Analysis on the Behaviour of Hybrid Outrigger System in Relation to the Frequency Content of Earthquakes

In this study, a hybrid outrigger system for lateral load resistance, consisting of a conventional outrigger and a virtual outrigger at two distinct floors, has been considered. The behavioural response of hybrid outrigger system varies with outrigger arm length variation, thickness of core and outrigger thickness. Frequency content of ground motions is a significant parameter that influences the dynamic behaviour of the structure and is used to express the damage caused in the structure due to earthquake. This study analyses the effect of high, intermediate, and low frequency content of earthquakes on the behavioural response of hybrid outrigger system assessed using the dependent parameters namely roof displacement, absolute maximum inter-storey drift and base shear for variations in thickness of core, outrigger arm length and outrigger thickness. Analytical models of heights 140m, 210m, and 280m having 40, 60 and 80 storeys respectively, are considered for the current study and the dynamic behaviour of the models are assessed using non-linear time history analysis. From the results, it is analysed that with increase in frequency content, there is a substantial change in the response values of the dependent parameters and, the sensitivity of the structure to frequency content enhances with an increase in the height of the building.