Dynamic Analysis of High-Rise Structures with Outrigger Structural System Subjected To Lateral Loads

Abstract

In this age of urban development and rapid modernization the need of high-rise structures is rapidly increasing as buildings have gotten taller and narrower, the structural engineering has been increasingly challenged to meet the desired stability requirements. In tall buildings, stiffness is the key to sustainability, among various types of structural systems available for tall buildings, outrigger system is one of the majorly used efficient system. The present study aims to identify the efficiency of outrigger shear walls and to find out the optimum position of outriggers in high rise structures under lateral loads. The outrigger systems are required to have additional stiffness and adequate damping, by which outrigger can be used as a structural fuse to protect the building under severe earthquake and wind conditions.This research work aims to study the dynamic analysis of high-rise structures with outrigger structural system, for this research two regular buildings of 36 & 50 storeys situated in seismic zone V having a constant area of 900sqm(30mx30m) with a typical storey height of 3m were analysed using ETABS 2018. Optimum position of outrigger is determined by considering 8 models in which positions of outriggers is varied along the building height. Response spectrum analysis is carried out to evaluate the performance of structure for earthquake loads and the Gust factor method is used for the dynamic analysis of wind loads. Parameters such as Modal Mass Participation, Base Shears, Storey Displacements, Storey Drift, Time-periods, and acceleration are compared. Upon comparison it was found that among all 36 storey models outriggers placed at extreme ends performed better than other models and among all 50 storey models’ outriggers placed at regular intervals has performed better to all other models.