| As one of the common disasters,fire causes great damage to the building structure.In recent years,composite shear wall has been widely used in domestic projects due to its advantages of strong overall performance of cast-in-place concrete components and high industrialization of prefabricated components.However,there is little research on the mechanical performance of composite shear wall under and after high temperature.The research group has studied the seismic performance of composite shear walls filled with demolished concrete lumps(DCLs)and self-compacting concrete(SCC)at normal temperature.In this paper,from the perspective of disaster prevention and mitigation,the fire resistance performance and post fire seismic performance of composite shear walls filled with DCLs and SCC are studied and analyzed.The main work and conclusions of this paper are as follows:1.In this paper,three composite shear walls infilling DCLs and SCC are tested under double-sided fire.The effects of the fire retardant coating and the ratio of wall width-depth on fire resistance of composite shear walls infilling DCLs and SCC are revealed under constant axial compression ratio.The results show that:(1)The concrete temperature trend of the three specimens in the wall section is almost the same.Spraying fire retardant coating on the concealed column has a significant effect on the section temperature of steel tube column,while increasing the ratio of wall width-depth has little effect on the section temperature of steel tube column.(2)When the axial compression ratio is 0.19,the three specimens are in the expansion stage within 180 minutes,and there is no compression phenomenon.The results show that the expansion deformation of shear wall sprayed with fire retardant coating on the outer surface of concealed column steel pipe is smaller than that without fire retardant coating,and the axial deformation of composite shear wall infilling DCLs and SCC is not affected by increasing the ratio of wall width-depth.(3)The three specimens can bear the predetermined axial load stably within 180 minutes,meet the requirements of the first grade fire resistance rating,and have good fire resistance performance.2.ABAQUS finite element software is used to simulate the fire test of composite shear walls infilling DCLs and SCC.The effects of fire type,axial compression ratio and vertical reinforcement diameter of precast wall panel on the fire resistance of composite shear walls infilling DCLs and SCC are analyzed.The results show that:(1)The temperature field and axial deformation calculated by the finite element method are in good agreement with the experimental results,which indicates that the finite element model established in this paper can be used to simulate the fire resistance of this kind of components.(2)With the increase of the number of fire surface,the fire resistance of composite shear walls infilling DCLs and SCC decreases.(3)The axial compression ratio has no obvious effect on the fire resistance of the single-sided specimens,while the fire resistance of the double-sided specimens and the four sided specimens decreases with the increase of the axial compression ratio.(4)The change of steel bar diameter has no obvious effect on the fire resistance of single side fire specimen,but the fire resistance of double side fire specimen and four side fire specimen increases slightly with the increase of vertical steel bar diameter.3.The quasi-static tests of four composite shear walls infilling DCLs and SCC were carried out to reveal the effects of fire time,the fire retardant coating and the ratio of wall width-depth on the seismic performance of composite shear walls infilling DCLs and SCC after fire.The results show that:(1)The failure displacement angles of the four shear walls meet the requirements of the code,and the ductility coefficients are large,indicating that they have good deformation capacity.(2)The horizontal bearing capacity,deformation capacity,initial stiffness and energy dissipation capacity of the composite shear wall infilling DCLs and SCC after 60 minutes of fire are lower than those of the specimen without fire,but the decrease is small,which indicates that the composite shear wall infilling DCLs and SCC still has good seismic performance after 60 minutes of fire.(3)The fire retardant coating on the outer surface of the concealed column steel tube has limited influence on the seismic performance of the specimen after fire.(4)The results show that increasing the ratio of wall width-depth can obviously improve the horizontal bearing capacity of shear wall after fire,and the initial stiffness,stiffness degradation and energy dissipation capacity also have different degrees of improvement,but the deformation capacity becomes weak,which indicates that increasing the ratio of wall width-depth has a significant impact on the seismic performance after fire. |
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