Design And Engineering Application Of Strengthed Connections In Steel Frame

Steel frame strengthed connections are new types of beam-column connections studiedmore and more by experts at home and abroad in recent years, the working principle isexpand local beam flange in a certain distance from the column surface, make the plastichinge form at the beam flange away from the weld between beam and column, reach thedesign purpose of plastic hinge relocation, effectively protect the weak parts of thebeam-column joints, improve the ductility of the structure, avoid brittle failure and realize thedesign thought of the seismic code “strong node weak component”.This article describes the research status at home and abroad in recent years on the steelframe beam-column connection, and give a rewiew on seismic study of weaken joints andstrengthed beam-column joints,and intruoduce the classification and the design methods ofsteel frame Joints. In the article the design steps and seismic performance of flange-platestrengthed node, cover-plate strengthed node,flange-expanded node and side-plate strengthednode were analyzed. With a12-storey steel frame design as an example, give a design ofstructure and joints under8degree earthquake, and the main research work of thearticle are asfollows:1, Introduce the seismic principles and construction features of the four strengthed nodes.in flange-plate strengthed node, cover-plate strengthed node, flange-expanded node andside-plate strengthed node,it is through the strengthening of the beam-colum connections toachieve the design ideas of strong nodes and the weak component and the relocationof plastic hinges,and avoid nodes of structure demaged firstly in strong earthquake.Inflange-plate strengthed connection and cover-plate strengthed node,strength the connectionperformance by welding reinforcing plates on the surface of the beam flange up and down;Inflange-expanded node, it is strength the connection performance byincreasing the width of beam flange of the nodes;And in side-plate strengthed node, it canstrength the connection performance by welding plates of the same thick as beam flange onthe sides of the beam flanges.The experiments showed that,those four strengthed nodes areable to achievethe purpose of the relocation of plastic hinge and improve the bearing capacity and seismic performance of node.2,According to our specification, summarizes the design principles andmethods of the four kinds of strengthed nodes,which Including the design requirements ofstrong colum and weak beam, weak components and strong nodes and the design of nodedomain,and checking of welds and bolts in connections, and gives the design methods andsteps of the four kinds of strengthed node which can provide a reference for related projects.3, With a12-storey steel frame design as an example, give a design of structure andjoints under8degree earthquake,and conduct a nonlinear time history analysis of ordinarynodes, cover-plate strengthed node and flange-expanded node under the earthquake waves ofTangshan and EI-Centro. Time history analysis showed that cover-plate strengthed node andflange-expanded node steel frame have the same overall trend of development of plastichinges as the ordinary nodes steel frame,which the plastic hinge appear in the first floor firstlyand continue to the upper, and finally the plastic hinge appear in the entire frame,andapproved a critical state of the structural collaps.The plastic hinge development of strengthednode frame si faster than the ordinary node frame,and the the overall deformation at Criticalstate is less than the ordinary node frame.It shows that the strengthed node can improve theelastic-plastic ductility and overall stiffness of the frame,which can avoid the brittle failureof structure and achieve the design idea of strong node and weak component in Seismicdesign codes...