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 15 142.9 shows that the I-beam has a nominal depth of 15 inches and weighs 42.9 pounds per linear foot. 1-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 LJ 113.4 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

Figure 7-1.-Symbols for single structural shapes

a beam or column when used alone. But the channels may be assembled together with other structural shapes and connected by rivets or welds to form efficient built-up members.

ANGLES-The cross section of an angle resembles the letter L. Angles are identified by the dimensions in inches of their legs, as L 7 x 4 x 1/2. Dimensions of structural angles are measured in inches along the outside or backs of the legs; the dimension of the wider leg is given first (7 in the example). The third dimension is the thickness of the legs; both legs always have equal thickness. Angles may be used singly or in combinations of two or four angles to form members.

Angles also are used to connect main members or parts of members together.

TEES -A structural tee is made by slitting a standard I- or H- beam through the center of its web, thus forming two T-shapes from each beam. In dimensioning, the structural tee symbol is preceded by the letters ST. For example, the symbol ST 5 WF 10.5 means the tee has a nominal depth of 5 inches, a wide flange, and weighs 10.5 pounds per linear foot. A rolled tee is a manufactured shape. In dimensioning, the rolled tee symbol is preceded by the letter T. The dimension T 4 x 3 x 9.2 means the rolled T has a 4-inch flange, a nominal depth of 3 inches, and a weight of 9.2 pounds per linear foot.

BEARING PILES-A bearing pile is the same as a wide-flange or H-beam, but is much heavier per linear foot. Therefore, the dimension 14-inch (nominal depth) bearing pile weighs 73 pounds per linear foot. Note that this beam weighs nearly as much as the 24-inch wide-flange shape mentioned earlier.

ZEE-These shapes are noted by depth, flange width, and weight per linear foot. Therefore, Z 6 x 3 1/2 x 15.7 means the zee is 6 inches in depth, has a 3 1/2-inch flange, and weighs 15.7 pounds per linear foot.

PLATES-Plates are noted by width, thickness, and length. Therefore, PI 18 x 1/2 x 2'-6" means the plate is 18 inches wide, 1/2 inch thick, and 2 feet 6 inches long.

FLAT BAR-This shape is a plate with a width less than 6 inches and a thickness greater than 3/16 inch. Bars usually have their edges rolled square. The dimensions are given for width and thickness. Therefore, 2 1/2 x 1/4 means that the bar is 2 1/2 inches wide and 1/4 inch thick

TIE ROD AND PIPE COLUMN-Tie rods and pipe columns are designated by their outside diameters. Therefore, 3/4 0 TR means a tie rod with a diameter of 3/4 inch. The dimension O 6 0, indicates a 6-inch diameter pipe. Figure 7-2 illustrates the methods whereby three of the more common types of structural shapes just described are projected on a drawing print.

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