Figure 7-2.-Typical small footing.Figure 7-3.-Reinforced concrete columns.FOOTING AND FOOTING REINFORCE-MENT.— Footings support the entire structureand distribute the load to the ground. The sizeand shape of a footing depend upon the designof the structure. In a small footing (fig. 7-2),“steel mats” or reinforcements are generallypreassembled and placed after the forms havebeen set. In large or continuous footings, such asthose found under bearing walls, steel mats areconstructed in place.COLUMN AND COLUMN REINFORCE-MENT.— A column is a slender, vertical memberthat carries a superimposed load. Concretecolumns, especially those subjected to bendingstresses, must always be reinforced with steel. APIER or PEDESTAL is a compressive memberthat is short (usually the height is less than threetimes the least lateral dimension) in relation to itscross-sectional area and carries no bending stress.In concrete columns, vertical reinforcement isthe principal reinforcement. However, a loadedcolumn shortens vertically and expands laterally;hence, lateral reinforcements in the form of lateralties are used to restrain the expansion. Columnsreinforced in this manner are called tied columns(fig. 7-3, view A). If the restraining reinforcementis a continuous winding spiral that encircles thecore and longitudinal steel, the column is calleda spiral column (fig, 7-3, view B).BEAM AND BEAM REINFORCE -MENT.— Beams are the principal load-carryinghorizontal members. They take the load directlyfrom the floor and carry it to the columns.Concrete beams can either be cast in place orprecast and transported to the jobsite. Figure 7-4shows several common types of beam reinforcingsteel shapes. Both straight and bent-up principalFigure 7-4.-Typica1 shapes of reinforcing steel.7-4
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