Shear demand and inelastic displacement capacity of RC walls of different lengths forming a structural system

This article presents a study on the pushover response of four slender cantilever rectangular reinforced concrete (RC) walls of different lengths, analysed as independent elements (independent case), and forming a structural system with horizontal displacement compatibility at each storey level (system case). The aim is to investigate differences in the response of each of such walls under these two conditions, focusing on: the yielding top-displacement (Delta(y)); the base shear demand (V-0); and the ultimate top-displacement (Delta(u)). The walls were modelled using four approaches: lumped-inelasticity macro-elements with bilinear (BLM) and trilinear (TLM) skeleton; a strut-and-tie model (SAT); and a finite element model (FEM). Additionally, the paper introduces a novel analytical formulation for predicting the pushover-curves. The numerical results showed that the response of each wall differed for the independent and system cases. These differences increased for the shorter walls and were larger for the macro-models than for SAT and FEM. In the worst case, the system-to-independent ratios of Delta(y), V-0 and Delta(u), obtained with FEM were 0.55, 4.2, and 0.82, respectively. It is shown that the proposed analytical approach is able to accurately approximate the pushover-curves predicted with FEM for the system case. It is concluded that: the system effect should be considered in the seismic design of RC wall buildings; as the results obtained with the macro-models are in contradiction with FEM, their accuracy as a modelling approach is challenged; and analyses based on individual/independent walls in general, might not provide conservative estimates of their seismic response within a system.