Analysts of cracking effects on tall reinforced concrete buildings

The design of tall reinforced concrete buildings must satisfy serviceability criteria for lateral drift. It is therefore important to accurately assess the lateral deflection of a structure to account for the nonlinear effect of cracking in concrete. Iterative procedures are necessary for this serviceability analysis of tall reinforced concrete buildings, because the concrete members that contribute to lateral stiffness have varying degrees of cracking. Two procedures for the determination of lateral drift in reinforced concrete structures are presented in this paper. These procedures have been verified from the experimental data of tests on full-size structural subassemblages. Both procedures initially consider all the concrete members to be uncracked. An initial analysis then determines the cracked members and their stiffnesses are modified using probability-based effective stiffness relationships. The redistribution of force and subsequent modifications of the member stiffnesses are applied iteratively until convergence of the structural response is obtained. These procedures are computationally more efficient and direct than the general nonlinear finite-element method and are compatible with linear elastic analysis software that is commonly available in most structural engineering design offices.