The Study On Mechanical Behavior And Fracture Property Of Modified Connection Of Steel Frame

A large number of experimental studies and finite element analysis on reduced beamsection connection of steel frame showed that dog-bone connection and opening in beam webconnection can out moving plastic hinge effectively, and the beam flange welding root stressconcentration can also be relieved. Because the stress mechanism of above two reduced beamsection connections is different, so the destruction form of these connections is different.In this thesis, finite element analysis result and testing result of opening in beam webconnection is compared in order to verify the rationality of the finite element programparameters settings. On this basis, according to domestic and foreign stress mechanismresearch results of dog-bone connection and opening in beam web connection, and widenflange-dog bone connection suggested by standard atlas of “connection details in multi-storeyand high-rise steel structures”(01(04)SG519), base connection, dog-bone connection,opening in beam web connection and widen flange-dog bone connection are compared in thisarticle.Comparative analysis between three modified connections and base connection undermonotonic loading shows that the widen flange-dog bone connection have better mechanicalperformance than dog-bone connection and opening in beam web connection, it can reducedearly fracture probability in welding area due to bad welding quality. The stress in weldingaccess hole root area is larger than the center of top flange root area, the stress concentrationat welding access hole root area is more obvious. So it is suggest that use reasonable weldingaccess hole shape in order to reduce stress concentration at intersect of welding access holeroot and beam flange, and reduce possibility of tearing failure occurred.Comparative analysis between three modified connections and base connection undercyclic loading shows that the widen flange-dog bone connection have better deformabilitycapacity and energy dissipation capacity, and the accumulative damage index at beam flangeroot welding area is least, so it is worth promoting.Analysis on fracture property of opening in beam web connection shows that while thedistance between center of opening in beam web and Column flange is certain, The J-integralis increased with the hole diameter increased, and while the hole diameter is certain, Thedistance between center of opening in beam web and Column flange has less influence toJ-integral. In addition, The J-integral is increased with the beam weaken axis rotary radiusincreased, and the brittle fracture performance of square steel column connection is betterthan joist steel connection.