivets must be driven below another row and in material which is perpendicular to the material in which the first row is driven. Such a case is in the cover plate of a plate girder, or for that matter in most cases of cover plates. In such cases it is desirable to know what spacing must be used in order that the dolly will not be interfered with by the rivet already driven in the other row. Table IX gives such information. It is to be noted that the value Y is the distance from the inner side of the leg of the angle, and is not the gauge. For example, let it be required to determine the minimum stagger for f-inch rivets in a 3|-inch leg of a 3i''X3i''Xf'' angle. The distance 7 is then equal to the gauge of a 3-inch leg less the thickness of the angle, or Y=2" -V 8 — 1 5ff -L « 50 STRUCTURAL DRAFTING TABLE IX Minimum Staggers 1 ,11 . r\\ rh r\\ rh ■ i^ , c = Is for 4 rivets -if'-f- — r ) rh rh ^ Vr' ^ ^ ^ ^t \ H^ N^^ -^ \H^ U) \9^ DIAMETER OF RIVETS VALUES OF y 1^ i| >i ',i >l ll 'i 1,1 -1 1 1> li 3 4 '/ 'i /^^ /i /5 rs / ,9 J 4 / J (9 I li 'd 'i //I 'i / 15 16 13 w II / J All dimensions in inches Looking along the top row the value If inches is found and going downward to the |-inch line of values, f inch is found to be the least distance that the rivet under consideration may be driven from the one in the other leg of the angle. In some cases it is possible to drive rivets opposite if the proper row is driven first. Thus, in the 5''X3i''Xf'' angle of Fig. 44, if f-inch rivets in the 5-inch leg were driven first, those in the 3-inch leg must stagger by | inch, as figured above. Fig. 44a, but if the rivets in the 3-inch leg were driven first, the distance Y=Z" —\" y N^ ^ Jl-\ '^T 28 ^\.y a b Fig. 44. Rivet Stagger < s^s J . .2 ca a § c ^ • o c o (A « o. o o J —<» -«\i"M^ •v^j -n -KXj (\j or> rri i>^ ■"XI -^ -"Vj <^ <3 ^ '^r ^ iTi ir\ lO >o 1 1 1 <^ 1 1 1 "C; 10 1 1 1 in QC CQ o UJ 9 q: o Q: b_) 1- UJ z on ■V 05 C>, Cb % 'Vj 'Vj fA •^ '^ "X "<> '^^""V"'Vj'^ ^ -f^ va N K-^ -^ «>j r^ (Vj VO N, CO Os r\j CVj t\j CVj "''Vj-^ioo"'^ "'^ ^ "" <\, -^ '<^ '^ "^ ""1 'SJ. tf> VQ N ►r^ tr^ tr^ rr^ "Hj -1^ "'CO \0 '^ >^ 0\ 'Vi ^J fVi 'V/ ■v,Co' (A VQ >0| tc, rr^ rf>( "='* ^ ■moo iTi \0 N (X5 (\j 'Xi (Xj 'V. "i(Vj"'f^"^i(Xl"'^ (D^ Ci ^ (Xj (\j fO| rv^ fT) "'^»"t>S '^ "vJ- TV VQ ro, -oi ro, roi -lOo'^'OO '^'CO'-'^ -'^ "IQJ ■n VQ N,, Co (Vj (\j CVi (Vj r\j N>1 «N, rr. (Xj -^ > w> «"! '^ '^ "^ rnraO '"'55"'* -^"-^ '^(?j ^ ^'^ <5 i\ r\, 'Xj 'Xi (V. "V^ "'Vj "«X "^ CO o <:> "~ '\, (Xj "^ f^ ""» ""^ N^i (\j "^ 'ig- lA «"! ''^ f^ «^ ^ "^ -"3 'Xj 'Vj t\l •^■00 "^03 ""a "Tj ^ tf> >o "V % % 'Vi fXj CO 0. Vi ^ 'Xj 'Vi '"'V "^ "- (Vj f^ ^ to, N-, s(> l<-\ '.'^ i \ " / -lOO CVj (V, 'Xj (Xj "3- ^ u^ vo (Xj (\, 'Vj i\, '^*0-«i03"'\,-.fVj "V 03i O Ci (\j 'Xj (Xj -""I IK*) "'^ "•<» ""0 -- (Xj f^ ^ M", to, N>, rr. '^ 1 =s "^ Vi; '^ ^ 1 - ^ 1 CVJ -- f\i "Xi cVi -"Vj'^iOo'^ICO"'^, »<> 'a- ""1 vo (V. (Xi (V, Oj -',,"'05 ■v CO c> c> (Vj (Xj (Xj '^ ^ -. CX, to, to, tr^ Mj^ to. 1^ J 1 1 r i^iOD ■^153 -1,^ -.to -oa -- fX, cXi (\j -^ ^ ^ "O rv, (\i fXi f\j ■^|'>'^'Ii-^'=o "«Vj >, Ci -- -- -- (\j (Vj (Xj if^ ^ >A fXi (\i (\j (\i VO IV CQ <>i fXi f\j i\j 'Xj <:i ^ -- CVj to, to, to, to, iTiHD CO Oi C) ~^ "'* -^"O i\j -o r* > fVj-CV^ C\j 'Vj VO "V DO (Xj (Xj (Xj (Xj (Vj to, to, to. 'Vj f^loo N, CQ Oi Ci - - ^ rv, -V (Xj -^ ^J' (Xj fVj (Xj fVj 'S,*lN<,0'^^»'^ \q. «^ \0 Nv (Xj (Xj (Vj (Vj '^'«6"«V,"'n.-Moc OO On Qi ■-. (\, CXj "^ "^ — i\j- -"» ^'^s "'05 > «> VO ■X CO 00 o^ 'Xj (Xj (V, (V. ^ in vcf n7 (Vj C\j fX) (Vj eg" On '5> ^ (\j (X, "^ >«> > 1^ \ -lOO "^ ^ u> vO -V CO o "> "K«5 "'1^ _„ ci --r 'Vj -^ '\j % 'Xj >\i ^l ^ T\ ^5 (Vj CVj (Vj f\j "> "!<<> N 00 C^ Ci CVj CVi (\j ""1 '*> / r^ s^ % i-MOO fX, C\j -^ •^ >A vo -v Qo "^"■^J ~'0O^"^ On Ci -V (Vg ■"• "Xj % rvj '^'HJ'"'<0 '^ ^ ^ 'f^ (Vj CVj CVj (\, ''"»'^HO'^"'V VO -V (O On fVj ::; |\o "^ '^ IQ VQ "V ^ ?? ^ ^ cv, cv: (V^ cv, cx, cv, % "Vj^j ■^ c/ 1/5 =1 -ITJ -ltVjrr\K!J "Xj (Vj C\j (\j (^ <^ fn <^ -fq- -KV) mh;j 't "^ •<» -^ -^t-KVjir*^ iT) in u"^ lO (D STRUCTURAL DRAFTING 59 American Bridge Company practice requires the smallest pin to be not less than three-fourths the width of the eye bar. Bars of a square or circular section could, as in the case of bolts, have a screw thread cut on their ends and by means of nuts be connected to the other part of the structure, but such an opera- tion would be costly since the bars are long and much of the section would be wasted for a great length. In such cases the bars are ordered 6 inches longer than required and this 6 inches is, after heating to a welding heat, upset or pushed in 6 inches, thus increasing the diameter of the bar at the end so that the diameter at the bottom of the screw threads \\ill be greater than the diameter of the original bar. This is done so that the bar will break in the body, and not at the joint. The sizes of upsets for bars of various sizes are given in the handbooks. Let it be required to determine the size hole through which a l|-inch bar w^th upset end would pass and the nut required. We find opposite the IJ the value IJ, sho^\ing that the upset will be 1| inches. In another table opposite IJ is given the size and weight of a square nut, viz, IJ inches thick, 3 inches on the side, and weight 3.175 pounds. The use of square nuts is not to be encouraged, the hexagonal form being the better, on account of their lighter weight. Instead of the rods being fitted with nuts and threads at their ends, they may, as mentioned above, be made into loop bars. Loop bars are welded, and for this reason are not to be desired since welds are never as strong as the original. However, the loop bar has 100 per cent excess through the pin, and in order to have an efficiency of 100 per cent it must have a, weld with an efficiency of 50 per cent. Since such a weld is well within the limits of possibility, it is per- missible to use loop bars in highway bridges or other structures where the impact is not great, and in counters, since here the pins are usually of such a diameter that they would be too great for an eye bar of the section of the counter. Table XIII gives information regarding loop bars. They must be made of WTOught iron since steel does not weld well. Clearances. It is very important that each member of a struc- ture fit together well in the field; and it is equally important that the draftsman should so detail his work that the various parts of any particular member should, without further cutting than the 60 STRUCTURAL DRAFTING first, fit together. Also the rivets should be so spaced and placed that they can be driven. The rivet clearances have been mentioned under ''Rivets and Rivet Spacing" and will not be taken up here. It is sufficient to say that on the rivet clearances is where the novice makes the most of his mistakes. Where the distance between the outer faces of several mem- bers placed together is to be com- puted, it is necessary, on account of the liability of plates to exceed their nominal thicknesses, and rivet heads their nominal height, to make certain allowances. The usual practice is: (1) Between eye (or loop) bars allow Y6 inch. (2) Between an eye( or loop) bar and a built-up member | inch. (3) Between two built-up members z inch. Fig. 47. Joint Showing Clearance between Members For example, suppose it was required to compute the distance out to out of the members shown in Fig. 47. The clearance would be as indicated, and the distance D would be: D= -H 10 + 0.4+f + i+0.28+i + li + h^'i) = 18.485= 18i inches This value would be the gHp of the pin which was used at this joint. The 0.4 inch and 0.28 inch in the above are the thicknesses of the channel webs, and the f inch is the height of a | inch rivet head. In the use of eye bars, it is essential to see that their heads as well as their bodies clear. In order to determine the dimension of a section for the necessary clearance, the size of the head must be ascertained. This is best done by drawing up the head to a large scale. The method of procedure is as follows: (1) Draw the circle representing the pinhole; (2) for the width of eye bar under con- STRUCTURAL DRAFTING 61 sideration, subtract the radius of the largest pinhole in Cambria for that bar from the radius of the given head and add the result to one-half the pinhole diameter in your particular case, thus giving you R, Fig. 46; (3) with the radius R describe a full circle; (4) with -j^i^, Fig. 48. Eye-Bar and Built-Up Member Showing Clearance Allowed the center of the pin as a center and a radius equal to 2 J R describe a couple of arcs 1, 1; (5) parallel to the bar and at a distance 1^ R from it, draw two lines, 2, 2, intersecting the arcs 1, 1; and (6) with these intersections as centers and a radius equal to H R describe the small arcs completing the head, see Fig. 46. No material should be closer to the edge of the eye-bar head than I inch. This clearance should always be given, see Fig. 48, a b _ci d_ _0 Ci_ o ^ o ^ o "^ d^ r r-^ or more IL vIT Cr" 9 Fig. 49. Riveted Joints Showing Clearance Allowed although the clearance of | or j^ on the side should be allowed as usual in case it was against a built-up member or another eye bar. 62 STRUCTURAL DRAFTING P In case the head is on the interior of a channel or so as to come near the fillet of an angle, the J inch must be measured from the curve of the fillet. This J inch does not apply to the body of the bar, the clearance there being J inch in accordance with what follows. Wherever several pieces of metal are riveted to the same side of a plate or other member and could, theoretically, come close against each other, J-inch clearance is allowed for each case where the ends are not planed. This allows for the slight variations in length liable to occur when the surfaces are sheared. The members will then be sufficiently close together for all practical purposes. In order that no errors occur, the joint should be drawn up on a separate sheet to a scale of at least 1 J or 2 inches to the foot in case the pieces meet at an angle. In case the pieces meet at right angles, the distances may be computed. Fig. 49 gives a few of the most common cases. As in the case of Fig. 49c and 49d the clear- ances at one end will be J inch and at the other end may be more, and should be, in order that the distances h and h shall be the same. (The distance from the first rivet to the end of the angle is usually Ij or IJ, generally the latter.) It must not be understood that the clearance is exactly J inch; it must be at least J inch, and may be more, up to | inch or | inch in order that the distance from the rivet to some other Fig. 50. Column and Beam . . . . Connection Showing Clearance pomt Or riVCt may bc m au CVCU ^ Uich Or J inch. When I-beams or channels are placed as mentioned above, |-inch clearance or more instead of the |-inch is required, one of the most common cases where such clearance is required being shown in Fig. 50. For other clearances in beams see *'The Detailing of Beams," page 72. Wherever bolts, rods, upsets, or rolled bars pass through a hole or slot, the aperture should be | inch greater in diameter or J inch greater in dimensions in case there is a slot. The above is in case the material is rolled steel or iron. In case of a casting, J inch should be added to the dimensions of the member which is to pass through the opening. )o ) o )o ) o )0 .STRUCTURAL DRAFTING 63 ^pjoi/^p jofjii-of: 7^-.^ •^ir^ JO V. > 'vo'§ ^ 0) 00 O ^ ^ " " ■^i*? I? ? '^ PC' \ R f 1 ./^v , — ./n. \, .Z^. ./^. s \ / \'^ \ i V V- M ) V V V \f ) Single Lacing (r =^j =30°) Double Lac/ng [r = §-Q, -45°) r C r C 1" 4 O'-IO" 1 " 4 1-3" 5" 16 /'-of 5" 16 ill 3" 8 l'-3" 3" 8 I'-IOf 7" 16 r" 16 1 II 1" I'-d" 1" a 2-6" 9" /6 I'-iof 9" 16 2-9i" 5" 8 ^-'-1" 3" 8 3'-,f follow. In general, the combinations consist of plates or other shapes held together by angles, lacing bars, or tie plates, the size and section of the angles being determined in the design since they are part of the section of the member itself, while the lattice bars and tie or batten plates are chosen in accordance with the specifica- tions employed. The specifications for lacing bars make their size a function of the distance between rivets. Table XIV gives the thickness of lacing bars for any distance between rivets. Detailing of Beams. This is for the most part done on "Beam Sheets". These sheets are the size of the shop bills, 8JX14 inches, and have a printed heading and footing as on the shop bills. Between the heading and the footing are printed elevations and cross-sections of I-beams, as in Fig. 57, the number on a sheet varying with the number of dimension lines above and material below, i. e., from two to four. In some cases, those blank sketches are printed lengthwise of the sheet and then two only are placed upon a sheet. In case a channel is to be indicated, the draftsman blocks out one half of the section or end view, see Fig, 58, lower cut. STRUCTURAL DRAFTING 73 On these blank sketches the draftsman notes the rivets and rivet holes, puts on the connection and other angles, and shows all other information necessary for the complete fabrication of the beam ready for the structure of which it is a part. Figs. 58, 59, 60, and 61 are beam sheets which have been filled in, and illustrate very nicely the general principles. The general rules regarding beam sketches are given in the following : In all possible cases the lioles in the end connections to the webs should be according to the standards given in the haridbooks. If the Fig. 57. ^Method of Detailing an I-Beam on Beam Sheets connection is standard for that beam, no mention need be made of the fact, and if it is in the center of the iveb, no dimension is required, see Fig. 58, first view, left end. If the connection is not in the middle of the iceb, but it is standard, the location of its center from the bottom shoidd be given, see Fig. 68, first vieiv, right end. If the connection is not standard, it must be noted and detailed as in Fig. 59, second view, and if it were not in the center of the web, its distance from the bottom should be given as in the case of the standard connection. In case there are holes in the outstanding leg, they should be shown as in Fig. 62. Where the leg against the web is standard and the outstanding leg is of the same punching, no dimensions need be shouii, but the outstanding leg must be shoum and the material notation of the angle put on as in Fig. 59, first view, right end. Saline Bridge Company Order Mo_^_^^_^- Sheet r4o__ A _5.B.Co.Conrr_^l805 ADOmooR_^^-^RmzYA 16 -I' Cope to I 5'x 50^1 O 16 Ki ^ J -10? ^r-5A JV#" ■9-^ ki eW^ ,. 4-3 f ^^ 5'-5§ IO'-4i" 5F 5i' ^ MAK ^.4z'X'^ ^ifLx. fPl-Jl _ _ MARK .^^l^/_ f-l^_ _ , Copeho/rfo^O'k dO^^I 16' -i Copeto/5x4^*I (a5 shown) i 5^3 % ■5 j/d 6 -df 5^or V //-J/l i ^ 'm:^ 5-~3r f m I6'-Zfi" ' — ^ MAKE Qne-J^:'^3i5'iIxJ6t9§'i MARK- J_''f z^/--^^--?. 9'-6f r^w r^/ /i //. *-^^4 "cut not chipped Length of I = 9'- 5 i"- 2-l2"5pec /-Oi" 3(a) / '-3 =6-3" r-2~ 16 holes - -^ \^ ^'- 3"x3 "xffX^9'~5J' t^TT ife-t ^ j:i -J v:\3" 8" \6f' I l4(3>6"-r'-0" - - ■-■ L-^_- MAKE ^^C I8y3l3y_x9i6_f__ MARK r?^!^^ -"^f — ♦ . ^ I — 4? ^ MAKE Oneld:k40^[_xJ4z6:^^ __»_ w >i V l^_'4l"_ -^r^ ~5W 4e ^♦* HNRy^4:''_FJ.f50_ a!"" Fl*'32 4^^FI. ^43 14-6" I5''4p r 5/ \Ame ^y0iK/:^..\9l/ Checked byJ^'^j^iq// ^^FOJKUfi BlP'0_ Chicago _ _ mCHARGF r.^ ^^^"^^ 4^^ Floor Beams 5E OFJ Fig. 59. Typical Beam Sheet Sliowing Dimensions Filled in According to Specifications Order X\oJJ19J__ 3.B.Co.Cortr.^l806 Saline Bridge Company Sheet no„.^^. SHirrLER BRANCH -^ (I 17-0' ■^ pp-x 'fr\ IM^CC 10" !i" I'-O" 5-0" 3^r 5-0" r-0' ?t. 6-0" (o ll-O" 16-0" l6'-8^' cc. holes H^ F^- r V^^H" One Girder Mork_ ^Z''fL 16__ _ ?.-L5'j<5~0 '^L^V'-O" _ JzCL5_e_p_5._ ^'jpxO'-oyg.^ _ ^-/L BoJt3_ xjy-'d'lg^ 16-5' ^ I'-O" 4'-9" 4'- 9" 4'-9" I'-O" 5'- 9" h 10'- 6" is'-y Q^-^- QlrP^r_ Mqrk_^^'^_^■*9 _ 4-_CJ.5epj.^l5x0l6;igS5hipJoq5e_ _ ^-i'Bqlt5xO}8"Jg. J Made. ?>y.^.B..^5.\9II HOLES I PJgm-_ _ .. -^---'-'^-- -----^ CHECKED BY ^r>|,.9// P/\/Nr_ Q^A ^oqt_ qf_ _PA^2ENGER_ 5TA ._Plttsburgh_ im charge of_ PQe.__ . graphite E"*^ Floor Beams Fig. GO. Typical Beam Sheet Showing Dimensions Filled in According to Specificatious Saline Bridge Company ^ , , .^ Order Mo.iC/Ay-_ SheetNo._/?_ 3_,BXaConrr.fJ83l ARP0KLYN_ BRArscH R\\/^-xsji"_Pj_qm _ Made BY_/f // _/^ifi 9^/ /J-' . ~, Fir^t Floor Beams ^ lyrS/ it V\o\jE.5llJl'^JP2-MPIf^^ Checked by/l4^9// marked other w/se _ CUSTOM _HOy3_E^_Ne_w_Yo_rJ< In Charge OF_-^€/zrZ?_. Fig. 61. Typical Beam Sheet Showing Dimensions Filled in According to Specificationa 78 STRUCTURAL DRAFTING Whe72 beams arc on a slight bevel, it is desirable to have the bevel taken up in the connection angles and the holes in the web of the beam ^i si" ^j ) 0: A' /fVJ5*/ ^^ • '"^1 1 1 4 1 h -f\ > > % 4 ►- 1 i h t 1 r i 1 \ i \ . ^ 0' —f ' il v V. -' *^ n Fig. 62. Detailing Connection P ate When There Are Holes in the Outstanding Leg at right angles to the center line. The bevel should be indicated, see third vieiv, Fig. 58, right end. In case field connections to the web are made, as in cases where other beams are riveted to it, it is unnecessary to give the vertical spacing of the holes if the connection is standard. The horizontal distances and their number ivill designate which connection is required. For example, in the first view, Fig. 58, the six holes 5|-inch centers show this to be a standard for 12-inch beams, while the four holes 5^-inch centers indicate the standard connection for a 7-inch, 8-inch, 9-inch, or 10-inch beam. In all cases the vertical spacing will be 2| inches. It should be noted that in all cases of standard connections of 8 holes or less in a vertical row the rivet spacing is 2| inches, while all over 8 have a spacing of 3 inches. ^j Jorsty "^ ^ £> B< Joist z >^l>-£> >^-o -^1 ^ J Girder Fig. 63. Method of Bringing Beams to the Same Level on Main Girders The centers of all groups of field holes above the bottom of the beam should be given. STRUCTURAL DRAFTING 79 Tie rods are put in in case no beams are riveted to the webs, to keep the beams from lateral motion. The holes for these are 4J inches apart, and they are referenced as in Fig. 59, second view. Where tivo beams are placed close together, they should be connected by "sep- arators'^ to prevent lateral motion. When such is the case the holes are indicated as shown in Fig. 60. The various kinds of wall anchors are shoicn in the handbooks and in Fig. 20. Care should ^ Fig. 64. jNIethod of (doping a Beam Top and Bottom be taken to provide for their connection to the beams when required. When beams are used in building work, it is usually required that either the upper or the lower flanges of part or all of the beams be at the same elevation. When the girder or main beams are deep enough, the Cope to 15" X 42** I lf^ c^ ^ if^ a ^ _,j <^ fVj Co'pe to 9"x2I^I C Cope to 1 2" X 31.5^1 5''above top I Cope to 15" X 3 5"^ I b Cope to 9" X 21 **I O) O iVj -JivW. le" h .5si ^ ^J e f Fig. 65. Methods of Coping Beams to Fit Beams of Various Heights ^oist top or bottom flanges may be brought to the same elevation as shown in Fig. 63 which shoivs a 12-inch and a 7-inch beam. The connection 80 STRUCTURAL DRAFTING angles are in all cases arranged so that the rivets through the girder iceb and the smaller connection angles go through the connection of the larger beam also. In case it is desirable to have beams so as to have all their tops or bottoms at the same elevation, it may be accomplished by an ^- NOTE:- That cur at point A extends to b intersection of for side of wet? wit In line of bevel. Fig. 66. Method of Cutting Flanges When a Beam is Coped on a Bevel operation known as "coping" the beam. By coping is meant that the flange is cut back for a certain distance depending on the size of the beam which is to join the beam under consideration and the web is then cut down a distance X and sloped back on a bevel of 3 inches in 12 inches, see Fig. 64. Fig. 64 show^s a beam, coped top and bottom to fit into another beam of its own depth. A beam may be coped on top only. Fig. 65a, or on bottom only. Fig. 65b. Other conditions of coping are shown in Fig. 65c — f, together with the ways of indicating them. Fig. 58 shows some indicated in the beam sketches. When a beam is to be coped on a bevel, the flanges are not cut to a bevel, but are cut as in Fig. 66. The distances a and b should be given alloicing a ^-inch clearance, and the portion of the beam coped is to be shoicn cross-hatched. This method of cutting to a bevel shoidd be u^ed whenever possible, ivhether the beam is coped to fit another or is simply cut to a bevel. When a single beam or a girder formed of two beams having a cover plate riveted thereto is cut to a bevel, the cover plate shoidd be sheared- to the line of bevel and the beam should be cut as shown in Fig. 66. Fig. 67. Method of Cutting an I-Beam or Channel to a Bevel STRUCTURAL DRAFTING 81 When an \-heam of a channel is cut to a bevel across the depth, the cut should be made as shown in Fig. 67, and the distance *'a" should be given. Detailing of Roof Trusses. The first thing to determine in this respect is the outline of the outer fine of the roof and the end, and the center depths. The chords should now be located by center lines corresponding to the gauge lines of the angles, or the center of gravity lines of the pieces, as the case may be. The above mentioned deter- minations may be obtained from the architect's drawing and from the stress sheet; and in many, if not most all cases, the center lines of the chords are shown on the stress sheet. The stress sheet may be an outline \dt\i the stresses and the sections on it, or it may and in fact should be as shoTSTi on Plate I. Here the designer, who is an experienced man, has shown the general details. It now remains for the draftsman to draw this up so that the shopmen can make it. After he has finished, the results will be as shoTMi on Plates II and III, which vr\W now be discussed in detail. After the center lines of the chords are drawn in, the angles themselves should be dra^^n on by laying of the gauge lines on one side and then the other' edge of the leg on the other side of the gauge line. After this the top chord should be divided into a certain num- ber of equal parts at each of which a purlin is to be placed. This done, lines from these points should be dra^Ti perpendicular to the top chord and their points of intersection with the bottom chord should be noted. From the intersection of the center one with the bottom chord to the apex or top, a line is now drawn, and this is the center line of the main interior tie, ,or tension member. The member itself should now be draT\'n on this gauge line. After this the other members should be dra^sTi in as showTi. In order to proceed, the distances between the various points of intersection must be carefully computed, thus giving the remain- ing data necessary to compute the bevels, which should now be done. In order to determine the length of the members and the sizes of the plates, it is now necessary to take each point of intersection where any members meet at any other than a right angle and make a layout of that joint to some large scale, say 1| to 2 inches to the foot. The customary ^-inch clearance should be allowed where there is any liability of pieces touching and, after the ends of the 82 STRUCTURAL DRAFTING a. hH CL, 1 ■I'i 1\ ..0->9 .^'.U'S -II bupojg pjoH3 J9MO-1 6upojg P-iol|Q jaddQ sui|jnj (OS|i043Q J 1 . . ■•«' in :p« *^ Ul VlLUQ -■ AjUO Sd "1' ' rjui,.UiO-- T 1) '-'"■■^ '.r jB-si .T" SI STRUCTURAL DRAFTING 85 various angles are drawn in, the first rivet is set back 1|, IJ, or IJ inches as the sizes of the angle and of the rivet allow, and the other spacing is so arranged as to make the size and shape of the plate advantageous and economical. The distance from the first rivet to the intersection is measured off and noted. After the layout for each joint has been made and the necessary dimensions of the plates and the distance from each intersection to the first rivet has been determined, the length of each member may be computed. This is equal to the length, intersection to intersection, plus the sum of the distances from the first rivet at the ends to the end of the member, minus the sum of the distances from the first rivet to the nearest intersection. For example, in the main interior tie IIa L2, Plate I, the length, intersection to intersection, is 21 '-10 J'', the distance from each first rivet to the end of the angle is IJ inches, and the sum of the distances from each first rivet to the nearest intersection is (4J+9) = 13J inches, which is V-\^" . The length of the member is: 2r-ior+2 {i\")-v-nj'=2V-Q" At the point L2, Plate I, a field connection must be made as well as at L 4 on account of the fact that the truss must be shipped in part in case the span is larger than 30 feet, the length of an ordinary gondola freight car. At Z2 both legs of the angle should be connected, the horizontal leg connection being by a plate. In case of riveted lateral bracing such as is used here, the connection plate may also be used as a splice plate, see Pis. 8, 9, and 10 in Plate III. At point TJ^ as many shop rivets are put in as there are field rivets required. This will keep the plate symmetrical, and will allow the same templets to be used for the top chord and main interior tie on both sides of the truss. This more than overbalances the cost of driving the few additional shop rivets. At Zo in this case the truss has been designed so that the rivets are symmetrical about the point of intersection and, therefore, only a sufficient number are required to take up the direct stress in the top and bottom chords. In many cases the end of a roof truss is as showTi in Fig. 68, in which case the number of rivets io L2 may be calculated from the equation: QiRe n^v — Rn = V 86 STRUCTURAL DRAFTING in which ?? = number of rivets required; ?;— allowable stress on one rivet; R=the vertical reaction; 2>'=the rivet spacing in inches; and e= distance shown in Fig. 68. The number of rivets in Lo Ui may be determined from the equation : nh—Sii QSei V in which *S is the stress in Zo Ui, and ei the distance shown in Fig. 68. These formulas allow for the stress due to eccentricity. The rivet spacing y is usually taken as 3 inches, although it may be taken as any value permissible by the specifications. In the detailing of the lateral systems/Plate III, the same method of procedure as above mentioned should be followed. Care should Clip- Angle Fig. 68. Typical Detail for the End of a Roof Truss Fig. 69. Method of Riveting Clip Angles for Carrying Purlins be exercised in making the layouts for the lateral plates so that sufficient clearances are allowed, both in regards to clearances between members and clearances in rivet driving. The purlins, or rafters, may be detailed directly upon the main sheet with the bracing or truss, or upon a beam sheet, preferably the latter. In Plate III they are upon the lateral sheet. These purlins should be riveted, not bolted to the chords of the trusses. In order to facilitate erection, clip angles should be riveted to the top chord as shown in Fig. 69 so that the purlin may be put in place and riveted up without having to hold it in place with ropes or chains. STRUCTURAL DRAFTING 87 Also by this method the purUn may be put in place and used as sup- port for erection apparatus. In Plate III, the additional pair of holes at panel points of the top chord are for these clip angles. After the draftsman has finished his drawing he should care- fully check up all dimensions and bevels and inspect the drawing for errors in rivet clearances. The passing in of accurate detail drawings will soon result in a promotion to checker, a more pleasant position, but one with greater responsibilities attached. Detailing of Plate Girder Spans. The information which the draftsman has to start with is in the form of the stress sheet. This may be as Plate V which is the latest and most approved form, or it will be like Plate VI. In both cases the number of rivets for the lateral connections are given, but on Plate V the rivet curve for the spacing in the flanges is given and also the curve of the total and dead load shears and moments. As soon as a plate-girder stress sheet is turned over to the draftsman, he should lay it out at once and determine the exact location of the web splices, the stiffeners, and the cover plates and their lengths (if not given), should decide upon the lengths of the panels of the lateral bracing, and should also make layouts of the lateral plates, if possible, so that the material can be ordered at once if necessary. In making the above layout the following should be observed : (1) Be careful in locating splices to see that they come at a panel point of the lateral system. (2) Locate all splices and stiffeners with a view of keeping the rivet spacing as regular as possible. (3) Have the panels of the lateral systems equal if possible. If not, have a smaller one at the ends of the girder, the remainder being of equal length. (4) Stiffeners to which cross-frames are attached should have fillers. (5) The outstanding leg of stiff ener angles should have a gauge of 2| inches or more. This will enable the cross-frames or floor beams to be swung in during erection without spreading the girders. (6) It is always best to use as few sizes as possible for stifTeners, connection plates, etc., and avoid all unnecessary cutting of plates and angles. (7) Locate the end holes for laterals and diagonals so that they can be sheared by a single operation, see Fig. 70. This will, as a rule, throw the end rivet further back from the working point, and may increase the size of the con- nection plate, but it is desirable. (8) It is preferable to have an even number of panels in the lateral system since the girders can in most cases then be made symmetrical or nearly so about the center. t\i -~ ~, ^ ,oooooi^-.i ^p^g- ,0000£--,./ ^P^£ CO Wo ^ ^ fo ^l a (A m O Cl, oo 'JQ S Or (T) t3 ~-J <:^ (ri "*- ^ -^ c^.-^^o, -t-~ ., -^ .H .^. "?i .. 0^ VC s ^ .1 ^ « %.-. co^ ,.9 -.9 ..9.9 ^oog,9 k5 ''a — I CO «l Ci •^ ^<:i <^ \ QQ ^ ^ ^ "^ ^ ^ c^ ^ ^o ■^ <• ^ Ci tSr ^ K c^ '^ t; ^1 Co to 0^ ^ ^Q^ ^ 00009 e^ 00009 -e £ 0OS2C 00G2i^ OOGZi , 0093^ v00005 00009' 00009 00009 00929 00929 00929 00929 00929 -G- 00009 ■e 00009 00009 00009 ^ m 00092 ^ 90 STRUCTURAL DRAFTING (9) The rivet spacing curve should be constructed if it is not given on the stress sheet. In addition to the above the following rules which apply directly to the detailing should be followed. They are: (1) The second pair of stitTeners over the ends of the bed phxte shall be so placed that the plate will extend not less than 1 inch beyond the outstanding leg. (2) If spans are on a grade, unless otherwise specified, put the bevel in the bed plate or masonry plate and not in the base or sole plate, sometimes called the bearing plate. (3) In short spans, 50 feet or less, put slotted holes for anchor bolts in both ends of the girder. This will usually be covered by a clause in the specifi- cations. (4) In square spans show only one-half, but give main dimensions such as "overall" and ''center to center" and lengths of cover plates for the entire span. one operation Incorrect, two operations Fig. 70. Method of Locating End Hole.s for Laterals and Diagonals so that Thej- May be Sheared by a Single Operation (5) The girder detailed is always the far girder and is looked at from the inside. * (6) If a span has no lower lateral bracing, only sufficient of the ends of the girder are to be shown in order that the detail of the base plate and its con- nection to the flange may be shown. (7) If the fillers become 12 to 15 inches wide, they become too heavy to be slipped in in the field and they should be riveted in place in the shop with at least two countersunk rivets, (8) When the ends of two girders meet on the same pier the masonry plate should be made continuous, that is, one plate to extend under both spans. Never make the base plates continuous since they could not be riveted up in the field. (9) Detail the bed (masonry) plate separately, never show it in connection with the base plate. STRUCTURAL DRAFTING 91 At least two sheets are necessary to complete the detail draw- ings of any girder span, viz, (1) the Floor, Masonry, and Erection Plan, Plate VII, and (2) the Girders and Bracing, Plate VIII, although in many cases the information on this sheet is put on two sheets, the girder on one and the bracing on the other. The first sheet should show: (1) A cross-section of the floor. (2) A longitudinal view of the floor. (3) A side elevation of the floor. (4) The angle of skew and the width of the bridge seat. (5) The elevation of the bridge seats and the grade of base of rail. (6) The marking" diagram. (7) All clearances. (8) Other essential information. In the marking diagram all members which are entirely alike should be given the same mark. It may be, and usually is a fact, that all marks can not be put on the marking diagram until the detail drawing is done since then and only then is it possible, especially with the plates, to determine all members which are alike. Only those members which are shipped loose are given a mark. Thus it is seen that while each connection plate has a mark, only the entire cross-frames are given one mark since the members which compose them are all shop-riveted together. ^^Other essential information" is seldom required. In this special case there is shown another track which it is proposed will be put in in the future. Another case is where each end of the span has a different height from the base of rail to the masonry. In such cases this should be shown. On this sheet should be shown the masonry plates, and if the ends are supported on cast-steel bases the height of these and also the dimensions of the base should be given. The following general rules apply to the second sheet, Plate VIII. (1) At the top of the sheet show a top view of the span with cross-frames, laterals, and their connections complete, the girders being placed at their proper distances apart. (2) Below this show the elevation of the far girder from the inside, with all field holes in the flanges and stiffeners indicated and blackened in. (3) If the span has lower lateral bracing, show below the elevation a horizontal section of the span just above the tops of the lower flange angles. On this drawing show the lower lateral bracing. (4) Cross-frames shall, whenever possible, be detailed on the right hand of the sheet in line with the elevation. The frame shall be of such a depth as /- 5o/e P/. ^4 • M "/.V i c/b Fixec/ fna -/f% I Girders are 2'ymmetrical about c.llne except as shown 73-/0 bacM to baclt of a/jQles 36 '-// " . 36 //" 5' ?i' 6 -9i /•• . - -Yj- . , •■ ..' '., Material Soft 0. H. Stee l Rivets /a diam Open tioles^e^ cfiam. except as noted Leh/qh^''oLahe Erie RR.L.\/R.R . Bridge LL444B. over WitiCHE5TER Av We5T j£ti£CA Brie Co. A Y One 5. TDeck PI 6 it? JpanZ3'/o 'o to -^calez'/Rf. STRUCTURAL DRAFTING 97 to permit it being swung into place without interfering with the heads of the flange-rivets in the girders. (5) Always use a plate, not a washer, at the intersection of the diagonals of cross-frame. The various parts of Sheet 2, Plate VIII, will now be taken up in detail and described *and commented upon. The Webs. As a usual thing webs are never specified in frac- tions of an inch. If so, the next inch in wddth must be ordered and then after the flange angles are riveted on, the projecting portion is cut off — an expensive operation. Webs are ordered in even inch widths and the distance back to back of angles is made J inch or I inch greater than the width of the web plate. This is sufficient to prevent any irregularities in rolling from projecting above the flange angles. Some engineers favor the web planed down from the greater width and claim that the bearing of the web on the sole or base plate thus obtained is a great advantage. The advantage is slight, however, and unless specially instructed to detail it that way, it should not be done. The web splices should, as before men- tioned, be at a panel point of the lateral system. In some cases the web plates butt up against each other, being planed to an even bear- ing. In most cases, however, the ends of the webs are sheared off and the customary J-inch clearance is allowed. In this case the sum of the lengths of the webs as given is 2 (25'-f'0+23'-5f''=75'-9i", while the '^overall" distance is 73'-10'' or f inch less, which is taken up by the distance between webs at the splice and by the small amount, | inch, which web is below the backs of the angles at the ends. This shows the webs to be J inch apart at the splices. It is unnecessary to place any dimensions or notes on the drawing calling attention to this fact since the shop will make this allowance unless instructed otherwise. In case the webs are to be close together, a note must be placed on the drawing at the splice, reading "Webs planed to even bearing." Web Splices. Web splices may be of two forms, viz, that as indicated on Plate VIII which takes shear only, and the moment web splice. The proper manner to detail a moment web splice is as shown in Fig. 71. In the simple shear splice both the splice stiffeners and the splice plates may and should have the same spacing as the intermediate stiffeners, and the rivet lines should be spaced so as to 98 STRUCTURAL DRAFTING correspond to the spacing in the flange angles. In the moment splice this should be done if possible, but this is seldom the case. However, in case of more than one splice occurring in half of the girder, they should all be made alike, being figured for the one with the greater stress. Since a splice plate is a species of filler, it should be given a mark so that in case of other splices occurring the mark and not all the dimensions should be placed upon it. Stiffeners. All stiffeners except the second from the end should have the outstanding leg on the side of the gauge line away from the center of the girder. As a rule, the end stiffeners should have enough rivets to take up the end shear, and the intermediate stiffeners should ^—4 -T^ 0- ^ ^ ^ -^ — ^— — ^ — e -^ — — — ^ ^ — — $ — — ^ -^ <> <} ^ 9 1^ cp -0 — — $ — Fig. 71 Method of Detailing a Moment Web Splice have sufficient to take up the shear at that point. This would, if carried out, require a different number of rivets in each stiffener. Common practice requires that the spacing in all stiffeners should be the same and that this spacing should be the same as in the end stiffeners. In some cases, such as, in heavy girders, it is not possible to do this on account of the large number required in the end stiffeners, and the rivet spacing is then made the same in all the intermediate stifTeners. The rivet spacing should not exceed 4f or 5 inches at the most and should be so placed that it should be symmetrical about the center. When the web plates are of even inch width, the J inch STRUCTURAL DRAFTING 99 2i I" ^^. ^ ^* . II rf N -J V e 5 ^ e -e — Q- e — 0- -^ may be put into one odd space at the center in order to avoid \ inch in the spacing. It may be necessary to put in a few more rivets than are computed as necessary, but the advantage gained by thus making the punching of the plate on the multiple punch possible, makes this advisable. Fig. 72 shows this method of detailing. In order to make the shear plate at the web splice efficient to some degree in withstanding the moment — for although it is not computed to take moment yet it does in reality — the rivets near the flange are placed close together for a few spaces. If the space changes after that, it should increase towards the middle of the web, except in such a case as Fig. 72 where the center space may or may not be as great as those on either side of it. In double-gauge flange angles the rivet in the stiffener should be in the inner guage line of the Sj. flange angle as shown, and no '^ rivet should come closer than \\ inches to the end of a filler. Each like stiffener should be given a mark and in case others of the same kind both in size and punching occur, the mark may be used instead of the material notation and dimension. Those crimped will be given different mark even if size and punching are the same. It should be noted that some of the stiffener angles differ only from the fact that they have holes in their outer leg to which the cross-frames are con- nected, hence a different mark. The length of stiffeners listed on the dra^vang is the distance inside of flange angle legs. Without further instructions they will be ground by the shopmen so as to have a snug fit. ^— ^ -^ ^^ Fig. 72. Method of Detailing Web Plate Stiffeners 100 STRUCTURAL DRAFTING Fillers. Fillers are placed under angles that are crimped sihce the angles are only crimped | inch and not the entire j inch which is the thickness of the flange angles. The fillers are given marks for the same reasons and in accordance with the same rules that apply to stiff eners. Flange Angles. In case of double gauge on the 6-inch flange angle it is better to put the 2J-inch gauge on the inside, no matter ^ QO-OQ^QCDQCDO — (D y^ \ 6\ d) 0- O - ''^^.^ Center line of Girder Fig. 73. Method of Detailing Rivet Spacing with Flange Angles what the thickness may be, since by this operation the rivets in the horizontal flange, providing that is a double-gauge line, may be more advantageously spaced on account of the fact that the required stagger will be less. The rivet spacing in the vertical leg of the flange angles should increase from the end towards the center and should remain the same, as far as possible, between any two stiffeners, any changes necessary being made near the stiffeners. Since a rivet must always STRUCTURAL DRAFTING 101 be in the inner gauge line at a stiffener, an even number of spaces must be between any two stiffener gauge lines, since the rivets must stagger. This brings one rivet in the center of the girder, which can not occur in case there is a splice at the center of the girder. The stagger may then be broken as in Fig. 73, the stiffener angle being placed as shown and the rivet spacing being symmetrical on each side of the center of the girder. Between the stiffeners at the end, the spacing should be the same as it is between the next two stiffeners. The spacing at any point should never exceed the computed spacing unless constructive reasons require it. On account of rivet- driving clearances, a |-inch rivet can not be driven any closer than IJ inches to another member. Therefore, rivets can not be driven any closer to the stiffener than 1} inches, see Fig. 74. For this particular sized stiffener, the minimum spacings next to it will be 3i inches and 2-| inches as seen in Fig. 74. The rivet-spac- ing multiplication table, Table X, will be found very helpful in spacing the rivets here. Since the single gauge is used in the top flange and, according to the stress sheet, two rivet holes are taken out of each angle, it is possible to space the rivets in the outstanding leg and cover plates without reference to those in the other leg of the angle, due care being taken that they do not come closer than IJ inches to the out- standing stiffener leg. No special rule governs the spacing- in the cover plates, the only requirement being those of the specifications, and that the number of rivets from the center of the span to the end of the cover plate or the number of rivets from the end of one cover plate to the end of another shall be Fig. 74. Minimum Rivet Spacing for Stiffener Angles n= (net area of cover plate) s where n=the number required; ,9= the allowable unit flange stress; 102 STRUCTURAL DRAFTING and ?^=the value of a rivet in single shear or bearing in the cover plate, whichever is the smaller. For the first cover plate on top of the flange angles this equation gives n [(10 X A) - 2 (i + i) M X 10000 GO 13 = 13 which shows the number 78 to be amply sufficient in this respect. A clause in most specifications requiring the maximum spacing to be not greater than 16 times the thinnest plate and not greater than 6 inches, further governs the number, which would be 50 by this re- 1 I6"xf C.LI7 l6"Afx33'-6"7 V) (0 6"x6"x§"L5 (0 ( t ^ 1 ( 1 _„ , t== -^ 6'-// 6'-7r 4" ^^^--^ -^ __^^^ ^^-^^^ 3' ^^^-^^ ^^^^^ ■^^ 2' Fig. 75. Typical Stiffener and Rivet Spacing Diagram quirement. Most engineers, notwithstanding the specifications, re- quire the majority of the spacing to be within 5 inches. In case the spacing in the top flange is on a double-gauge line, care must be taken to see that the minimum stagger, Table IX, is not violated. In such cases it is customary to place a rivet in the inner gauge line of one leg opposite a rivet in the outer gauge line of the other leg, and to do this until a stiffener interrupts, when spacings are made with the observance of Table IX, until the rivets can be placed opposite again. STRUCTURAL DRAFTING 103 In order to Illustrate the above principles in regard to spacing when double-gauge lines are used on both legs and the maximum spacing for any particular distance is shown by the rivet curve, an example will be given. Let the stiffeners and the rivet-spacing diagram be as in Fig. 75. This shows the allowable rivet spacing to be 2| inches at the second, SJ inches at the third, and 3J inches at the fourth stiffener, the distance between stiffeners being Q'-7l". Let it be required to determine the rivet spacing between the second and fourth stiffeners C. PI. I6"x§"a33'-5" Top 8c Bottom 9 I "^ ^ -^ — f -4 — ^ d) ^ 6 -9 — iV =4. ^. 6'-z{ y i5(p)^f=5'-i^ 6-74 I" iJ^li 5 I" c' o I" ^^W75 ^1 0)34=3-84 3b 34 34 -€)■ . J-J"/77//7. distance— -^3' ■0- 6"x 6"x §" Ls i^ m in., dis tance -^3 ^ ■€)- Fig. 76. Detail Drawing Showing Determination of Rivet Spacing between Second and Fourth Stiffeners Since the stiffener angles have a 3-inch leg on the web, the gauge of which is If inches, and no rivet can be driven closer to the edge of the leg on the web or to the outstanding leg than \\ inches, no rivets can be driven closer to the gauge than 3 inches and 2\ inches on the sides of the outstanding leg and the edge of the other leg, respectively, see Fig. 76. Since 3 inches is the minimum distance it must be used at stiffener (2) notwithstanding the fact that the spacing diagram requires not less than 2| inches. This leaves (6'-7i") _3'' = 6'_4i" from that rivet to the one in the gauge at the top of stiffener (3), no attention being paid to 3 inches, the minimum dis- tance here, since it is less than the 3i inches required by the diagram. 104 STRUCTURAL DRAFTING An odd number of spaces must be used since the last rivet is on the other gauge line; and from the rivet -spacing diagram it is seen that the spacing can not exceed 2| inches until half way between the two stiffeners, and that a space or two of SJ inches would be allowed at stiff ener (3). By consulting Table X it is seen that 29 spaces at 2J inches are equal to G'-Oi''. Now (6'-4r)- (6'-Oi'0 = 3r or 15 fourths (V^), from which it is seen that if J inch was added to 15 of the 29 @ 2\" , the result would be all that is desired; but this would leave the last space 2f inches and by Fig. 76 it is seen that it must be at least 3 inches. By making the last space 3 inches, which is | inch, or f greater than 2J inches, there remain 28 spaces between 15 2 13 rivet a and rivet h, Fis". 76, and only = — left. If, there- ^ / 4 4 4 fore, J inch be added to 13 of the 2J-inch spaces, making 13 of 2\"-\-\"=?>^" each, the spacing will be correct. It is: 1 space at 3'' =0'-3'' 15 '' "2\"=?>'-l\" 13 " "2r=2'-lir _ 1 " -3'' =0'-3'' Total=6'-7i'' In a similar manner the second space between stiffeners has its rivet spacing determined. Here it is seen that the rivet spacing may start at 3J inches, can not exceed 3J inches until past the middle, and can have a few spaces at 3f inches at the stiffener. By Table X it is seen that 24 spaces at 3| inches equal 6-' -6''. Now {^'1\") — {^'-^") = l\" or |- and if one of the 24 spaces be increased | inch and two of them are increased | inch the entire |- inch will be used up and the spacing will have been completed. It is* 21 spaces at 3i"=5'-8i'' 1 " "3i"-0'-3i'' 2 " "3r=o'-7r Totals 6'-7i" In a similar manner almost any combination can be made to fill out any dimension. STRUCTURAL DRAFTING 105 The rivets in the horizontal flange of the angle and the cover plate are, when the spacing is greater than 2f inches, placed opposite those in the vertical flanges as is shown in Fig. 76, since according to Table IX, F being (2|''— f'0 = lF^ no stagger is required, and where the spacing is less than 2f inches it is changed so as to be 3 inches or more. In such cases as this it is not necessary to give spac- ing in the cover plates, a note, ^'Spacing same as in vertical legs" or "Spacing same as in web" being all that is required. After all the spacing in the cover plates has been determined, it may be necessary to change it slightly in order to allow for better spacing in the connection plates, but it is common practice to make the connection plates conform to the spacing in the cover plates since by so doing the additional cost of templets for the horizontal legs of angles is saved; and although a few additional templets for con- nection plates may be required the saving is considerable. Cover Plates. The actual lengths required are given on the stress sheet, but when the preliminary layout is made and the material ordered, the plates are ordered longer in order that they will at least be the required length when they are on the girder. The cover plates should be stopped so that the last rivet is IJ inches from the end, and in the case of double-gauge angles this rivet must be on the outer gauge, see Fig. 76. The single gauge is to be recommended, pro- viding sufficient rivets can be gotten in. At the ends of the cover plates it is not necessary to give the distances to the edges. The dimensions should go on as in Plate VIII and Fig. 76. The material notation should be put on as shown, all cover plates on both top and bottom, which are of the same section and length, being listed at the top. Any plate which is special to the bottom, is listed there. The beginner should be careful to note that the bottom cover plate next to the flange angles does not run the entire length of the girder, and accordingly he should not run his rivet spacing in the bottom flange through to the end but should stop at the end of the cover plate. This is a common error for beginners. Cross Frames. The cross frames may be detailed as shown in Plate VIII or as shown in Fig. 77. A layout of the plates must be made; the working point being taken at the intersection of the angle gauges, as in Fig. 77, or at some point which is approximately in the line connecting these points, see Plate VIII. The latter method 106 STRUCTURAL DRAFTING has the advantage in that it allows the point to be so chosen that the ends of the diagonals will be about | inch from both the stiffener and the top angle, thus making a smaller plate. The bevels are not stated on the diagonals since the dimensions are given directly. The end distances should be given or, if not, a note stating their value should be on the sheet. The distance, intersection to inter- section and end hole to end hole, should always be given, likewise the distance to the center of any group of holes. The rivet spacing may then be measured from these points. It was formerly customary to give the distance a, Fig. 77, but it is unnecessary and it is not now Fig. 77. Detailing of Cross Frames put on the drawing. Attention is called to the detailing of the diagonals in C. F. 1, the center line being half way between the gauges and a rivet placed on it at the ends. Rivet clearances should receive close attention. The first rivet in the horizontal leg of the top and bottom struts should be at least 1 J inches away from the edge of the cover plate, and it and all others should so stagger with those in the vertical flange that the field rivets may be driven. In case the frames are as in Plate VIII, the clearances of the rivets should be looked after and the spacing in STRUCTURAL DRAFTING 107 the cover plates be so arranged as to have one rivet on the gauge of the angle. In cases where there is not a cover plate or where the cover plate is thin, the tie may, on account of its being notched | inch, press down on the rivet heads of the cross frames. This may be avoided either by cutting out the tie or by placing fillers as shown in Fig. 77. Since the tie is notched at J inch and the head of a J-inch rivet is f inch, then the cover plate thickness added to that of the angle must be at least (iH-f) = li inches before a filler is required; and the thick- ness of the filler required in any case is t=H"-s where s is the sum of the thicknesses of the cover plate and flange angle, or flange angle alone in case there is no cover plate. Of course no filler is required at the bottom. All intermediate cross frames should be alike, and the end cross frames should be like each other. In Plate VIII, the angles are | inch and the first cover plate ^ inch, the sum being (J+ 3^) = li^ inches, which is greater than 1|, no filler is required. The top angles should have their horizontal leg detailed with the cross frame. This will save many dimensions on the lateral systems when they are detailed. Lateral Systems. The lateral systems should be detailed in place whenever possible. All the panels of- the lateral systems should be of the same length. If this is not possible, the shortest panels should be at the ends. It is seldom possible to make all the panels equal when a rolled-steel masonry plate is used. In case of the cast-steel pedestals, the dimensions of the top may be so chosen as to have all the panels of the lateral system equal. This will make the lengths of all angles with the same sized legs on connection plates equal. The angles may be detailed as shown in Plate VIII or as in Fig. 78. In either case the distance between intersections and between end holes must be given. The rivet spacing is measured back from these reference points, being determined from the layout of the plate. The distance from the working point out to the first hole should be given. The end distance should be given or else noted somewhere else. The plate should, when a double-gauge line is used, be made 108 STRUCTURAL DRAFTING to take in both rows of rivets; however, as mentioned before, the double-gauge Hne should only be used when unavoidable. The working point should be in the center of the web and on the gauge line of the stiffener angle when the method used in Fig. 78 is used, except in cases where a splice is used in the center of the girder, and then the intersection or working point should be at the center of the girder, see Fig. 73. All of the methods, Plate VIII and Figs. 78a and 78b, are in common use. The author prefers those Fig. 78. Detailing of Angles in Lateral Systems shown in 78b or Plate YIII. Sufficient clearance should be between the cross frame and stiff ener, see Fig. 78b. Each different angle, as in the case of stiffeners, should have a different mark. In such cases the mark is all that is necessary to designate another angle exactly like it, thus much repetition in detailing is avoided. The lateral systems, Plate VIII, are good examples of the efficient use of the marking system. The size of the connection plates is determined from the layouts, the rivet spacing and clearances all being taken from the layout also. STRUCTURAL DRAFTING 109 The edge distances of the working ends and edges are shown only when greater than 1 J inches, and in some cases even then the plates are kept rectangular throughout except in the case of the smaller ones. Few sizes for many plates give evidence of good detailing, and Plate VIII exemplifies this. It might be noted that with single gauge lines in the cover plates, the plates can be detailed more economically than when the double-gauge lines are used in the angles. A notch must be cut in the plates to allow the stiffener angle to clear. This must be carefully located and detailed for each plate where it differs in the least, and all plates to which any one notch applies should be noted directly with the detail. ^4?. •^i u /i /'■ /'-//' ^ /- ^ ^ "^ :^ Top Bearing for girders *^i,^ with 6" flange angles I'-ll" Top and Bottom Bearings Cast Steel Ig holes forl^ split bolls V^i^ ts te (£> is is Qy"^ — igr (^t^ugh^ harsJ"thic/{- 5" 3" /A^r Washer forged Ring To, fit snugly over turned shoulder on bearings Wrought Masonry Plate Rm wilh lamas nuts Fig. 80. Pin-Bearing Shoe and Rocker.s for Plate-Girder Bridges STRUCTURAL DRAFTING 111 Detailing of Compression Members. The first thing necessary is to determine the pin plates and the number of rivets required. This is done by a method already discussed. Fig. 81. Detail of a Two-Angle Compression Member The rivet clearances and also the clearances required in order that each member may fit in with the adjacent ones in the structure, should receive the most careful consideration. The compression members consisting of two angles riveted should be riveted together at distances throughout their length not greater than 12 inches. The clauses of the specifications relative to lattice bars, see Table XIV, and batten plates should be carefully read and followed. The dimensions necessary in compression mem- 14'- 5' I Wyyy' My/', l5altsps.at9"=9'-9" ^hy5" 198 b^-p ^Ls 5"j iSi 1 /< \ X :«; • V K ^■f; jV. L> F - ^ T A ■" > Oi YA^ ci: C^, Cb eT^ iV\ .... \r> It o^i ^ ' . ^ 1/ U j u -T \kv, (0 Qj "Si ■- r k y ^ 1 (r;-^ Ns,^ c::^ ^ < >v to Q. ^ r ^ •^ 1^.^ * \ >< \ ^ ijCfi i\ h^i ^ ^4J' '^^ ^•^1 !0 II ^^KV. * -j Y H 1 C^ •Cl&l "A^ ^ « ' 1 ^ 1 1 1 " ^ 1 5 '^ ^1 > K HF Ay T ^ ^ >c K. 1 ' T ,\ ^v >/ N(Vj . _ ^ n 0^ - ^^^ u C\ ^ n ^i t " c^ CL. -- * (^ \} o "v^ •^^ ri T S-. i^ , i ^ (T) ' ^ C\ ■^ (\ c t ^ ^ |l| ^1 ^^ \c :^ I v^ ^ V? 1 - V k - f J L 2 .,2 « ci fcD c.^ .-^ ■<^ efl •K hJ ^^i ^ to ^ T\ *\> fl o o O bD a a a o O 116 STRUCTURAL DRAFTING structure may be connected, made self-sustaining and safe in the shortest time possible. (2) Entering connections of any character should be avoided when possible, notably on top chords, floor beam and stringer con- nections, splices in girders, etc. (3) When practicable, joints should be so arranged as to avoid having to put members together by entering them on end, as it is often impossible to get the necessary clearance in which to do this. (4) In all through spans floor connections should be so arranged that the floor system can be put in place after the trusses or girders have been erected in their final position, and vice versa, so that the trusses or girders can be erected after the floor system has been set in place. (5) All lateral bracing, hitch-plates, rivets in laterals, etc., should, as far as possible, be kept clear of the bottom of the ties, it being very expensive to cut out ties to clear such obstructions. (6) Lateral plates should be shipped loose, or bolted on, so that they do not project outside of the member, whenever there is danger of them being broken off in unloading and handling. (7) Loose fillers should be avoided. They should be tacked on with rivets, countersunk where necessary. (8) In elevated railroad work, viaducts, and similar struc- tures, where longitudinal girders frame into cross girders, shelf angles should be provided on the latter. In these structures the expansion joints should be so arranged that the rivets connecting the fixed span to the cross girder can be driven after the expansion span is in place. (9) In viaducts, etc., two spans, abutting on a bent, should be so arranged that either span can be set in place entirely independent of the other. The same thing applies to girder spans of different depth resting on the same bent. (10) Holes for anchor bolts should be so arranged that the holes in the masonry can be drilled and the bolts put in place after the structure has been erected complete. In concrete masonry they should be set very carefully according to data furnished by the Bridge Company. (11) In structures consisting of more than one span a separate bed-plate should be provided for each shoe. This is particularly important where an old structure is to be replaced ; if two shoes were put on one bed-plate or twtr spans connected on the same pin, it STRUCTURAL DRAFTING 117 would necessitate removing two old spans in order to erect one new one. (12) In pin-connected spans the sections of top chords nearest the center should be made with at least two pinholes. On skew spans the chord splices should be so located that two opposite panels can be prected without moving the traveler. (13) Tie plates should be kept far enough away from the joints, and enough rivets should be countersunk inside the chord, to allow of eye bars and other members being easily set in place. (14) Posts with channels or angles turned out and notched at the ends should, whenever possible, be avoided. In conclusion, it may be said that the author has- wTitten this treatise vrith. the idea of preventing the beginner from falling into the more common errors of judgment, as well as helping him to become proficient in detailing according to good common practice. 7^ 1. INDEX J^ PAGE Angles 65 B Beams 72 Built-up tension members 112 C Compression members : Ill D Detailing (general instructions) 35 abbreviations 39 bolts, nuts, and washers .:...• 54 clearances 59 dimension and material notation 40 rivets and rivet spacing 45 Detailing, methods of . 65 angles 65 beams. 72 built-up tension members 112 combinations of structural shapes 71 compression members Ill facilitation of erection 112 plate girder spans , 87 plates 66 roof trusses 81 Drafting materials 6 Drafting room equipment and practice 1 assignment of work 3 ■ classification of drawings. 1 materials 6 ordering of material 12 allowances for bending 16 allowances for pin material 15 allowances for planing and cutting 15 layout 12 shop bills 17 personnel 2 records 4 stress sheet 11 M Materials 6 2 INDEX P PAGE Plate girder spans 87 Plates. . 66 R Records 4 Rivets and rivet spacing 45 Roof trusses 81 S Stress sheet 11 Structural drafting detailing (general instructions) 35 detailing methods 65 drafting room equipment and practice. . 1 T Table abbreviations 39 allowances for multiple lengths 16 allowances for pin material 17 allowances for single lengths 14 angles, standard gauges for 47 loop bars 58 0. G. washers, standard cast 55 rivet spacing, minimum . 45 rivet spacing multiplication table 52, 53 rivets, dimensions and conventional representation of . . . . 44 spacings, values center to center for various 49 staggers, minimum 50 thickness of lacing bars 72 W Work, assignment of 3 The School Behind the Book THIS practical handbook is one of the representatives of the American School of Correspondence. It is the only kind of representative by which the School reaches the general public and extends its educational work. The American School of Correspondence is chartered, under the same laws as a State University, as an educational institution. Its instruction books, v.ritten especially to suit the needs of men seeking self improvement through correspondence work, are reserved for its students and for class use in educational institu- tions; many of these texts are used in the class room work of the best resident schools in the country. However, in order* that t-he large number of ambitious men, for whom class work and correspondence study are neither prac- tical nor advisable, may not be deprived of this valuable material, it is published by the School both in sets covering the several branches that it teaches, and in a series of single Home Stud}/ volumes treating of specialized lines of practical knowledge. This book is a sample of the make-up of the Home Study volumes and the titles and authors are shovrn on the following page. By this method the School broadens its field of activity; and from these sales it derives an income to use in general educational work. The School's publications are clear and practical, and will be found ideal for reference and home reading. For those, how- ever, who desire more systematic study of the subjects in which they are particularly interested, the School advises a thorough course by correspondence as the quickest and surest means of obtaining the practical knowledge desired. The School offers correspondence instruction in all branches of architecture, civil engineering, college preparatory work, account- ing and business administration, drawing and design, electrical engineering, fire prevention and insurance, American law, mechan- ical, sanitary, and steam engineering, and textile manufacturing. It adapts its courses to the needs of the individual, b}^ starting him where his previous education stopped, and giving him only such work as is necessary to fit him for the work he vvants to do. On request the School will mail to an}^ address a Bulletin containing full information regarding its courses and methods. It emplo3"S no representative other than its own publications. AMERICAN SCHOOL OP CORRESFOiXDENCE CHICAGO, U. S. A, American School of Correspondence PRACTICAL HANDBOOKS FOR HOME STUDY OWING to a constant and increasing demand for low-priced single volumes covering the sub- jects treated in the courses and cyclopedias of the American School of Correspondence, a series of practical handbooks have been com- piled to be sold through the Book Stores all over the world. If any purchaser finds that his local dealer does not carry the particular title which interests him, he can order direct from the publisher, who will make shipment on receipt of price. If, after five days' examx- ination, the volume is found unsuited to his need, the purchaser may return it and his money will be promptly refunded. Partial List of Titles and Authors Alternating- Current Machinery William Esty $3.00 Architectural Drawing and Lettering Bourne-von Hoist- Brown 1 .50 Bank Bookkeeping Charles A. Sweetland-.. 1.00 Boiler Accessories Walter S. Leland 1.00 Bridge Engineering — Roof Trusses Frank O. Dufour 3.00 Building and Flying an Aeroplane Charles B. Hay ward 1.00 Building Superintendence Edward Nichols 1.50 Business Management, Part I James B. Grifhth 1.50 Business Management, Part II Russell-Griffith 1.50 Carpentry Gilbert Townsend 1.5D Care and Operation of Automobiles Morris A. Hall 1.00 Commercial Law • John A. Chamberlain 3.00 Compressed Air Lucius I. Wightman 1.00 Contracts and Specifications James C. Plant 1.00 Corporation Accounts and the Voucher System. .James B. Griffith 1.00 Cotton Spinning Charles C. Hedrick 3.00 Department Store Accounts Charles A. Sweetland _ . - 1.50 Descriptive Astronomy Forest Ray Moulton 1.50 Dynamo-Electric Machinery F. B. Crocker 1.50 Electric Railways Henry H. Norris 1.50 The Electric Telegraph - Thom-Collins 1.00 Partial List of Titles and Authors— Continued PRICE Electric Wiring and Lighting Knox-Shaad $1.00 Estimating -Edward Nichols 1.00 Factory Accounts Hathaway-Grlffith 1.50 Forging John Lord Bacon l.CO Foundry Work Wm. C. Stimpson 1.00 Freehand and Perspective Drawing Everett-Lawrence 1.00 The Gasoline Automobile Lougheed-Hall 2.00 Gas Engines and Producers 1 Marks- Wyer 1.00 Heating and Ventilation Charles L. Hubbard- 1 1.50 Highway Construction Phillips-Byrne 1.00 HydrauUc Engineering Turneaure-Black 3.00 Insurance and Real Estate Accounts Charles A. Sweetland 1.50 Knitting M . A. Metcalf 3.00 Machine Design Charles L. Griffin 1.50 Machine-Shop Work -- Frederick W. Turner 1.50 Masonry and Reinforced Concrete Webb-Gibson _' 3.00 Masonry Construction Phillips-Byrne 1.00 Mechanical Drawing Ervin Kenison 1.00 Modern American Homes H. V. von Hoist 3.00 Motion Pictures David S. Hulfish 4. CO The Orders Bourne-von Holst-Brov. n 3.00 Pattern Making James Ritchey 1.00 Plumbing Gray-Ball 1.50 Power Stations and Transmission Geo. C. Shaad l.CO Practical Aeronautics Chas. B. Hay ward 3.50 Practical Bookkeeping James B, Griffith l.^^O Practical Lessons in Electricity Millikan- Knox- Crocker - 1 .50 Reinforced Concrete Webb-Gibson l.CO Railroad Engineering Walter Loring Webb 3. CO Refrigeration M. W. Arrowwood l.CO Sewers and Drains A. Marston l.CO Sheet Metal Work William Neubecker 3.00 Stair-Building and Steel Square Hodgson- Williams 1.00 Steam Boilers Newell-Dow 1 .CO Steam Engines L. V. Ludy 1.00 Steam Turbines ^ Walter S. Leland 1.00 Steel Construction E. A. Tucker 1.50 Strength of Materials Edward Rose Maurer 1 .00 Surveying Alfred E. Phillips 1.50 Telephony Miller-McMeen - 4.00 Textile Chemistry and Dyeing Louis A. Olney 3.00 Textile Design Fenwick Umpleby 3.00 Tool Making Edward R. Markham _-_ 1.50 Valve Gears and Indicators L. V. Ludy 1.00 Water Supply Frederick E. Turneaure-. 1.00 Weaving H. William Nelson 3.00 Wireless Telegraphy and Telephony Ashley-Hay ward 1.00 Woolen and Worsted Finishing John F. Timmerman 3.00 Woolen and Wo'-sted Spinning Miles Collins 3.00 JUN lb 1:^13 Bill) •!" (til !*li