Analysis of Tall Structures for Different Stiffness Ratios of Columns to Shear Walls and Column Shortening

Abstract

Differential axial shortening in a structure causes axial force redistribution among columns and walls, and introduces additional forces in the horizontal members such as beams and slab. Hence, it needs to be considered in the design, especially for medium to high-rise buildings. The best way to illustrate differential column shortening is to conduct floor-by-floor analysis, generally known as construction sequence analysis. Commercial software ETABS is available for conducting sequential analysis. The probable axial shortening could be important for construction engineers and project managers as well. This study presents a set of guidelines so that the effect could be taken into account approximately the preliminary design stage and also during the construction phase. In this study, construction stage analysis considers the creep and shrinkage effects of a 50-story building consist of an exterior concrete frame and interior shear walls. The displacements of vertical members are evaluated and compared with the results from conventional analysis (Without construction stage).

Keywords: Column shortening, stiffness ratio, creep, p-delta analysis