Study On Mechanical Properties Of Prestressed Laminated Bottom Plate Of Stell Tube Truss During Construction

As a result of promoting and developing prefab buildings nationwide,construction-related industries in recent years actively carry out technology research and development related to prefabricated buildings.Compared with traditional composite slabs,prestressed steel truss composite slabs with supports have greater bearing capacity,better stiffness and better seismic performance.Due to the higher and higher requirements for new composite boards in practical engineering,the industrialization of materials conforming to the architectural requirements has attracted the wide attention of many scholars.In this paper,three kinds of prestressed steel tube truss prefabricated bottom plate with widths of 2100 mm,2400mm and 3900 mm are designed and tested to simulate the construction condition.The following aspects are studied:(1)the bearing capacity and failure pattern of large span prefabricated bottom plate with support are studied;(2)Put forward the interim support plan of pre-stressed steel tube truss composite board base board through calculating formula;(3)Comparison between the results of FEM and experimental data,and the parameters were analyzed,and the effect of 5 factors on the performance of the specimen were analyzed: the height of girder,the intensity level of the base board,the thickness of the base board,the pre-stressed strengthening and the concrete in the tube.In this paper,the bearing capacity test of prestressed steel pipe truss prefabricated bottom plate with support is designed to simulate the variation of the strain of concrete,steel pipe and steel bar and the deflection of the bottom plate under static load in the construction stage.Based on load-strain curve,load-deflection curve and crack development diagram of floor,the test phenomena and results of three kinds of floor are described and analyzed respectively.The mechanical properties of the three plates with the same strain gauge position under static load are compared and analyzed.ABAQUS finite element software was used to compare and analyze the simulated and experimental values.According to the formula calculation,the author puts forward a temporary support scheme to solve the problem of prestressed steel pipe truss laminated bottom plate in the construction stage: when the span is less than 1.8m,there is no need to set temporary support;When the span is between 2.1m and 4.5m,a support needs to be set in the span.When the span is between 4.8 and 7.2m,two supports need to be set.The results of test and finite element simulation show that the prefabricated floor still has good deformation performance and overall bending performance after reaching the ultimate load.From the crack distribution,load-reinforcement strain curve and load-deflection curve,the composite bottom plate of prestressed steel pipe truss with supports has good crack resistance.The temporary support design makes the cracking rate of the specimen slower than that of the ordinary specimen,which not only greatly improves the bearing capacity of the specimen,but also significantly reduces the deflection.Thus,the deformation ability and rigidity of sample were increased.Based on FEM comparison,it is shown that the calculated results are similar to those obtained from experiments,and it can be concluded that the experiment is reliable and accurate,and it can be helpful for the application of compound board in project.Finally,the conclusion of the test is summarized,and the reasonable modification suggestions and further prospects of the test are put forward,which provide a strong basis for further research on the composite plate of prestressed steel pipe truss with supports.Figure [48] Table [23] Reference [62]...