۱- Introduction

۲- Basic design considerations

۳- Prototype structure configuration

۴- Finite element model

۵- Seismic performance assessment

۶- Results and discussions

۷- Summary and conclusions

References

Abstract

Steel-timber hybrid structural systems offer a modern solution for building multi-story structures with more environmentally-friendly features. This paper presents a comprehensive seismic performance assessment for a kind of multi-story steel-timber hybrid structure. In such a hybrid structure, steel moment resisting frames are infilled with prefabricated light wood frame shear walls to serve as the lateral load resisting system (LLRS). In this paper, drift-based performance objectives under various seismic hazard levels were proposed based on experimental observations. Then, a numerical model of the hybrid structure considering damage accumulation and stiffness degradation was developed and verified by experimental results, and nonlinear time-history analyses were conducted to establish a database of seismic responses. The numerical results further serve as a technical basis for estimating the structure’s fundamental period and evaluating post-yielding behavior and failure probabilities of the hybrid structure under various seismic hazard levels. A load sharing parameter was defined to describe the wall-frame lateral force distribution, and a formula was proposed and calibrated by the time-history analytical results to estimate the load sharing parameter. Moreover, earthquake-induced non-structural damage and residual deformation were also evaluated, showing that if designed properly, desirable seismic performance with acceptable repair effort can be obtained for the proposed steel-timber hybrid structural system.

Introduction

In recent devastating earthquakes around the world, many buildings suffered severe damage, leading to huge social and economic losses. The 2008 Wenchuan earthquake in China, with a magnitude of Mw 8.0, caused approximately $130 billion USD in property losses [1]. The post-earthquake survey revealed that casualties were primarily caused by the collapse of masonry or concrete buildings with large seismic mass and poor construction quality. The 2011 Christchurch earthquake in New Zealand, with a magnitude of Mw 6.3, caused 185 deaths, and the central city of Christchurch was badly affected with severe damage to buildings and infrastructures that were already weakened by the preceding Canterbury earthquake, with a magnitude of Mw 7.1, in 2010 [2]. Experiences from past major earthquakes demonstrated that relatively lightweight timber or timber-based buildings kept more people safe. To provide an alternative for multi-story building systems in seismicprone zones, a steel-timber hybrid structure was proposed by He et al. [3] and Li et al. [4]. In such structures, the steel moment-resisting frames are infilled with prefabricated light wood frame shear walls to serve as the lateral load resisting system (LLRS), and the diaphragms are composed of C-shaped steel joints and dimension lumber decking. The weight of the proposed structural system is largely reduced with the application of wood assemblies; thus, the seismic action on the entire building is also considerably reduced.