Gravity-induced shear force in reinforced concrete walls above transfer structures

Abstract

In this study, the gravity loads in reinforced concrete shear walls supported on transfer structures are investigated.Emphasis is placed on the shear-stress concentration effects on the supported shear walls owing to the distortion of the transfer structure. A simplified model is proposed to illustrate the fundamental physical interactions. Finite-element analysis is also conducted to study the influences of the symmetric and asymmetric shear-wall arrangements, positioning of supporting columns and span-to-depth ratio of the transfer structure. Non-linear behaviours encompassing the use of yielded stiffness at ultimate limit state, sequential construction and the creep of reinforced concrete under gravity loads are addressed. Various effects of modelling assumptions and simplifications on the stress redistribution of the transfer structure are investigated. Remedial measures are proposed, such as increasing the depth of the transfer girders using late-cast slabs, segmented upper shear walls and concrete of higher grade for critical regions.

Simplified seismic assessment of buildings using non-uniform Timoshenko beam model in low-to-moderate seismicity regions

“…in which A x denotes the total shear area = sum of wall and column areas at the ground level which contributes to the shear resistance (assumed in the x-direction here), and a reduction factor of 0.8 (cl.11.9.4 in ACI318-11) is assumed to account for the effective depth of walls; Ω = 1.5 denotes the load factor (overstrength factor) for the [59,70], in which gravity-induced shear stress = 2 to 3 MPa is assumed for the critical walls supported above the transfer [71]. The λ R factor accounts for possible stress concentration effects on a single wall or column attributed to: (a) plan irregularity and (b) shear stress concentration on supported walls due to the transfer plate warping effect.…”

Editorial

“…First, Tang and Su (2015) report the results of a numerical investigation using finite elements to analyse the influence of gravity loads on RC shear walls that are supported on transfer structures. Shear stress concentrations induced on the shear walls due to deformation of the transfer structures are shown to arise from the loads.…”