BEARING PILES—A bearing pile is the same as awide-flange or H-beam, but is much heavier per linearfoot. Therefore, the dimension 14-inch (nominal depth)bearing pile weighs 73 pounds per linear foot. Note thatthis beam weighs nearly as much as the 24-inchwide-flange shape mentioned earlier.ZEE—These shapes are noted by depth, flangewidth, and weight per linear foot. Therefore, Z 6 x 3 1/2x 15.7 means the zee is 6 inches in depth, has a 3 1/2-inchflange, 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 theplate is 18 inches wide, 1/2 inch thick, and 2 feet 6inches long.FLAT BAR—This shape is a plate with a width lessthan 6 inches and a thickness greater than 3/16 inch.Bars usually have their edges rolled square. Thedimensions are given for width and thickness.Therefore, 2 1/2 x 1/4 means that the bar is 2 1/2 incheswide and 1/4 inch thickTIE ROD AND PIPE COLUMN—Tie rods andpipe columns are designated by their outside diameters.Therefore, 3/4 fTR means a tie rod with a diameter of3/4 inch. The dimension6 f, indicates a 6-inchdiameter pipe. Figure 7-2 illustrates the methodswhereby three of the more common types of structuralshapes just described are projected on a drawing print.MEMBERSThe main parts of a structure are the load-bearingstructural members that support and transfer the loadson the structure while remaining in equilibrium witheach other. The places where members are connectedto other members are called joints. The total loadsupported by the structural members at a particularinstant is equal to the total dead load plus the total liveload.The total dead load is the total weight of thestructure, which gradually increases as the structurerises and remains constant once it is completed. Thetotal live load is the total weight of movable objects,such as people, furniture, and bridge traffic, that theFigure 7-2.—Projecting structural shapes. A. I- or H-beam. B. Channel. C. Tee.7-3