Experimental And Theoretical Study On Cast-in-place Steel Bar Truss Concrete Slab

In recent years,the state has vigorously developed the steel structure and assembly type building,while achieving green construction,improving construction standards,quality and efficiency,and realizing the industrialization of the construction industry.Under such circumstances,the emergence of new structure is inev itable,and the steel truss floor is born.Steel Bar Truss Slab is a composite slab model,which are developed on the basis of composite slabs with profiled steel sheet,formed by welding steel truss on galvanized steel sheet,a bottom die and support cast-in-place floor.The binding capacity of the site is small,compared with the cast-in-place floor,the binding capacity is less than 70%,the arrangement of the steel bars is even,the positioning of the steel bar is simple,and the utility model has the unique advantages.According to existing research,steel truss floor plate stress performance superior to the ordinary concrete floor.In order to study stress performance of the long span plate and damaged steel truss floor plate,this paper is mainly on the 4000mm*600mm steel truss floor plate test and theory research,the test steel truss floor plate supported by Sichuan Andecheng building materials Co.Ltd.,welded directly in the factory.Two pieces of full floor slabs are designed for B1# and B2#,and two plates are made of the same type and specification.the upper chord、bottom chord and web member reinforced steel bar diameter were 12 mm,10mm,6mm,The thickness of the bottom galvanized steel is 0.5mm,the height of the reinforced truss is 150 mm,the thickness of the concrete slab is 180 mm.,additional transverse reinforcement 12@200,and the transverse reinforcement is directly welded with upper chord,both ends of the floor are simply supported.In order to investigate the influence of the rust failure of the galvanized steel sheet on the mechanical properties of the slab,the bottom galvanized steel sheet was cut along the width of the slab in the middle of the B2# floor after pouring the concrete and maintaining the strength.The static loading test of the B1# and B2# floors was carried out,and the test results were compared and analyzed.In this experiment,the advanced finite element analysis software MSC.Marc was used to establish the analysis model of the construction stage and the use stage,and the numerical simulation analysis was carried out.According to the results of the finite element software analysis,the maximum deflection value of the reinforced truss plate under the concrete load and the construction uniform load is-18.21 mm,which basically meets the requirements of the strain control in the construction stage.Under the load of 6kN/m2,the overall deflection of the B1# floor is-0.682 mm,the overall deflection of the B2# floor is-0.683 mm,and the maximum deflection of the B1# and B2# floors under the load of 8kN/m2 is-0.910 mm And-0.911 mm.The deformation results show that the bottom steel slab has little effect on the floor plate,and the strain value and the overall deflection of the steel are linearly changed with the increase of the load,so the floor B1# and B2# are in the elastic stage.Through the comparison of B1# and B2# floor test data,the influence of the bottom plate on the bearing capacity of the bearing plate is obtained.According to the test results,B1# floor cracking load value of 15.75kN/m2,bending moment value of 18.15 kN.m,crack width of 0.2mm load value of 26.25kN/m2,bending moment value of 30.25 kN.m,the load value at break is 42.0kN/m2 and the bending moment is 48.4 kN.m;the cracking load of B2# floor is 11.62kN/m2,the bending moment is 12.98 kN.m and the crack width is 0.2 mm.16.9kN/m2,bending moment value of 18.88 kN.m,damage to the load value of 27.45 kN/m2,bending moment value of 30.68 kN.m.You can see the cracking load of the B1# floor,the damage load value is greater than the load value of the B2# floor,the bottom of the steel plate can be obtained on the steel truss floor bearing a certain contribution to the bottom of the steel plate damage to the overall Carrying capacity has a great impact.Because of the pulling effect of the bottom galvanized steel sheet,the bearing capacity of B1# and B2# floors is improved compared with the traditional reinforced concrete floor,and the deformation ability is large,which will play a role in exploring the design method of reinforced steel truss.