Experimental Research On Reduced Beam Section Of Box Strengthen-joint Region Connection For Weak Axis Of I-section Column

It was the plenty of brittle fracture of steel structure joint found in Northridge andNanbu-Kobe earthquake that has brought widely attention to the engineering and academicfield, and relative research for steel structure joint has been deepen and improved. In thispaper, on the basis of the previous research, the basic mechanical properties of reduced beamsection of box strengthen-joint region connection for weak axis of H-shape column wasstudied through test, and the influence of slab on the joint properties was investigatedsimultaneously.Four full-scale specimens of box strengthen-joint region connection for weak axis ofI-section column of fringe frame was designed, two of whicd were normal type and the othertwo were reduced beam section (RBS) type. Each type included one specimen with slab andthe other not. All specimens were designed in accordance with the relevant provisions ofChina’s current specifications, and RBS joint weakening parameters were checked byreferencing the U.S. specification AISC358. Before the test, non-linner analysis was made byANASYS12.0to determine the reasonableness of the test plan.The failure mode and the emergence and development law of the plastic hinges, the staindistribution along the length and width of beam, stain distribution of panel zone andcovering plates for all specimens were obtained by monotonic loading test. By analysis of thedata obtained from the test, P curves, M curves, curves, ductility factor andplastic chord rotation angle for the specimens were achieved, and relative conclusions can bedrawn as follows: The panel zone strengthened by box-region was demonstrated as strongstrong panel zone for it maintained elastic during the whole loading process. High stress wasgauged at the connection of covering plate and beam, and to avoid laminated tearing,Z-direction steel was suggested. The position of the plastic hinge of the four specimens is inthe end section of the beam which is far away from the connection, and the position of theplastic hinge of the nomal specimen is80-130mm away from panel zone and is220mm forRBS specimen where the section was weaken the most; This kind of connection for weak axishas better ductility and high plastic rotational capacity. The ductility factor and plastic chordrotation angle of the7specimens all exceeded4and0.06rad respectively. There will be littleeffect on the bearing capacity of the specimen after the flange is weakened, and it can control the appearance position of the plastic hinge, which can further improve the ductility of thespecimen; Due to lack enough anchorage, the current design of fringe frame joint should nottake the effect of slab into consideration. For the8.2.8calculation of Code for seismic designof buildings has safety defect, it can not meet the "strong joint-weak levers" requirementswithout beam end processing to ensure the connection strength, and the use of higher gradeelectrode is advised. The main purpose for this paper is to consummate and supplement theI-section connection of weak axis, and the research contents of this paper can providereference for the follow study of this form connection.