Civil Engineering Association

Pushover analysis of multi-st orey cantilever wall systems

Mid- to high-rise buildings are often braced by slender reinforced concrete (RC) walls, which are coupled by RC floor diaphragms. In design it is typically assumed that the walls act independently and the design base shear demand is computed neglecting any compatibility forces between the walls. Pushover analysis of systems
comprising walls of different lengths have, however, shown that large compatibility forces can develop between walls of different length, which should be considered in design, but also that the magnitude of the computed forces is very sensitive to the modelling assumptions. The paper explores by means of a case study of an eight storey structure with two walls of different lengths the shear forces developing at the base of the wall. It compares and discusses the analysis results from different models including simple hand calculations, a lumped plasticity beam element model and a complex shell element model. It concludes that numerical and analytical approaches which are based on the lumped plasticity model tend to overestimate the shear force demand on the shorter wall.