Experimental Research On Cover-plate Reinforced Of Box Strengthen-joint Region Connection For Weak Axis Of I-section Column Under Monotonic Loading

Currently research on connecting of I-shaped column in weak axis has remained ratherlimited, to bring greater difficulties, Code for Design of Steel Structures ((in China) is alsolack of substantive guidance. To solve these problems, associate professor Linfeng Lu fromChang’an University proposed a new joint with box strenthen region in weak axis, it isdesigned to improve mechanical behavior of connecting of I-shaped column in weak axis,then,it can also provide reference for further study, practical application and preparation ofthe design code related to connection in weak axis.4full-scale specimens of new box-type joint in weak axis was designed under monotonicloading test.4specimens are: non-cover-plate reinforced normal connection and it’s relativeone with slab, cover-plate reinforced connection and it’s relative one with slab. The stressdistribution of joint region, pedal,flange and web of steel beams were recorded bydisplacement transducers and strain gauge.The main objective of this test is to investigate thebasic performance of initial rotational stiffness, yield load, ultimate load, maximum plasticrotation angles and ductility. By analysis and comparison of these basic mechanicalproperties, we can draw to conclusions as follows:1.Results showed that the proposed new box-type joint has strong joint region whichremained in elastic during the entire process of loading test, and the local box structuresignificantly solve the problem of the weak of joint region of weak axis direction, which canmake great contribution to the mechanical properties of the joint region.2.The yield load of the specimen, whose beam reinforced with cover plate is20%largerthan the unreinforced one respectively, and the all specimens, whose ductility index is not lessthan4, can meet the requirements of design code. The application of cover plate can makesure that the plastic hinge appeared at the predetermined location.3.Composite slab has little effect on bearing capacity and ductility of joint, this is mainlybecause that anchorage between the slab and the column is not sufficient, which makesdistributions of force is not effective.4.According to classification standard about stiffness and strength of joint, fourspecimens all belonged to rigid connection in frame without sidesway and semi-rigidconnection in frame with sidesway.5.Results from strain gauge indicated that, in the connecting position of the top flangeand the column,the stress distribution was the form of "middle small, on both sides of thebig" along the direction of the beam’s width. 6.The stress around the connection between covering plate and beam is relativelyhigh,and high strength covering plate is relatively advised.Finally, the paper points out some difficulty unsolved in the testing and thecorresponding advice is given. The subsequent research is also discussed.