| In recent years,high-strength steel structures have been used in actual projects at home and abroad due to their high strength and good mechanical properties.However,the properties of high-strength steels are different from ordinary steels,so research on the performance of high-strength steel structures is particularly urgent.Fracture is one of the two important failure modes of steel structure.At present,research on the fracture properties of high-strength steel structures has important engineering value and social significance.Based on combing the development history and research status of high-strength steel connections and micromechanical fracture model,the fracture performance of Q460 high-strength steel beam-column welded connections with different welding hole forms was studied by experiments and micromechanical fracture model in this paper.The main work contents and research results of this paper are shown below:(1)Pseudo static tests were performed on three Q460 high-strength steel beam-column welded connections with three different welding hole forms.The results show that Q460high-strength steel beam-column welded connections with three different welding hole forms all have good energy dissipation capacity and ductility.Among them,the connection form corresponding to the welding hole recommended by the US code FEMA350 shows the best ductility but lower strength.The conventional connection recommended in the technical specification for steel structure of tall building has slightly worse ductility but higher bearing capacity.It shows that the form of welded holes has a certain effect on the fracture performance of welded connections of steel beams and columns.Although the expansion of welded holes will reduce the bearing capacity of the connections,the ductility of the connections can be improved,which is good for earthquake resistance to a certain extent.The method of appropriately expanding the welding hole can be used for the connections with high seismic performance requirements and sufficient strength.(2)The Cyclic Void Growth Model(CVGM)combined with ABAQUS finite element simulation was used to predict the fracture of Q460 high-strength steel beam-column welded connections.The results show that the fracture prediction results in terms of fracture load,fracture displacement,fracture moment and fracture position are basically consistent with the test results.The CVGM model is reliable for the fracture prediction results of Q460high-strength steel beam-column welded connections.(3)The CVGM model was used to predict the fracture of 7 self-designed locally no welded hole connections in the steel structure,and the fracture performance results of each specimen were compared and analyzed.The results show that:(1)The use of locally no welded hole connections can effectively prevent cracking of the base metal near the upper flange welds of the beam,and the connection cracks mostly occur at the lower flange base metal near the welded holes.Although locally no welded hole has a less significant effect on improving bearing capacity of the connection,it has a certain effect on delaying the fracture initiation of the connection.(2)Increasing the length,height,or radius of the traditional welded hole almostly has no effect on the fracture initiation position of the locally no welded hole connections with the form of traditional welded holes,and it has little effect on the ultimate bearing capacity before fracture initiation of the connections.Properly increasing the length or radius of the welding hole can effectively delay the fracture initiation of the locally no welded hole connection and improve the ductility of the connection,but increasing the height of the welding hole will make the fracture initiation of the locally no welded hole connection occur in advance and the ductility be slightly reduced. |
PDF Full Text Request