| In recent years,in response to the call of the national low-carbon life,energy conservation and emission reduction and green building policies,various places have begun to vigorously promote prefabricated buildings.For Xinjiang and other places in high intensity cold areas,the development of prefabricated buildings should focus on structural insulation integration,"sandwich" sandwich shear wall is a typical form of structural insulation integration technology application.As the country has successively issued building energy-saving policies,the future prefabricated low-energy buildings are an important development direction,and the further improvement of the energy saving rate is bound to bring about an increase in the thickness of the insulation layer of the enclosure wall,and there is a trend of exceeding the limit of the thickness of the insulation layer of the specification.Therefore,focusing on the potential problems in the development of prefabricated buildings in Xinjiang region,this paper designs and produces 1 cast-in-place sandwich shear wall and 5 prefabricated sandwich shear walls.Based on the test and theoretical analysis,the failure forms,mechanical properties,co-working performance of the inner and outer blade walls and the design of new connectors with larger insulation layer are studied.The main work and conclusions are as follows:(1)One cast-in-place sandwich shear wall and three assembled sandwich shear walls are subjected to monotone loading tests.The results show that: The development trend of cracks of cast-in-place specimens is basically the same as that of assembled specimens,and the bearing capacity is basically the same,which verifies the effectiveness of sleeve grouting connection.However,the difference in cracking load is large,because the assembled specimens have weak surface at the bottom of the grouting layer,and the bonding between the grouting material and the wall is poor.Because the bearing capacity of the wall is mainly borne by the steel bar and concrete of the inner blade wall,different insulation thickness and different connection forms have little influence on its bearing capacity.When the wall is damaged,the outer blade wall is still closely connected with the inner blade wall through the connecting pieces,and the outer blade wall is codeformed with the inner blade wall,and there are no visible cracks on the surface.Under this failure mode,the outer blade wall has a low degree of participation in the structural force.(2)The low-cycle reciprocating loading tests were carried out on different typical walls,and the results showed that the failure mode of the test pieces of the window holes was shear failure,and the failure mode of the test pieces of the door openings was bending failure.The horizontal relative displacement of the inner and outer leaf walls of the two specimens began to occur after the cracking of the specimens,and reached the peak value when the specimens reached the yield,with the horizontal relative displacement of 3.12 mm.When the specimens reached the failure state from the yield state,the horizontal relative displacement basically no longer changed.Due to the constraint effect of the lower window wall on the edge members,the internal stress of the specimen is redistributed,and the bearing capacity and initial stiffness of the specimen are increased by 30.8% and 37%,respectively,compared with that of the door entrance.The ductility coefficients are 1.88 and 2.14,respectively.While the structural stiffness of the lower window wall is increased,the ductility ability of the structure is decreased.The stiffness and height of the wall under the window determine its constraint on the edge members.A formula is proposed to judge the shear failure of the wall column by the ratio of the stiffness of the constrained section and the stiffness of the free section under the window wall.(3)According to the current specifications,the design and calculation method of metal insulation connectors is given.Vertical shear tests are carried out through two prefabricated sandwich shear wall connectors with larger insulation layers.The research results show that: The final failure of the specimens was due to the failure of the anchor end of the local connector,resulting in the overall instability failure.The ultimate bearing capacity of a single FRP root was 11.45 k N,and the maximum vertical displacement was7.0mm;the ultimate bearing capacity of a single metal insulation connector was 28.86 k N,and the maximum vertical displacement was 7.8mm.Metal insulation connectors have higher strength and deformation capacity than FRP connectors.The test value of the shear strength of FRP connectors and metal insulation connectors is much higher than the design value,and has a large safety reserve.According to the final failure mode of the test,the optimization suggestions for the connectors are put forward to reduce the project cost. |
