Development of a novel sacrificial‐energy dissipation outrigger system for tall buildings

Abstract

SummaryThe frame‐core tube‐outrigger structural system is widely used in tall buildings, in which outriggers coordinate the deformation between the core tube and the moment frame, leading to a larger structural lateral stiffness. Existing studies indicate that outriggers can be designed as “fuses” of tall buildings through dissipating seismic energy after yielding, to protect the main structure. To date, both conventional and buckling‐restrained brace (BRB) outriggers have been applied in practice. Subjected to the maximum considered earthquake (MCE), the hardening effect of BRB outriggers increases the damage of other structural components. Meanwhile, conventional outriggers are difficult to repair, owing to the local buckling‐induced severe deterioration and damage. To overcome these problems, this study proposes a novel sacrificial‐energy dissipation outrigger (SEDO) to improve the seismic resilience of tall buildings. The chords of SEDO are made of high‐strength steel and remain elastic. The inclined braces of the SEDO are composed of a sacrificial part and an energy‐dissipating part. Therefore, the SEDO remains elastic under design‐based earthquakes (DBEs) and dissipates inelastic energy under MCEs. Moreover, the detailing of this novel SEDO is proposed on the basis of experimental studies. The optimal strength ratio between the sacrificial part and the energy‐dissipating part is determined in the range of 6:4 to 4:6 on the basis of nonlinear time history analyses (THAs) and parametric studies. Afterwards, the SEDOs are used in an actual tall building to verify their seismic performances through nonlinear THAs. The results indicate the proposed SEDO is able to protect other structural components and effectively improve the seismic resilience of tall buildings.