THE APPLICATION OF THE EQUIVALENT LINEARIAZATION METHODOLOGY IN SELF-CENTERING BUCKLING-RESTRAINED BRACED FRAMES

A Self-centering Buckling-restrained Brace(SCBRB) consists of a self-centering system and energy dissipating cores. It combines the merits of both self-centering brace and Buckling-restrained Brace. Thus, it can help to realize the resilience of a structure if properly designed. Once the main frame can maintain elastic under the expected earthquakes, the restoring force model of an SCBRB frame(SCRBRF), which is the combination of the bilinear elastic and bilinear elastoplastic model, is trilinear. Since the precision of the Equivalent Linearization Methods(ELM) is dependent on the calculation method of the equivalent damping ratio and equivalent period, and is also sensitive to the hysteretic model, the result of the Equivalent Linearization Method for SCRBRF may need correction for better evaluation. Firstly, parametric study of the mean difference and the standard deviation of the difference between seismic displacement obtained by two ELMs and nonlinear Response History Analysis have been performed. Result shows that displacement calculated using the two ELMs for SCBRBFs is generally more accurate, especially for T> 3 s, when compared with elastoplastic hysteretic model. This could be attributed to decreased nonlinearity and plasticity in SCBRBFs. The ASD Method is more accurate than the R-H Method as the former considers the contribution of all displacement that the structure has experienced when calculating the equivalent period and equivalent damping ratio. Secondly, correction factor of different ELMs for the evaluation of displacement has been recommended. Finally, the effect of the key parameters on the equivalent damping ratio has been investigated according to the function of the damping ratio and the optimum ductility ratio has been presented for SCBRBF.