| At present,the country is vigorously promoting the prefabricated building,and the development of prefabricated building is the only way for the construction industry to improve the level of industrialization and improve production efficiency.The so-called prefabricated building is the beam,plate,column and other structural components processed in the factory,and then transport to the site for assembly,which can greatly speed up the construction speed,reduce the amount of template,save labor.Because the composite plate has good integrity,construction is convenient,mechanical performance is good wait for an advantage,thus becoming the mainstream of the prefabricated building floor system,in this context we put forward the concept of grid composite slab.The so-called grid composite slab is to pull part of the concrete tension area,leaving only a width of 50 mm rib,so that the steel in the rib through.At the same time,in order to ensure the smoothness of floor bottom,we use the foam cement block to replace the concrete part.Foamed cement block is a kind of thermal insulation material,which has good thermal insulation and sound insulation effect.Therefore,coMPared with solid board,grid composite slab not only significantly reduces its dead weight,but also has better thermal insulation and sound insulation effect.Due to the hollowing out of the concrete in part of the tension zone,the dead weight of thegrid composite slab is reduced by about 30.8%.However,while the dead weight is reduced,the mechanical performance of the grid composite slab greatly improved.Through the previous tests of our research group,it was found that the bearing capacity of the grid composite slab could be improved by 23.08%.However,there are still some places to be improved in the grid composite slab,such as the small cracking load of thegrid composite slab,the low stiffness in the early stage and the excessive deformation.We hope that by applying prestress to increase the cracking load and stiffness of the grid composite slab,however,there are few related literatures on the mechanical properties of prestressed slab composite slabs,so we hope to obtain the data about the mechanical performance of the prestressed slab composite plate through the static load test.It provides guidance for the future application of prestressed grid composite slab in practical engineering.The specific research contents of this paper include:1.Simulate the construction process of prestressed grid composite slab.After the first phase of concrete pouring is completed for 28 d,the precast slab will be removed,and then the prefabricated slab will be hoisted onto the simple support,and the precast slab will be set up and poured.In order to observe the hoisting performance of the prestressed grid laminated plate and the stress situation in the construction process of the post-pouring layer.2.Study the anti-arch characteristics of composite plates after applying prestress,and provide guidance for anti-arch calculation.3.In the stage of failure test,the cracking load,crack development law,deflection,stress distribution characteristics of reinforcement and concrete,and ultimate bearing capacity of prestressed grid composite slab are mainly studied,and the cracking load,ultimate load and deflection are given.4.The application of prestress may have a certain iMPact on the shear strength of the composite surface.Therefore,one aspect of the experimental research lies in the cooperative work between the precast slab and the composite layer,that is,whether the old and new concrete will generate relative slip under stress.5.This paper studies whether the cement block and concrete can be bonded firmly to prevent the slabs from falling off during the later use of prestressed grid composite slab.6.The improvement of stiffness,crack and bearing capacity by applying prestress is studied by coMParing with the experimental data of prestressed grid slab.7.Finite element software ABAQUS was used for numerical simulation to verify and supplement the test results. |
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