Analytical study of hybrid outrigger system on high-rise reinforced concrete structures

In this study, hybrid outrigger structures, ranging from 40-85 storey, are subjected to wind and seismic loading. The hybrid system consists of one virtual outrigger and one conventional outrigger. The position of these outriggers is varied along the building height. The parameter a is a combination of the thickness of the core, area of the columns, and the distance between the core to the peripheral columns. a is varied over a specific range and the optimum location of outriggers for each a value is studied. The response reduction, namely the lateral top displacement, drift, bending moment, shear force, and acceleration due to the system is assessed. These structures are modelled and analysed using a finite element software, ETABS, for static and dynamic analysis. Dynamic analysis is conducted by time-history analysis. The results indicate that the effect of hybrid outriggers is similar against uniform and trapezoidal loadings, and the lateral displacement reduction is least against parabolic loading. The optimum range of the hybrid outriggers has been mentioned. Furthermore, it was found that the hybrid outrigger system is more efficient than a conventional outrigger system as the height of the building increases.