Proposing two new methods to decrease lateral-torsional buckling in reduced beam section connections

Reduced web section(RWS)connections can prevent lateral-torsional buckling and web local buckling experienced by reduced beam section(RBS)connections.In RWS connections,removing a large portion of web can result in shear demand intolerance induced to plastic hinge region.The present study aims to resolve the problems of RBS and RWS connections by proposing two new connections:(1)RBS with stiffener(RBS-ST)and(2)RBS with reduced web(RW-RBS)connections.In the first connection(RBS-ST),a series of stiffeners is connected to the beam in the reduced flange region,while the second connection(RW-RBS)considers both a reduction in flanges and a reduction in web.Five beam-to-column joints with three different connections,including RBS,RBS-ST,and RW-RBS connections were considered and simulated in ABAQUS.According to the results,RBS-ST and RW-RBS connections can decrease or even eliminate lateral-torsional buckling and web local buckling in RBS connection.It is important to note that RWRBS connection is more effective in long beams with smaller shear demands in the plastic hinge region.Moreover,results showed that RBS and RW-RBS connections experienced strength degradation at 4%to 5%drift,while no strength degradation was observed in RBS-ST connection until 8%drift.