Research On Mechanical Performance Of Slidable Joints In Existing Buildings And Elevators

In recent years,China has entered a society with an ageing population and the state has carried out nationwide renovation of old districts in order to speed up the urbanisation process and improve people’s living standards.Local governments have also actively introduced a series of policies to increase the transformation of old districts,of which the retrofitting of lifts in existing buildings is an important part of the transformation.The retrofitting of lifts to existing buildings in China has started late,and the research on quickfit steel lifts is not deep enough,so there are problems of structural safety,stability and connection with existing buildings in actual engineering cases.The nodal model proposed in this paper uses high strength bolts and long circular hole plates to connect the lift entry platform to the existing building,the aim is to reduce the deformation of the structure by dissipating energy through frictional slip between the bolts and the wall of the oblong hole and between the oblong hole plate and the spacer plate to resist seismic action.The reciprocating load,shear force-slip curve and bending moment-angle curve of nodes are theoretically deduced through design dimensions and numerical operations.Then,in order to obtain realistic performance data for the new slidable node and the conventional node,two components were designed for the experiment: the new slidable node QM1 and the conventional node QM2,the experiments were carried out by horizontal loading,using MTS for reciprocal displacement loading,the displacement and strain of the beam end are obtained through the displacement meter and static strain gauge,and the hysteresis curve,skeleton curve,stiffness degradation curve and energy dissipation curve of the component are obtained through analysis,and the ABAQUS finite element software is used to simulate the reciprocating load of the slidable node QM1,and compared with the curve obtained from the experiment.The results show that the new slidable node has the "pinch" feature,the shape of the hysteresis curve is full,the stiffness degradation is obvious,the energy dissipation performance is better than that of the traditional node,and the finite element simulation curve and the test curve basically coincide,which further verifies the test.To investigate the non-linear characteristics of the slipable node,one-way load simulations of the slipable node QM1 were carried out using ABAQUS finite element software to obtain the shear-slip and moment-turn simulation curves of the QM1 node.The effects of different bolt preloads and different friction coefficients on the two curves were also analysed,followed by equation fitting of the shear-slip and moment-turn angle curves using MATLAB software.The following conclusions are drawn: under the influence of bolt pre-tightening force and friction coefficient,the component generates a large static friction force,and the component slips only when the shear force on the component is greater than the maximum static friction force required for sliding.The shear-slip and moment-rotation curves both show semi-rigid characteristics,and the bolt preload and friction coefficient have a greater impact on the shear-slip curve and less on the moment-rotation curve.Through the MATLAB fitting curve,it can be seen that the exponential function has a better fitting effect than the polynomial function.Figure [90] table [14] reference [56]...