Seismic Load Analysis of different R.C. Slab Systems for Tall Building
Pages : 2034-2046
This Paper introduced the lateral analysis for tall buildings due to the seismic performance for different reinforced concrete slab systems. It study three systems, flat slab, ribbed slab, and panelled beam slab. The three systems are from the most attractive and commonly used floor systems, especially in high-rise constructions. In high seismicity regions, the declared non-ductile flat slab system poses a significant risk, brittle punching failure arises from the transfer of shearing forces and unbalanced moments between slab and columns that may trigger a progressive building collapse. This system is inherently flexible due to the non-rigid slab-column connections, and the building high aspect (height/width) ratio. Hence, in regions of high seismic risk, design codes recommended the use of slab-column frames to resist slabs, and require another stiffer system to resist lateral wind and seismic forces. From this standpoint, the choose of a system that provide rigid concrete slab than flat slab to resist lateral wind and seismic forces. This system is chosen to be the ribbed slab, and the panelled beam slab. These two systems of concrete slabs are ductile, and balanced moments between slab and columns. As the different types of seismic load resisting systems generally presented. Then, three systems of slabs performance for systems high-rise buildings during seismic loads are introduced. Some seismic design, analysis and performance assessment aspects of flat slab, and ribbed slab, and panelled beams systems for high-rise buildings are subsequently discussed. Finally, suggestions to improve the seismic performance of high – rise buildings horizontal members in slabs (ribs or beams-column) buildings are presented. ETABS version 9.5 is for analysis under lateral loads. ETABS is a programmer for linear, nonlinear, static and dynamic analysis, and the design of building systems. Multistory buildings constitute a very special class of structures and therefore deserve special treatment . The program is used to calculate the drifts for the systems and we noticed that the minimum drift was occurred in the ribbed slab system. So that, in high seismic risk regions, ribbed-slab-column frames is recommended to be gravity load resisting systems for building of high values of height/width ratios.
Keywords: Flat slab; Beam-column; Ribbed slab; Seismic load; Drift.
Article published in International Journal of Current Engineering and Technology, Vol.3,No.5(Dec- 2013)