Effect of location of thickened concrete slabs and type of material on the seismic behavior of structure buildings

Abstract

The design against lateral force (wind load and seismic load) is mandatory for high rise buildings. There are many factors that should be considered while estimating the seismic force that shall be applied to a building as well as certain checks to ensure building safety against that seismic force. Many structural engineers attempt to keep the seismic drift within the allowable value given by code of practice. The common problem is the seismic drift exceed the allowable values. Different solution is used to overcome this issue such as increasing in shear wall size, use larger size of beams, use thickened slab, use bracing, use advanced mass damper etc.. Practically, the idea of use thickened slab appears to author while design building with transfer slab. The more thickened transfer slab, the less seismic drift is obtained. This idea may not studied before from this point of view. Thus, this research focuses on the estimation of seismic behavior of concrete structures by performing many structure models with different heights at moderate seismic zones. The seismic force in this research is based on UBC97 code of practice. All the structural models have been analyzed and compared in similar circumstances. The research also attempts to find a practical solution which doesn’t need advanced technology by increasing the slab thickness in certain floors to reduce the seismic drift. The increase in slab thickness causes a complete change in all structural analysis results of a building (the total displacement and the total base shear). This research covers the results of increasing the slab thicknesses to obtain a good comparison between all models. Results show that the thickened slabs is good solution for seismic drift. The thickened slab should be located at certain floors to get the optimum reduction in seismic drift as well as the seismic drift shape of the structure. On the other hand, another approach using Ultra High Performance Concrete (UHPC) is used in certain floors without changing the slab thicknesses to observe the effect of using UHPC on the seismic behavior of structural building. Results of second approach show using of UHPC has a minor effect on the seismic behavior compared to results using the thickened slabs.