Fragility Assessment of Combined Heavy Timber-Steel Bracing System Through Hybrid Simulation

This study performs a fragility assessment of a combined heavy timber-steel friction braced framing system through hybrid testing. In this study, one bottom storey bay of a 7 storey prototype structure is physically tested in the laboratory while the remaining lower bays and the upper 6 storeys are modeled numerically in OpenSees. One hundred and sixty five hybrid tests are performed through incremental dynamic analysis and fragility curves are developed to estimate the probability of damage at varying seismic intensities. The prototype structure is assessed at various performance levels including design and maximum credible hazard levels. The results from the hybrid test are compared with the results from the purely analytical simulation to assess the accuracy of the current finite element modeling techniques. Results show good agreement up to 2.0 percent maximum interstorey drift. The modeling system exhibits predictable behaviour and experimental results indicate the model is conservative.