| Prefabricated laminated slab is one of the most widely used floor structures at present.The prestressed concrete steel tube composite plate has the advantages of high production efficiency,large space for pipeline layout,and the bottom plate is not easy to damage.In the preliminary research work,it is found that the composite plate has relatively excellent mechanical performance,and the existence of steel tube and prestressed steel bar significantly enhances the bearing capacity and stiffness of the composite plate.In this dissertation,numerical simulation method is used to compare the mechanical properties of the composite slab and the ordinary truss reinforced composite slab,and the stress analysis of the composite slab in the construction stage and the use stage is carried out,and the optimization design of the prestressed concrete steel tube truss composite slab is carried out in combination with the actual project.The main work is as follows:(1)The model of prestressed concrete steel tube composite plate was established by finite element software,and the correctness and effectiveness of the model was verified by comparing with the results of composite plate test and theoretical analysis in the previous stage.(2)Through the force analysis of the prefabricated base plate and the ordinary reinforced truss superimposed plate base plate in the construction stage,it was found that the composite plate better mechanical properties compared to common truss composite board.We analyze the force performance of the prestressed concrete steel tube composite slab through the deflection of the slab span,the prestressed steel bar and the force state of the steel pipe,and analyze the parameters that affect the force of the precast bottom plate.The results show that the height of the bottom steel pipe truss.And the increase in the thickness of the prefabricated bottom plate can better improve the load-bearing capacity of the laminated board.(3)The finite element models of monolithic,two-piece and three-piece composite plates were established respectively,and the stress states in elastic stage and plastic stage were analyzed.The finite element results show that the stress characteristics of threepiece prestressed concrete steel tube composite plates are closer to that of monolithic composite plates.The composite floor slab precast floor flat-fell seam were analyzed,and the change of floor flat-fell seam steel reinforcement ratio,the thickness of the composite layer and flat-fell seam on both sides of the three parameters truss spacing are studied,we found that the composite had a greater influence on the thickness of flat-fell seam stress,flat-fell seam reinforcement have less effect on the composite board’s flat-fell seam,but when the seam lap joint spacing is bigger,flat-fell seam on both sides of prestressed reinforcement will bear big bending moment.The increase in the number of split-seam lap bars is beneficial to reduce the force at the split-seam of composite plates.(4)In the practical engineering,the prestressed composite slab flat-fell seam is easy to the problem of craze,the increase of truss bars on both sides of the seam measures are put forward,and the finite element modeling analysis.Results show that the steel bar truss can effectively increase the bearing capacity of the composite plate flat-fell seam,and appropriately reduce flat-fell seam truss spacing,can reduce the deformation of composite floor slab flat-fell seam,Improve the anti-cracking ability of bottom plate.(5)Combined with engineering examples,we optimize the structure design of prestressed concrete steel tube composite floor.Under the constraints of the structure,strength and crack of the main and secondary beams of the composite slab,the optimal layout of the beam and plate,the optimal size and reinforcement of the beam and plate were obtained by taking the size of the secondary beams and the plate as the design variables and the total cost of the floor as the objective function. |
