Study On Fire Behavior Of Two-way Concrete Slabs With Three Edges Clamped And One Edge Simply Supported

The horizontal load-bearing plate is widely used in the practical structural engineering.The study of its fire behavior is of great significance for improving the fire resistance design of the structure and protecting the safety of people’s life and property.Through the research on the performance of different types of concrete slab at ambient temperature and high temperature by domestic and foreign scholars,many measures to improve the fire resistance of the structure are put forward,however,there is a lack of discussion on the influence of boundary support conditions on the fire performance of full-size plate members.It is of great engineering value to study the fire behavior of the bottom surface of the three edges clamped and one edge simply supported two-way slab.Therefore,this dissertation will study the fire behavior of a full-size reinforced concrete two-way slab whose boundary condition is simply supported on one edge and clamped on the three edges.The main research content is as follows:(1)Under the condition of constant load and temperature rise,fire tests were carried out on two bidirectional plates with axis size of 7.15m× 5.65 m and three clamped edges and one simply supported edge.Two sets of force transfer devices are designed to realize the boundary condition of the fixed end,and the fixation effect is obvious.In the course of the tests,the crack development process and the ultimate deformation and failure characteristics of the slab are recorded,while the temperature field of concrete and steel bar in the direction of slab thickness,the displacement change in and out of the plane and the change in the corner of slab at the center of the axis are measured analyzed.(2)Under the joint action of high temperature and load,the crack of the plate surface finally presents an inverted U shape,and the opening direction is simply supported.The central area of the plate generally shows a subsidence trend,and the sinking area presents a "basin" state in which the deflection change near the fixed support end of the short edge is less than that near the simply supported end,and the test plate is slightly shifted towards the simply supported end of the short edge.Theburst phenomenon of plate bottom is serious,concentrated in the area close to the fixed support end of the short edge along the length direction and the maximum burst depth is 8 cm,showing the characteristics of large depth and wide range.(3)In the case of fire,the temperature field of concrete and steel bar along the direction of slab thickness has an obvious gradient change.The deflection deformation is the largest in the central part of the plate,and the restraint of the fixed end has obvious inhibition on the deflection deformation,while the deflection deformation near the fixed end is relatively small.The in-plane displacement of the plate does not fluctuate much during the fire test,and the maximum in-plane displacement appears at the simply supported end.The edge of the plate rotates perpendicular to the axis,and the restraint of the fixed end also inhibits the corner rotation of the plate.(4)ABAQUS software was used for numerical analysis of the test plate to prove the temperature field in the plate and the law of overall deformation auxiliarily.The numerical simulation data is consistent with the experimental results,and the model is relatively reliable...