| The use of prestressed concrete walls is a structural measure to prevent unwanted tensile-shear failure of shear walls in high-rise buildings under earthquake actions.This thesis investigates the seismic behavior of bonded prestressed concrete walls,validates the formulas used to calculate the flexural and shear strength of the walls,and compares their seismic behavior with steel-reinforced concrete（SRC）walls.The main work and results are as follows:（1）Quasi-static tests of three prestressed concrete wall specimens and one SRC wall specimen with a high aspect ratioλ=2 were conducted.The failure modes and seismic behavior were investigated for the wall specimens subjected to constant or varied axial forces and cyclic lateral loading.The tests indicate that the lateral strength of slender prestressed concrete wall specimen was 10%lower than that of the SRC specimen,while the lateral stiffness and stiffness degradation of the former were nearly identical to those of the latter.The prestressed concrete wall specimen has narrower cracks than the SRC wall specimen.The prestressed concrete specimens under the constant axial tensile force(the average nominal tensile stress of concreteσt=3 ftk,whereft kdenotes the nominal tensile strain of concrete)or under the constant axial compressive force（the design axial compressive force ratio dn=0.75）had an ultimate drift ratio of 3.7%or 1.8%,and the prestressed concrete specimen under varied axial forces had an ultimate drift ratio of 2.3%,all exceeding the drift limit of 1/100 as specified in the Chinese design code.The slender prestressed concrete wall specimens under constant axial forces failed primarily in shear mode,while the specimen under varied axial forces failed primarily in flexural mode.The variation in axial tensile-compressive forces led to 6.2%and 23.0%decrease in the tensile-flexural strength and compression-flexural strength,respectively.The variation in axial forces also led to the decrease of tensile-flexural deformation capacity of the slender prestressed concrete wall specimen by 33.8%.（2）Quasi-static tests of three prestressed concrete wall specimens and one SRC wall specimen with a low aspect ratioλ=1 were conducted.The failure modes and seismic behavior were investigated for the wall specimens subjected to constant or varied axial forces and cyclic lateral loading.The tests indicate that the lateral strength of the squat prestressed concrete wall specimen was 12.3%lower than that of the SRC wall specimen,while the lateral stiffness and stiffness degradation of the former were similar as those of the latter.The crack width of the prestressed concrete walls was smaller than that of the SRC wall.The prestressed concrete wall specimens under the constant axial tensile force（σt=3 ft k）or the constant compressive force（dn=0.75）had an ultimate drift ratio of1.6%or 0.6%,and the specimen under varied axial forces had an ultimate drift ratio of1.2%.The squat prestressed concrete wall specimen with a constant axial tensile force failed in shear mode,while the specimen with a constant compressive force failed in diagonal compression mode because the shear force exceeded the web crushing limit.The prestressed concrete wall specimen under varied axial forces failed in shear-compression mode.The variation of axial tensile-compressive forces led to 18.7%and 10.5%decrease in the tensile-shear strength and compressive-shear strength,respectively.The variation of axial force also led to the decrease of tensile-shear deformation capacity of the squat prestressed wall specimen by 24.9%.（3）The strength of the specimens calculated as per Chinese design formulas were compared with the test results.The experimental-to-calculated ratio for the tensile-flexural strength and compressive-flexural strength of the slender prestressed concrete wall specimens were 1.25 and 1.13,respectively.The average values of experimental-to-calculated ratio for the tensile-shear strength and compressive-shear strength of the squat prestressed concrete wall specimens were 2.39 and 1.99,respectively.Therefore,the design formulas can provide a reasonable and conservative estimate of the strength capacity of prestressed concrete walls. |
