Rocking shear wall foundations in regions of moderate seismicity

[摘要] ENGLISH ABSTRACT: In regions of moderate seismicity it has been shown that a suitable structural system iscreated when designing the shear wall with a plastic hinge zone at the lower part of thewall, with the shear walls resisting lateral loads and all other structural elementsdesigned to resist gravity loads. A suitably stiff foundation is required for theassumption of plastic hinge zones to hold true. This foundation should have limitedrotation and should remain elastic when lateral loads are applied to the structure.Ensuring a foundation with a greater capacity than the shear wall results in excessivelylarge shear wall foundations being required in areas of moderate seismicity forbuildings with no basement level.This study aims to investigate the feasibility of reducing the size of shear wallfoundations in areas of moderate seismicity for buildings with no basement level. Theinvestigation is aimed at allowing shear wall foundation rocking and taking into accountthe contribution of structural frames to the lateral stiffness of the structure. An examplebuilding was chosen to investigate this possibility.Firstly, lateral force-displacement capacities were determined for a shear wall and aninternal reinforced concrete frame of this investigated building. Nonlinear momentrotationbehaviour was determined for the wall foundation size that would traditionallybe required as well as for six other smaller foundations.The above capacity curves against lateral loads were then used to compile a simplifiedmodel of the structural systems assumed to contribute to the lateral stiffness of thebuilding. This simplified model therefore combined the effect of the shear wall, internalframe and wall foundation.Nonlinear time-history analyses were performed on this simplified model to investigatethe dynamic response of the structure with different wall foundation sizes. By assessingresponse results on a global and local scale, it was observed that significantly smallershear wall foundations are possible when allowing foundation rocking and taking intoaccount the contribution of other structural elements to the lateral stiffness of thebuilding.

[发布机构] Stellenbosch University