Consistent Procedure for Creep and Shrinkage Effects in RC Frames

Abstract

This paper describes a consistent procedure for determining creep and shrinkage effects in RC building frames. The procedure takes into account the sequential nature of application of dead load and the simultaneous nature of application of live load. Shearing action of beams is considered for evaluation of elastic axial forces as well as redistribution of axial forces resulting from creep and shrinkage deformations. In addition to elastic axial forces, the effect of inelastic axial forces on creep deformations, which get generated progressively with time, is also take into account. This procedure overcomes serious shortcomings of the most commonly used procedure, which is recommended to be used for buildings having low beam stiffness. A 60-story example frame is chosen, and results from the proposed procedure are compared with those obtained from the procedure available in the literature. It is shown that errors in the available procedure in differential vertical deflections (between adjacent columns) and column axial forces increase with higher beam stiffness. These errors are quite large even for low beam stiffness values.