Investigation of the Effect of Shear Wall Curtailment for Medium and High-Rise Buildings in Seismic Region
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Date
2024-04
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Addis Ababa University
Abstract
In this thesis work, the effect of shear wall curtailment for medium and high-rise buildings in seismic region is investigated. When the shear wall frame system is loaded laterally in medium and high-rise buildings, the upper part of the shear wall takes a negative role in resisting the lateral loads because of the difference in the free deflected forms of shear walls and moment resisting frame. The discontinuity of shear walls may prove an effective technique in reducing this negative effect at the top. Consequently, in order to have good wall-frame interaction, a shear wall should be curtailed above a point on which the shear wall is not effective in reducing the seismic responses of shear walls.
Analysis is done for six G+10, seven G+20, and ten G+30 models using finite element method (FEM) of response spectrum analysis with respect to the seismic response parameters such as top story displacement, story drift, story shear, base moment and fundamental time period. Moreover, the Finite element analysis (FEA) is tried to be supplemented by three continuum methods (algebraic solutions) which includes the Component Stiffness Method-Equation C, Alex Coull’s method and Marie-José Nollet’s method.
In the FEA and continuum analysis results, the maximum top story (roof) displacement where the shear wall is curtailed above 8th, 14th and 22nd floor for the G+10, G+20 and G+30 building models respectively do not significantly vary with respect to that of the full height shear wall-frame models. Moreover, the other parameters (i.e., the story drift, story shear, story overturning moment, story stiffness and fundamental time period) also reveal that curtailment of shear wall above 70% - 80% of the height of the building will not much affect the performance of the building in resisting seismic loads.
Therefore, even if ES-EN 1998: 2015 recommend shear walls to continue up to the roof level for the sake of regularity (i.e., the analysis will be simplified and the structure response will also be easily predictable), curtailment of the shear walls in the top floors is not necessarily detrimental to the performance of the structure. When building height increases, the stiffer the frames will be, the greater the interaction become between wall and frame and the lesser the contribution of the shear wall. So, if we curtail the shear wall for the increased building height (high rise), since the shear wall contribution is minimized, the curtailment become safe.
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Shear Wall Curtailment, for Medium and High-Rise Buildings, Seismic Region