Optimal drift design of tall reinforced concrete buildings with non-linear cracking effects

This paper presents an efficient, computer-based technique for the optimum drift design of tall reinforced concrete (RC) buildings including non-linear cracking effects under service loads. The optimization process consists of two complementary parts: an iterative procedure for the non-linear analysis of tall RC buildings and a numerical optimality criteria (OC) algorithm. The non-linear response of tall RC buildings due to the effects of concrete cracking is obtained by a series of linear analyses, the so-called direct effective stiffness method. In each linear analysis, cracked structural members are first identified and their stiffness modified based on a probability-based effective stiffness relationship. Stiffness reduction coefficients are introduced as measures of the remaining stiffness for structural elements after cracking. A rigorously derived OC method is developed to solve for the minimum weight/cost design problem subject to multiple drift constraints and member sizing requirements. A shear wall-frame example is presented to illustrate the application of this optimal design method. The design results of the optimized structure with cracking effects are compared to those of the linear-elastic structure without concrete cracking. Copyright (c) 2005 John Wiley & Sons, Ltd