| Ductile and dissipative connections are recognized as their excellent seismic performance in engineering all over the world,which includes two types,that are reduced connection and reinforce connections.Compared with ordinary connections,it's obvious character is that plastic hinge keep away connection area of beam and column,which protect connection and structure,avoid whole damage under strong earthquake and improve life cycle of the structure.It is inevitable to analyze and check the structure when the ductile and dissipative connections are used in structure,however,construction of ductile connections is more complicated than that of ordinary connection,if structural entity models are calculated by finite element method,it will be feasible,but it is time-consuming.To improve the computational efficiency,in this paper the simplified models of ductile connections to simplify frame structure with the ductile connections are used,and simplified models of the frame are obtained,then internal force,deformation analysis and modal analysis are carried out.To seek rational simplified models of connections,in this paper three types of simplified model of connection are used to simplify the frame structure and the numerical results of the three frame structure models are compared,then the advantages,disadvantages and applicability of several simplified models of connections are analyzed.The main contents and conclusions of this paper are as follows:(1)First of all,according to relevant design specifications,3-layer and 6-layer steel frame with three different forms of connections are designed,and corresponding reduced beam section connection,cover-plate reinforced connection and widen flange section connection are also designed.(2)To obtain more reasonable simplified models of steel frames,frame structures are simplified by introducing three types of ductile connections with spring elements,based on the theoretical derivation of the connection spring element,solid models of exterior column element and interior column element are built by finite element method,the solid models of connection are carried out finite-element numerical calculation when one-way loading are applied at the end of the beam,constitutive relation of connections are obtained,then force-displacement curves of the spring elements are further extracted on the basis of the theoretical equation of the spring stiffness,to reflect the stiffness of the spring element and provide stiffness of connection for subsequentsimplified frame structure.(3)Three types of simplified frame models of three-layer and six-layer frame structures are built respectively by using three types of ductile connections,internal force and deformation of the simplified model of eighteen frames are carried out under three types of conditions.To reflect the reliability of calculation results,at the same time,actual models of steel structures are built and carried out numerical calculation under same conditions.Maximal bending moment of every layer and lateral displacement of top layer of six frame actual models and eighteen frame simplified models are compared with each other,it can judge whether it is feasible that static calculation of the frame are analyzed using the three types of simplification models of ductile connection.(4)To further expand and analyze whether it is feasible that simplified models of ductile connections are used in simplified steel frame.Eighteen types of simplified models of steel frames and six types of frame actual models are carried out modal analysis.Compared with fundamental period and modes of vibration of all steel frames,reliability of the simplified models of various ductile connections is further analyzed.(5)The results show that it is feasible to carry out static analysis and modal analysis in frames with ductile connections by using simplified models of ductile connections,which all obtain reliable calculation results comparing actual models of the steel frames. |
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