The computer aided design of structural concrete sections subjected to combined loading

Abstract

The paper describes a Computer Subroutine that may be employed to design the reinforcing steel of reinforced and prestressed concrete sections subjected to vertical shear, lateral shear, vertical bending, lateral bending, torsion and axial load. The Subroutine, called DEVAST ( Design by the Variable Angle Space Truss) is based on a space truss model that is capable of predicting the post-cracking behavior of rectangular structural concrete sections subjected to combined loading. Since the space truss model can be used to predict the full post-cracking response of concrete beams under combined loading (i.e. strain in the longitudinal and web reinforcement, as well as the various deformations of the beam at all load levels), it is possible to predict the load combination that will result in yielding of either the longitudinal or the hoop steel. As a simple and conservative design criterion for use in Sub-program DEVAST, the reliable capacity of the section is taken as the load corresponding to first yielding of the steel. Although conceived as a Sub-program to be used in conjunction with a Main Program that performs the structural analysis, this Subroutine may very simply be modified for use as a self-contained design program. A listing of Sub-program DEVAST written in FORTRAN IV is provided in the paper.