| In recent years,with the national promotion of prefabricated buildings,construction related industries began to actively promote the relevant technology research and development work.The structure of composite slabs is also developing continuously,among which the prestressed concrete steel pipe truss composite slabs are studied by scholars because of their superiority in performance.The composite plate eliminates the lower chord reinforcement of the truss reinforcement and replaces the upper chord reinforcement with grout steel pipe.The dead weight and reinforcement amount can be reduced,and the use of prestress can reduce the deflection deformation of composite plate.At the same time,the composite plate also overcomes the problems of the self-supporting reinforced truss concrete composite plate,such as large plate thickness,many supports,many plate joints and difficult pipeline crossing.At present,some large span laminated floor slabs used in the actual project,or a number of prefabricated one-way slabs in the field of splicing.In practical use,there will be problems such as unfirm joint,leaky joint and uneven force.To this end,this paper designs a one-way prestressed concrete steel pipe truss prefabricated bottom plate with plate thickness of 35 mm and a composite plate with plate thickness of 130 mm.The research is carried out from the following three aspects:(1)the bearing capacity,failure form and rebound deformation after failure of large span prefabricated bottom plate are studied;(2)Study the mechanical performance,internal force distribution and failure mode of non-spliced laminated floor;(3)Study the mechanical properties of non-splicing laminated floor slabs without transverse reinforcement in the laminated layer,and make a comparative analysis with the composite slabs with transverse reinforcement,so as to reduce the amount of steel used in the actual project.In this paper,the finite element software was used to determine the loading scheme,ensure the rationality of the test,and arrange the correlation measuring points according to the simulation results.In the test,the strain and deflection of concrete and steel tube truss under static load were investigated.Combined with load-strain curve,load-deflection curve and crack development diagram of composite plate,the test phenomena and results of prefabricated bottom plate and composite plate were described,and their mechanical properties under static load are analyzed.ABAQUS finite element analysis software was used to analyze the degree of fitting between the numerical simulation results and the test results.The parameter analysis was carried out by changing the configuration of reinforcement,the strength grade of concrete in the composite layer,the application of prestressed reinforcement,the diameter of transverse reinforcement and the thickness of composite plate.The results of test and finite element simulation show that the prefabricated floor still has good deformation performance and overall flexibility after reaching the ultimate load.According to the crack shape,load-displacement curve and load-reinforcement strain curve of unidirectional prestressed concrete steel pipe truss composite slab,the bidirectional force transfer performance of the composite slab is good,and the plastic strand during failure is basically consistent with the bidirectional slab.Although the stiffness in the non-prestressed direction is slightly lower than that in the prestressed direction,the bidirectional mechanical performance of the new plates is still very good.Based on the analysis of the influence of reinforcement configuration in the laminated floor,it is concluded that the use of transverse reinforcement and steel mesh in the laminated floor can be weakened without splice,so as to reasonably reduce the amount of reinforcement under the condition of normal use.In order to demonstrate the correctness of the test results,the finite element analysis is also carried out on the specimens for comparison,and it is found that they were basically consistent with the test results.It shows that the test results have repeatability and objectivity,which provides theoretical support and method for the better application of composite plate in engineering.Figure [72] Table [16] Reference [63]... |
