Studies on damped hybrid outrigger systems of composite walls and steel bracings

Abstract

Both experimental and numerical investigations were conducted on a new type of steel–concrete hybrid outrigger system developed for high-rise building structures. The steel bracing is embedded in the reinforced concrete outrigger wall, and the steel bracing and concrete outrigger wall work together to enhance the overall structural performance of tower structures under extreme loads. At the same time, metal dampers of a low-yield steel material are used as a ‘fuse’ device between the hybrid outrigger and the column. The damper is engineered to be ‘sacrificed’ and yield first in moderate to severe earthquakes to protect the structural integrity of important structural components of the hybrid outrigger system. Thus, brittle failures are unlikely to occur due to severe cracking in the concrete outrigger wall. A comprehensive experimental research programme was conducted to examine the structural performance of this new type of hybrid outrigger system. Finite-element models were also proposed and verified to be able to conservatively predict the structural performance of the hybrid outrigger system in both elastic and non-linear plastic stages. The key component and overall system tests were examined, which reveal the detailed structural response under various levels of static and cyclic loads.