Analytical Study to Identify the Optimal Outrigger- Shear Wall System in A Tall Building

Abstract

The rate of increase in human population especially in urban areas is caused due to the migration from rural regions for an economical uplift. Hence the construction of tall buildings has become crucial to maintain the cost effectiveness of the structures and minimal land usage. The prime duty of structural engineer is to design tall structures which are durable, safe and economical. Generally tall structures are vulnerable to lateral loads which are induced by wind and earthquakes. These forces are counteracted by the arrangement of coupled shear walls which is a common solution. But shear walls are not suitable and economical for structures taller than 20 storeys. Outrigger system is one such noticeable system in such cases with increased lateral stiffness and considered to be the most common and tangible solution for tall structures above 20 storeys. This paper presents the results of the study on displacement and base shear reduction by providing shear walls along with the outrigger system. Here RCC periphery  beams are used as outriggers at predetermined  heights0.25H, 0.5H and 0.75H in the  tall building under study andanalyzed for these three different locations along with the core shear wall. The structure is analyzedwith the software ETABS (''Extended Three dimensional Analysis of Building Systems''). Results show that double outrigger system at 0.5 H position can effectively reduce seismic response of the building with reduced displacement and  Shear.