Seismic Analysis of RC Framed Tall Structures with Plan Irregularity

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For the last few decades, architects, designers and structural engineers have focused on various advanced architectural aspects of reinforced concrete and steel structures. Regular plan buildings are quite commonly existent in India, while irregular plan buildings are in practice. These asymmetrical plan buildings, which are constructed in seismic prone areas, are most vulnerable and prone to subsequent damage during earthquakes. Seismic excitations generate the most destructive forces on structures. In accordance with newly revised Indian Code for Earthquake Provisons i.e. IS 1893:2016. In this present paper, high rise RC buildings have been modelled using a software package like STAAD.Pro V8i. Various models of irregular plans (e.g. U-, L-, T- and X-shaped) each of 25 storeyed (75 m each) have been taken into account. All the building models are located in high intensity seismic zone IV. As per IS 1893:2016, equivalent static analysis and dynamic response spectrum method have been conducted on all the building models. Even though various irregularities (such as torsional irregularity, stiffness irregularity) affect the seismic behaviour, this paper primarily concentrates on the effect of geometric irregularity on various RC structures. The paper also highlights both on which irregular shape of building plan gives the severe most response towards ground motion and also the accuracy of dynamic analysis conducted on high rise RC structures compared to static analysis.