Reliability-based ductility reduction factors surfaces using the generalized bojorquez ground motion intensity measure IBg

Abstract

In this work, reliability-based ductility reduction factors surfaces are obtained through uniform annual failure rate (UAFR) spectra. For this aim, several nonlinear single degree of freedom (SDOF) systems that include various hysteretic behavior models, constant ductility performance and structural reliability levels are subjected to two sets of ground motions recorded on Mexico City. The first set includes 50 ground motion records located on stiff soils, while the second set correspond to 50 soft soil ground motions. In order to compute the UAFR spectra, the ground motion records were scaled at different values of a particular case of the generalized intensity measure IBg named INp for spectral acceleration. The study discusses the influence of different post-yielding stiffness on UAFR spectra obtained for the selected Bojorquez intensity measure, through the bilinear hysteretic model. Additionally, the Takeda model is used to represent structures that exhibit the effect of stiffness degradation. This study is aimed to compute the effect to obtain ductility reduction factors for various uniform annual failure rates, different degrees of post-yielding stiffness, and different ductility capacity for various nonlinear structures. The analyses of the results indicate that strength reduction (through ductility reduction factors) is mainly influenced by parameters such as ductility, failure rate, period of the system and soil conditions. Finally, reliability-based ductility reduction factor surfaces for stiff and soft soil are provided for different UAFR. It is important to say that this is the first time that ductility reduction factors are proposed based on IBg or INp as intensity measure.

Keywords

• Ductility
• Structural reliability
• Hysteretic behavior models
• Stiffness degradation
• Ductility reduction factors