| The assembled monolithic concrete superposed shear wall structure is connected using the additional connecting reinforcements in the cavity layer as a whole by the cast-in-place concrete in the cavity layer and the superposed precast concrete panels which are connected by reinforcement trusses.The structure has the advantages of light weight of precast wall panels with cavity layer,high efficiency for transportation,good structural integrity after assembly construction,good waterproof efficiency of joints,and can be produced with insulation in the factory,which has is a considerable promise for application.Most of China is in the earthquake prone area,so whether assembled monolithic concrete superposed shear walls can be used in high seismic intensity areas,and whether they can be used in high-rise or even super high-rise buildings has become an urgent issue.The assembled monolithic T-shaped and L-shaped concrete superposed shear walls consist of precast superposed flange panels,superposed web panels,boundary elements and cast-in-place concrete in the cavity layer connected by additional horizontal connecting reinforcements in the cavity layer.The axial compressive load ratio,boundary elements,and the connection way of horizontal and vertical joints are the main factors affecting the seismic performance of assembled monolithic T-shaped and L-shaped concrete superposed shear walls.Based on the connecting way between the cast-in-place concrete and the precaste concrete wall panels by setting additional horizontal connection reinforcement in the cavity layer recommended by the current national standard GB/T 51231-2016,a new precaste concrete wall panels connected by circle reinforcement connection was proposed.Meanwhile,a new construction of single-sided superposed concrete shear wall panels with high insulation efficiency has been provided for the function demand of the integration of structural-insulation.Through the quasi-static cyclic loading test,the seismic performance and main influencing factors of assembled monolithic T-shaped and L-shaped concrete double-sided superposed shear walls,single-sided superposed shear walls and cast-in-place shear walls were compared and analyzed.Combined with the results of finite element numerical simulation and theoretical analysis,the sectional calculation methods and structural recommendations for assembled monolithic T-shaped and L-shaped concrete superposed shear walls are proposed,and it provide a reliable experimental and theoretical basis for further improving the design methods and related engineering application technologies of the assembled concrete structural system.The main work and innovative achievements of this paper are as follows.(1)The quasi-static cyclic loading test of six assembled monolithic T-shaped and L-sharped concrete superposed shear wall full-scale specimens with boundary columns and two cast-in-place shear wall full-scale comparisve specimens were completed.The test results show that T-shaped and L-shaped concrete superposed shear walls with boundary columns and axial compressive ratio of 0.2 and shear span ratio of 1.5 exhibit typical flexural and shear failure,which is characterized by concrete collapse at the bottom of one side of web end and steel buckling under compression.When the flange is under tension,the bearing capacity of T-shaped double-sided superposed shear wall is reduced by 11.6% and that of L-shaped superposed shear wall is reduced by 6.5% at least compared with that of cast-in-place shear wall.When the flange is under compression,the vertical lapped connecting steel bars in the tension zone fully worked.When the concrete in the compression zone is not crushed,the internal force distribution of the flexural section of the horizontal joint is basically the same as that of the cast-in-place specimen,and the bearing capacity of both is basically similar.(2)Compared with cast-in-place shear wall,the maximum bearing capacity of T-shaped single-faced concrete superposed shear wall with boundary columns is increased by 10.6%,the ductility and energy dissipation capacity are slightly lower,and the stiffness degradation characteristics are similar.The maximum ultimate bearing capacity of T-shaped single superimposed shear wall is 22.8% higher than that of T-shaped double-faced superposed shear wall,and the maximum displacement ductility coefficient is 31.0% and 34.2% lower than that of T-shaped double-faced superposed shear wall.The bearing capacity of L-shaped single-faced composite shear wall with boundary columns is close to that of double-faced composite shear wall,and the displacement ductility coefficient under flange tension is 7.4% lower than that of L-shaped double-faced concrete superposed shear wall.The bearing capacity of integrated concrete superposed shear wall structure can be enhanced by adopting single superposed shear wall with concrete thickness not less than 150 mm after the casting of the middle cavity layer in the outer wall.(3)The quasi-static cyclic loading test of eight assembled monolithic T-shaped and L-sharped concrete superposed shear wall full-scale specimens with special boundary elements and two cast-in-place shear wall full-scale comparisve specimens were completed.The test results show that the T-shaped concrete superposed shear walls with special boundary elements and axial compressive ratio of 0.4 and shear span ratio of 1.5 are mainly characterized by flexural-shear failure,and shear slip of main inclined cracks also occurs.Compared with the cast-in-place specimens,the maximum peak bearing capacity and displacement ductility coefficients of T-shaped concrete concrete superposed shear wall are increased by 7.4% and 43.4%respectively.The peak bearing capacity of L-shaped concrete superposed shear wall is19.4% higher than that of the cast-in-place specimens,and the displacement ductility coefficient is 58.5% higher than that of the cast-in-place shear wall.(4)The peak bearing capacity,ductility,stiffness degradation and energy dissipation capacity of the T-shaped single-faced concrete superposed shear wall with special boundary elements are basically the same as those of the T-shaped double-faced concrete superposed shear wall.The peak bearing capacity of L-shaped single-faced composite shear wall with special boundary elements is basically similar to that of the L-shaped double-faced concrete superposed shear wall.Compared with the L-shaped double-faced concrete superposed shear wall,the displacement ductility coefficients increase by a maximum of 13.6% and 25% when the flange is under tension and compression.The stiffness degradation characteristics and energy dissipation capacity are similar.(5)The spacing with 400 mm of FRP connectors of T-shaped and L-shaped single-faced concrete superposed shear wall can realize reliable connection among the thermal insulation layer,outer leaves precast wall panel and cavity after the pouring of concrete layer and inner panel.The T-shaped and L-shaped single-faced superposed shear wall outside panel is the structure with little force,and the outside panel and deformation of the part of structure has good ability of coordination.In practical engineering design,it is recommended to adopt T-shaped and L-shaped single-faced superposed shear walls with special boundary elements in the form of non-equal length of outer precast panel.(6)The maximum bearing capacity of the T-shaped and L-shaped superposed shear walls is increased by 4.5% when the circular reinforcement connection proposed in this paper is adopted compared with that of the T-shaped and L-shaped superposed shear walls.The circular reinforcement connection can effectively reduce the cracking of vertical joint superposed layer,which can fully ensure the overall connecting of vertical joint of the T-shaped and L-shaped superposed shear walls.(7)The seismic performance of the assembled monolithic T-shaped and L-shaped concrete superposed shear wall specimens was reasonably modeled and computed using finite element analysis software,and the calculated results were in good agreement with the experimental results.The additional analysises of the influence of the calculation parameters such as axial compressive load ratio,shear-to-span ratio,flange height-to-width ratio,direction of seismic action on the seismic performance of the assembled monolithic T-shaped and L-shaped concrete superposed shear walls on the basis of the experimental parameters were done.(8)Based on the results of the series of seismic test and finite element calculation,the formulae for calculating the effective flange widths of T--shaped and L-shaped concrete superposed shear walls under two force conditions of flange in compression and in tension were derived using by regression analysis.The formulas are in good agreement with the results of the tests and the finite element calculations,and the error is less than 11%.(9)Based on the results of the series of seismic tests and finite element calculations,a static mechanical analysis model of assembled monolithic T-shaped and L-shaped concrete superposed shear walls under earthquake action is established considering the seismic adjustment coefficient of bearing capacity,and the formulas of compressive strength of the normal section and the shear strength of the inclined section under earthquake design condition are proposed.The comparison results show that the mechanical model and calculation formulas can reflect accurately the compressive-flexural force characteristics and failure mode of assembled monolithic T-shaped and L-shaped concrete superposed shear walls under the combined action of the horizontal and vertical loads,and the average error between the theoretical calculated and tested values of the compressive strength when the flange is in tension and in compression is 5.0% and 7.0% respectively,and the average error between the theoretical calculated and tested values of the shear strength is only 3%.Finally,the corresponding design suggestions are provided for the structural design of the assembled monolithic concrete superposed shear wall structures. |
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