| The prefabricated buildings can significantly reduce the building energy loss,simplify the construction process and improve the recycling rate of components,which is an important technological path to fulfil the goal of “peak carbon dioxide emission and carbon neutrality” in the construction industry.The precast concrete(PC)shear wall structure is one of the most suitable structures for prefabricated concrete high-rise residential buildings because of its large lateral stiffness,high bearing capacity and regular indoor space.Compared with cast-in-situ(CIS)shear wall structure,the connection joints of the PC shear wall structure are the key factor affecting the mechanical performance of the structure system.The PC shear wall with wet connections can achieve the same seismic performance as the CIS shear wall,but a large number of on-site wet work will reduce the construction speed and lead to the difficult control of joint quality.The PC shear wall with dry connection is easy to construct and the installation quality is controllable,which can significantly improve the construction efficiency.Therefore,for the purpose of improving the seismic performance and construction benefit of PC shear wall,a new connection method featuring slip-friction connections(SFCs),applied in PC shear wall,was proposed in this thesis.The seismic behavior of PC shear wall with SFCs were systematically investigated through the quasi-static tests,numerical simulation and theoretical analysis.The main contents and conclusions are as follows:(1)The cooperative working mechanism of shear wall,SFC and steel column is expounded.And the sliding-locking mechanism of shear walls is theoretically analyzed with the friction force and sliding limit value of SFCs as the key factors.Finally,the design and numerical simulation of PC shear walls with SFCs are carried out based on ordinary shear wall.The results showed that the elastic stiffness of shear walls with SFCs is increased compared with that of ordinary shear walls,and the degree of increase is related to the elastic stiffness ratio of steel column and wall.The locking point of the SFCs obtained from the theoretical calculation is close to the simulation results,indicating that the proposed method of calculating the locking point of the SFCs is reliable.(2)Five PC shear wall specimens were designed and subjected to the quasi-static tests.The effects of the sliding distance,the number and the friction force of SFCs on the seismic performance of the PC shear walls were analyzed.Meanwhile,the test results were compared with those of CIS shear wall specimen.Test results indicated that it is feasible to use SFCs to connect PC shear walls,and the expected working mechanism of the PC shear walls is effectively achieved.The failure modes of the PC shear walls with long-hole and short-hole SFCs were web crushing and shear failure,respectively.Compared with the CIS shear wall specimen,the hysteresis curves of the PC shear walls are full,with higher energy dissipation capacity,higher bearing capacity,stable stiffness and strength degradation,ductility coefficients ranging from about 6.32 to 10.0.The PC shear walls with long-hole SFCs have better energy dissipation capacity and ductility,while the PC shear wall with short-hole SFCs has higher bearing capacity and later stiffness.The friction force and number of SFCs has little effect on the bearing capacity and ductility of the PC shear walls.(3)A numerical simulation method for PC shear walls with SFCs is proposed,and the effects of the axial load ratio,the stiffness ratio of the steel column to the wall,the sliding distance,the friction force and the number of SFCs on the seismic performance of the PC shear wall are investigated.The results showed that the proposed numerical simulation method can better describe the mechanical behavior of the PC shear wall.Increasing the axial load ratio can significantly improve the carrying capacity of the PC shear wall,but has less effect on the energy dissipation capacity and initial stiffness.Increasing the stiffness ratio of steel column and wall can effectively improve the bearing capacity and initial stiffness of PC shear wall,but has little effect on energy dissipation capacity and stiffness degradation,and it is recommended that the stiffness ratio of steel column to wall be 1.0～1.5.Increasing the friction force of SFCs can significantly improve the energy dissipation capacity of PC shear wall,but has no effect the bearing capacity and initial stiffness.Increasing the number of SFCs can significantly improve the bearing capacity,energy dissipation capacity of PC shear wall,and the recommended number is 4-6.Too small sliding distance of SFCs will lead to unexpected shear failure of the shear wall.Too large sliding distance of SFCs will delay the improvement of the bearing capacity and stiffness of the shear wall,it is suggested that the sliding distance is between 15 and 35 mm.(4)Based on the test results of the PC shear walls with SFCs,a simplified six-linear model was presented,which could reflect six key feature points of the skeleton curve,such as cracking point,yield point,primary peak point,locking point,secondary peak point and ultimate point.Then,a hysteretic rule was summarized to simulate the strength degradation,stiffness degradation,strength decay,pinch effect and SFCs locking characteristics of the hysteresis curve.Finally,a simplified six-linear restoring force model was established and verified by comparing the energy dissipation capacity and envelope curve.It was concluded that the simplified six-linear restoring force model agreed well with the hysteresis curves of PC shear walls with SFCs.(5)Two PC coupled shear wall specimens with friction-based coupling beam(FCB)and yielding-based coupling beam(YCB)were constructed and tested under quasi-static cyclic loading.The results showed that both PC coupled shear walls exhibit the same damage characteristics of the coupling beam yielding first and the shear wall yielding later,and achieve the seismic design objective of multi-pass protection.The hysteresis curves of the PC coupled shear wall with FBC are full,with good energy dissipation and deformation capacity,and the ductility coefficient of 8.4.While the PC coupled shear wall with YBC have higher load-bearing capacity.In addition,the FCB exhibits stable hysteresis performance and low damage characteristics,while the YBC has significant overstrength characteristics,which is unfavorable to the design of peripheral connection members.(6)A numerical simulation method for PC coupled shear walls with SFCs is proposed,and the effects of axial load,concrete strength,yield strength of the coupling beam and friction force of SFCs on the seismic performance of the PC coupled shear walls were further investigated.The results showed that the proposed numerical models can effectively simulate the mechanical behavior of the PC coupled shear walls;The coupling ratio of the PC coupled shear walls with FBC shows a trend of decreasing and then leveling off with the increase of loading displacement,while the coupling ratio of the PC coupled shear wall with YBC shows a trend of decreasing and then increasing with the increase of loading displacement.With the increase of axial load,yielding force of coupling beam and friction force of SFCs,the bearing capacity of PC coupled shear walls gradually increases,but the excessive axial load and friction force of SFCs will reduce the ductility of PC coupled shear walls.The concrete strength has less influence on the bearing capacity and deformation capacity of PC coupled shear walls.(7)A simplified analysis model of the PC coupled shear wall is established on the basis of tests and numerical simulations,and the calculation method of elastic stiffness and horizontal bearing capacity is proposed.The results showed that the theoretical value of elastic stiffness is larger than the experimental value,and the theoretical value of bearing capacity is conservative compared with the experimental value.In general,it can provide theoretical basis for further research of the PC coupled shear walls with SFCs. |
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