Study On Seismic Performance Of Prefabricated Steel Frame-damped Enclosure Wall Structure

A novel damped enclosure wall(DEW),considering the setting of door opening or(and)window opening,is proposed to solve seismic problems in prefabricated steel frame structure including earthquake-prone enclosure wall system(i.e.partition wall with door opening or(and)window opening),and adverse seismic influences caused by added stiffness and constraints from enclosure wall.And then,DEW is applied to the formation of prefabricated steel frame-damped enclosure wall structure system.Five specimens were designed and made for pseudo-static tests,and research was conducted on the energy dissipation mechanism of the DEW,the effect of protection for DEW and its opening.At the same time,the finite analysis of prefabricated steel frame-damped enclosure wall structure with different parameters is carried out.At last,combining with experimental research and finite element analysis,an equivalent mechanical model is established,which is suitable for the DEW with "wall-column" connection.The main research contents and conclusions are as follows:(1)Five specimens,including a prefabricated steel frame(PSF),a prefabricated steel frame-common enclosure wall with door opening(PSF-CEWD),a prefabricated steel frame-common enclosure wall with window opening(PSF-CEWW),a prefabricated steel frame-damped enclosure wall with door opening(PSF-DEWD)and a prefabricated steel frame-damped enclosure wall with window opening(PSF-DEWW),are designed and fabricated for low-cycle reciprocating tests.The experimental results show that: the common enclosure walls(CEW)of PSF-CEWD and PSF-CEWW provide excessive constraints and added stiffness,and the CEW are seriously damaged,and the fracture and deformation of door or window openings are obvious;the DEW of PSF-DEWD and PSF-DEWW realize friction slip-energy dissipation mechanism,effectively release the excessive constraints and added stiffness of the enclosure walls and improve the energy dissipation capacity of the frame;the DEW are intact,the openings do not deform,and the"wall-beam"connection is reasonable and reliable.(2)The PSF and PSF-DEWD are simulated by ABAQUS software,and the test results are in good agreement with the simulation results.In order to provide theoretical basis for the design of the DEW,twenty finite element models of prefabricated steel frame-damped enclosure wall(PSF-DEW)are established by ABAQUS software.The effects and rules of the height ratio of wall panels,friction coefficient of damping layer,wall panel material on the seismic performance of PSF-DEW and height of lintel,type of opening,door opening location,window opening dimension on the performance of the DEW are studied.The results show that: the seismic performance of the frame is improved with the increase of the height ratio of wall panels or friction coefficient of damping layer or wall panel density.In practical application,according to the design size of doors and windows,the height ratio of wall panels is selected as large as possible;when it is necessary to set window opening,it is recommended to set the window opening on the upper wall panel.At the same time,it is suggested that the material with higher friction coefficient be selected to make the damping layer and the wall panel with higher material density be selected.The change of lintel height or the window size has little effect on the stress of the DEW;when the door is biased,the tensile stress and compressive stress of the wall panel will increase,and the damage risk of the wall panel will increase.In practical application,it is suggested to set the door opening in the center.If the door opening needs to be biased,try not to arrange the door opening on the edge of the wall panel and the long-side wall should be added with T-type connectors.The change of lintel height or type of opening or position of the door opening or the window size has little effect on the horizontal deformation of the opening.The deflection of lintel is mainly affected by the height of lintel and the width of opening.The deflection of the lintel increases with the decrease of the height of lintel.It is suggested that the height of lintel should not be less than 150 mm.With the increase of the width of the window opening,the deflection of the lintel increases correspondingly.It is suggested to take reinforcement measures for the lintel when the width of the window opening is not less than 1000 mm.(3)The construction of PSF-DEWD and PSF-DEWW is introduced,and the interaction mechanism of the damped enclosure wall frame,and the energy dissipation mechanism of the DEW are revealed.Based on the equivalent mechanical model-DS model proposed by the research group for the damping wall with "wall-column" connection,a DS model suitable for the DEW with "wall-beam" connection is proposed,that is,two inclined bars with elasto-plastic spring units are used to represent the added stiffness and added energy dissipation of the DEW to the frame.The equivalent mechanical model of PSF-DEWD is established by ABAQUS software,and the analysis results are in good agreement with the test results and the corresponding simulation results,indicating that it is reasonable and feasible to adopt DS model to replace the DEW.