Systematic Analyses of Substructures

Abstract

Substructure system is composed of horizontal and vertical components. The former mainly refers to slabs, beams, secondary beams, primary beams, and trusses. Slabs and trusses could be treated as beams in approximate calculation. Generally, horizontal components bear distributed or concentrated loads along their length within the plane. Concentrated reactions at supports, along with vertical loads, generate shear forces, bending moments, and sometimes torques or axial forces in horizontal components. In the early stage of design, since torques or axial forces that horizontal components undertake are of small magnitude, the influence of these forces could be ignored. Major attention should be paid to structural resistance to shear forces and bending moments. Horizontal components made of steel commonly have cross sections shaped as I, H, L, T, round, or square tube. As for concrete horizontal components, rectangle, T, H, round, or square are popular choices when it comes to the selection of shapes of cross section.