Analysis Of Mechanical Properties And Seismic Performance Of Steel Moment Connection With Welded Haunch And Cover Plate

Past earthquake happened all over the world, have great amounts of rigidconnections of steel frame damaged. The most common form of damage occurred in theinterface of the welding zone between beam and column flange. Post-earthquake manyresearchers about the traditional nodes were carried out by domestic and foreignscholars and the design concept of make the plastic hinge away from the connection waspresented. It could improved stress states on connection of welding seam base on theplastic hinge shift away from the surface of column and also avoided serious brittlefracturing in the welding zone. It is worth mentioning two methods to make the plastichinge away from the connection: using reinforced joints and reduced beam sectionconnection. By more than decade research, have demonstrated that those change canimprove the seismic performance of steel connections in different ways. There have twoforms for haunch connection: unilateral haunch and bilateral haunch of thebeam-column connection. Unilateral haunch connection could relief weld stressconcentration at haunch side of flange, while stress at the other side of beam flange islarger than normal connection. The main reasons of this phenomenon are that neutralaxis move to haunch side of unilateral haunch connection. So it’s will result brittlefractures easily at non-haunch side of flange. We could realize relocation of plastichinge in bilateral haunch connection, which can reduce weld stress focus and better thanunilateral haunch connection, as well as a good seismic behavior was shown. However,in practical engineering, some steel frame have high requirement, haunch in upper sideof beam lead to floor unevenness and visage will be affected.In this paper, a new connection joint of cover-plate-haunch connection was broughtforward on the basis of improving haunch connection and cover plate connection. Thiskind of connection joint not only overcomes the shortcomings that bilateral haunchconnections affect the flatness of floor and the interior appearance, but also strengthensthe connection performance. ABAQUS finite element software is used to study nodestress, plastic zone distribution, ultimate bearing capacity and hysteretic behavior. Theresult of new model is compared with past model. First,we can discuss the performanceof specimen in monotonic loading,which include force-displacement curve,ultimatebearing capacity,Von Mises stress distribution along stress paths, plastic strain of beamflange,plastic hinge forming mechanism and failure model.Then,we can study hysteretic behavior, ductility factor and equivalent viscous damping coefficient in low cycleloading.The results indicate that the new connection can effectively reduce stressconcentration on butt weld of the joint, make the plastic hinge away from theconnection and lower the possibility of brittle fracture. Therefore，the new connection istheoretically feasible and practical in application as well as excellent performance inearthquakes and the ideal energy dissipation.