Optimization Of Reduced Beam Section Moment Connections

Abstract

Reduced beam section (RBS) moment connections also referred to as Dog-bone connections\nare commonly used in seismic resistant steel moment frames. In RBS connections, the top and\nbottom flanges of the steel beam are selectively trimmed in the area adjacent to the beam to\ncolumn connection. This is to ensure that under seismic loading, plastic hinges are formed in\nthe beam not in the column. The purpose of this study is to optimize the cyclic responses of RBS moment connections\nincluding those with sloping beams. Using a response surface method, predictive equations are\ndeveloped for the response characteristics, such as initial stiffness, plastic strain index, moment capacity, hysteretic energy dissipation, and strength degradation rate. The optimization studies\nconsider objectives leading to higher stiffness, lower plastic strain index, maximum moment\ncapacity, higher hysteresis energy dissipation and lower strength degradation. The optimization\nresults obtained shows that beam slope angle greater than 27.8° will experience fracture, high\ninelastic demand with higher strength degradation and more intense buckling.