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Seismic analyses of concrete structures under maximum-considered earthquakes require the use of reduced stiffness accounting for cracks and degraded materials. Structural walls, different to other flexural dominated components, are sensitive to both shear and flexural stiffness degradations. Adoption of the gross shear stiffness for walls in seismic analysis prevails particularly for the design codes in the US. Yet available experimental results indicate that this could overstate the shear stiffness by more than double, which would hamper the actual predictions of building periods and shear load distributions among columns and walls. In addition, the deformation capacity could be drastically understated if the stipulated constant ductility capacity is adopted. This paper reviews the available simplified shear and flexural models, which stem from classical mechanics, empirical formulations and/or parametric studies, suitable for structural walls at the state-of-the-art. Reviews on the recommended flexural and shear stiffnesses by prominent design codes such as ACI318-11, Eurocode 8 and CSA are included. A database comprised of walls subjected to reverse-cyclic loads is formed to evaluate the performance of each model. It is found that there exist classical models that could outweigh overconservative codified values with comparable simplicity for practical uses.

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.

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