Plastic Deformation of Beams in Steel Moment Frames Subjected to Strong Earthquakes

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This project is concerned with the demand for ductility of beams in steel moment frames. The results from this project are summarized as follows :1.Numerical response analysis is carried out for 15 frames against a variety of ground motions. In this study, maximum plastic rotation, maximum increment of plastic rotation during a half-cycle of vibration, and the range of variable plastic rotation are considered as the parameters that represent the magnitude of plastic deformation. The results are summarized as formulas to predict those parameters based on maximum story drift angles.2.Based on the above-mentioned numerical results, we deal with hysteretic behavior. Cumulative plastic rotation, the increment of plastic rotation during each half-cycle of vibration, and the hysteretic process of plastic rotation are discussed. A method is proposed to approximate damage to the beams in steel moment frames subjected to strong ground motions.3.A computer program is developed based on the one-dimensional finite element method in which a generalized constitutive relationship considering isotropic hardening and kinematic hardening is incorporated. Numerical analysis of steel wide-flange beams is carried out under various loading sequences similar to seismic response. The results are summarized as a method to predict the maximum bending moments of beams, taking into account the maximum story drift angles.