Analysts of cracking effects on tall reinforced concrete buildings

The design of tall reinforced concrete buildings must satisfy serviceabilit y criteria for lateral drift. It is therefore important to accurately asses s the lateral deflection of a structure to account for the nonlinear effect of cracking in concrete. Iterative procedures are necessary for this servi ceability analysis of tall reinforced concrete buildings, because the concr ete members that contribute to lateral stiffness have varying degrees of cr acking. Two procedures for the determination of lateral drift in reinforced concrete structures are presented in this paper. These procedures have bee n verified from the experimental data of tests on full-size structural suba ssemblages. Both procedures initially consider all the concrete members to be uncracked. An initial analysis then determines the cracked members and t heir stiffnesses are modified using probability-based effective stiffness r elationships. The redistribution of force and subsequent modifications of t he member stiffnesses are applied iteratively until convergence of the stru ctural response is obtained. These procedures are computationally more effi cient and direct than the general nonlinear finite-element method and are c ompatible with linear elastic analysis software that is commonly available in most structural engineering design offices.