CHAPTER 7 STRUCTURAL  AND  ARCHITECTURAL  DRAWINGS When you have read and understood this chapter, you should be able to answer the following learning objectives: Describe the elements of architectural drawings. Describe   the   elements   of   structural   steel drawings. Identify various types of construction drawings. Architectural and structural drawings are generally considered to be the drawings of steel, wood, concrete, and other materials used to construct buildings, ships, planes, bridges, towers, tanks, and so on. This chapter discusses the common architectural and structural shapes and symbols used on structural drawings, and describes the common types of drawings used in the fabrication and erection of steel structures. A building project may be broadly divided into two major phases, the design phase and the construction phase. First, the architect conceives the building, ship, or aircraft in his or her mind, then sets down the concept on paper in the form of presentation drawings, which are usually  drawn  in  perspective  by  using  pictorial  drawing techniques. Next, the architect and the engineer work together to decide upon materials and construction methods. The engineer determines the loads the supporting structural members  will  carry  and  the  strength  each  member  must have to bear the loads. He or she also designs the mechanical systems of the structure, such as heating, lighting, and plumbing systems. The end result is the preparation  of  architectural  and  engineering  design sketches that will guide the draftsmen who prepare the construction drawings. These construction drawings, plus  the  specifications,  are  the  chief  sources  of information for the supervisors and craftsmen who carry out  the  construction. STRUCTURAL SHAPES AND MEMBERS The  following  paragraphs  will  explain  the  common structural  shapes  used  in  building  materials  and  the common  structural  members  that  are  made  in  those shapes. SHAPES Figure 7-1 shows common single structural shapes. The symbols used to identify these shapes in bills of material,  notes,  or  dimensions  for  military  construction drawings are listed with typical examples of shape notations. These symbols are compiled from part 4 of MIL-STD-18B  and  information  from  the  American Society of Construction Engineers (ASCE). The sequence in which dimensions of shapes are noted  is  described  in  the  following  paragraphs.  Look  at figure 7-1 for the position of the symbol in the notation sequence.  Inch  symbols  are  not  used;  a  practice generally followed in all cross-sectional dimensioning of structural steel. Lengths (except for plate) are not given in the Illustrated Use column of figure 7-1. When noted, lengths are usually given in feet and inches. An example is 9´ - 2 1/4 . The  following  paragraphs  explain many of the shapes shown in figure 7-1. BEAMS—A beam is identified by its nominal depth, in inches and weight per foot of length. The cross section of a wide-flange beam (WF) is in the form of the letter  H. In the example in figure 7-1, 24 WF 76 designates a wide-flange beam section 24 inches deep weighing 76 pounds per linear foot. Wide-flange shapes are used as beams, columns, truss members, and in any other applications where their shape makes their use desirable. The cross section of an American Standard beam  (I)  forms  the  letter  I.  These  I-beams,  like wide-flange beams, are identified by nominal depth and weight per foot. For example, the notation 15 I 42.9 shows that the I-beam has a nominal depth of 15 inches and weighs 42.9 pounds per linear foot. I-beams have the  same  general  use  as  wide-flange  beams,  but wide-flange   beams   have   greater   strength   and adaptability. CHANNELS—A cross section of a channel is similar  to  the  squared  letter  C.  Channels  are identified by their nominal depth and weight per foot. For example, the American Standard channel notation 9        13.4 in figure 7-1 shows a nominal depth of 9 inches and a weight of 13.4 pounds per linear foot, Channels are principally used in locations where a single flat face without outstanding flanges on a side is required. However, the channel is not very efficient as 7-1