EXPERIMENTAL STUDY ON THE BEAM HINGE MODEL AND CAPACITY FRAGILITY OF FORTIFIED FRAMES

Higher seismic fortification grades require higher seismic capacity of the building. However, mechanical models and parameters that can reflect fortification capacity differences are limited in practice. This study aims to obtain the constitutive models and probabilistic capacities of RC frame beam hinges from tests, which is important for the seismic risk study of the whole structure. For this purpose, 4 groups with 12 reduced scale joint models that conform to GB50011-2010 with different fortification levels and locations were made and subjected to pseudo-static tests. The test results showed that failure of joints was essentially bending failure of beams; the locations of joints did not influence the strength and deformation indices of beams. Therefore, the number of beam hinge samples could be expanded several times from limited test specimen, which increased the precision of probability analyses. Thus, based on statistical results and with reference to FEMA 356, beam hinge models of different fortification levels were extracted; performance indices to different damage states were proposed; model parameter reliabilities were calculated; and fortification gradients and fragility gradients were summarized. Quantifying structural models by the code requirements while assigning the model parameters with reliabilities by means of structural tests are the main innovation of this study.