| It is one of the important measures for improving the quality of the construction engineering to develop the assembled buildings,and is also an important measure for the transformation and upgrading of the construction industry and the realization of the modernization of the construction industry.The precast concrete shear wall-frame structure is an important structural form of industrial buildings because of its remarkable advantages,such as flexible layout,wide application and rapid speed of construction,etc.In this dissertation a concept of new full precast shear wall-frame structures is proposed firstly,which is based on the common monolithic precast concrete shear wall-frame structure with monolithic cast-in-place shear walls,and then pseudo-static tests and numerical simulation are carried out to investigate the seismic behavior of the new structures.The main works and outcomes are as follows:(1)The splitting and assembly schemes of the beams,columns and joints in the existing monolithic precast concrete frame and shear-wall structures were studied.Based on the research results,two types of full precast concrete shear wall-frame structures were put forward,which are"full precast shear wall-frame structure with reinforcements splicing by grout-filled sleeves"and"full precast shear wall-frame structure with reinforcements lapping by U-shaped reinforcing bars".(2)In order to investigate the reliability and construction method of constraint grout-filled lap connection of steel bars,2 groups of 144 specimens were fabricated and tested.Half of them were tested under simple tensile loading,and the other half were tested under repeated tension-compression loading with high stresses in steel bars.The experimental parameters included bar diameter,lapping length,amount of stirrups and concrete strength.The test results indicated that the constraint grout-filled lap connection with steel bars is simple,convenient for real construction and the connection performance is reliable.(3)A new type of grout-filled sleeve with embedded codes was developed.The sleeve was machined with a low-alloyed standard seamless steel pipe.With two cones embedded in the two sides of the sleeve body,and then the sleeve body outside the end of the cones was extruded through cold rolling techniques,finally with many shearing bolts screwed in the sleeve body,which can improve the bond strength between the sleeve and inner grout as well as the sleeve and surrounding concrete.4 groups of 12 specimens were designed and tested through pullout test.The ultimate tension load,residual deformation and distribution of the bond stress along the bonded length were studied.A reversed cyclic lateral loading test was conducted on a precast concrete column to verify the connection reliability of the new grout-filled sleeves.The test results indicated that the new grout-filled sleeve is convenient,cheap and reliable.(4)The loading process of the precast concrete(PC)shear walls under pseudo-static tests was simulated using the finite element software ABAQUS.The simulation results agreed well with the experimental results.The simulation results showed that the bearing capacity of the PC shear walls decreased,and the ductility increased firstly and then decreased with the increase of the height-width ratio.The bearing capacity of the PC shear walls increased,however the ductility decreased with the increase of axial compression ratio.The bearing capacity increases with the increase of the reinforcement ratio of the PC shear-wall section,however the ductility coefficient of the wall increased decreased continuously.The bearing capacity of the PC shear walls increased with the increase of the concrete strength of the shear walls,however the growth rate slowed down,according to the simulation results some design suggestions were proposed.(5)Two PC and one cast-in-place specimens were designed and fabricated,and then conducted under pseudo-static tests,all specimens were half-scale two-story two-bay RC shear wall-frame structure specimens.One of the two PC specimens was a full precast one with prefabricated shear wall panels and prefabricated frames.The other was a semi-precast one with monolithic cast-in-place shear wall and prefabricated frames.Main longitudinal bars in both PC specimens were spliced by grout-filled sleeves.The seismic behaviors,including the failure mode,hysteretic response,stiffness degradation,displacement ductility and energy dissipation capacities,all these parameters of the full precast one were compared with the semi-precast one and the monolithic cast-in-place one.The test results showed that the full precast one had similar failure mode as the other two specimens,shorter length of plastic hinges,and the position of the plastic hinges were shifted out.The test results also showed that the full precast one has better energy dissipation capacity than the cast-in-place one,The seismic characteristic values such as yield load,peak load,and ultimate load of the full precast one was larger than those of the cast-in-place one.However,the displacement ductility was slightly less than that of his cast-in-place one,and the energy dissipation capacity of the full precast shear wall-frame structure grew more steadily during the whole loading process.It had good energy dissipation characteristics.According to the test results,some design suggestions were proposed.(6)Two PC specimens were designed and fabricated,and then conducted under pseudo-static tests,both specimens were half-scale two-story two-bay RC shear wall-frame structure specimens.One of the two PC specimens was a full precast one with prefabricated shear wall panels and prefabricated frames.The other was a semi-precast one with monolithic cast-in-place shear wall and prefabricated frames.Main longitudinal bars of the two PC specimens were lapped by U-shaped reinforcing steel bars.The indices of the seismic performance of the structure,such as the failure mode,hysteretic response,stiffness degradation,displacement ductility and energy dissipation capacities were analyzed comparatively.The test results showed that the full precast one had similar cracking load,failure process and ultimate failure mode as the other two specimens.The grout-filled sleeves,constraint grout-filled lap connection can effectively transfer the stress of the steel bar,and the full precast one had good integrity.The test results also showed that the full precast one has better energy dissipation capacity than the cast-in-place one.Seismic characteristic values such as yield load,peak load,and ultimate load of the full precast one were larger than that of the cast-in-place one.However,the displacement ductility was marginally less than that of the cast-in-place one,and the energy dissipation capacity of the full precast shear wall-frame structure was better than the cast-in-place one during the most loading process.Based on the test result,some design suggestions were proposed in the end.(7)The loading process of the two kinds of full precast shear wall-frame structures under pseudo-static tests was simulated using the finite element software ABAQUS.The simulation results agreed well with the experimental results.The FEA parametric analysis results showed that it would not significantly improve the bearing capacity of the structure though improving the concrete strength simplely;the spacing of the stirrup on the beam end has little effect on the macroscopic mechanical properties of the full precast concrete shear wall-frame structures.With the increase of the axial compression ratio(n_F/n_W),the bearing capacity of the full precast concrete shear wall-frame structure was increased,while the ductility decreased,and with the increase of axial compression ratio(n_F/n_W),the ultimate displacement of the specimen becomes smaller and smaller.Depending on the simulation results some design suggestions for the full precast shear wall-frame structures were proposed.(8)The calculation methods of the bending bearing capacity,the shear bearing capacity of the PC shear walls,the shear bearing capacity of the horizontal and vertical joints in the PC shear walls in the full precast shear-wall frame structures were studied.Based on the above research results of tests and finite element analysis,the design method of the new full precast shear-wall frame structures were put forword in the end,which would facilitate the extension and application of such structures in practical engineering. |
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