Research On Reinforcement Technology Of Frame Structure Floor With Extra Large Load

With the rapid development of China’s construction industry,the use function of existing buildings has changed,and more and more projects need to be strengthened.In order to ensure the safety and reliability of the reinforcement project,it is particularly important to study the floor reinforcement scheme and the static characteristics and overall seismic performance of the structure after floor reinforcement.In this paper,based on the reinforcement project of the new steel beam system at the bottom of the floor slab of a water education early education center in Lanzhou,the finite element models of the strengthened floor and the whole building before and after the floor slab reinforcement are established by using the general finite element software,and the cooperative performance of the reinforced steel beam system and the original frame structure under static and dynamic action is studied respectively,The main conclusions are as follows:(1)When the design load is 12.5k N/m~2,the yield load and ultimate load of the floor can be increased by 55.26%and 157.91%respectively,The results show that the yield load and ultimate load of the floor can be increased by 36.13%and 126.25%compared with those before reinforcement.The sliding effect reduces the bearing capacity of the floor.Before reinforcement,the floor reinforcement of the whole frame structure reaches its yield strength first under the action of super large floor load.After reinforcement,the bearing capacity of the floor is significantly improved.Under the action of super large floor load,the reinforced steel beam 2A yields before the floor reinforcement,It shows that the load of the original floor is greatly reduced by the reinforcement steel.(2)When the design load is 12.5k N/m~2,the sliding effect of the floor and the reinforced steel has an impact on the floor deflection.The deflection is 8.492mm when the sliding is not considered,and 10.71mm when the sliding is considered,but both are less than the code limit of 15.7mm.The floor deflection increases with the increase of the anchor bolt spacing.When the anchor bolt spacing is less than 50mm,it can be considered that there is no relative sliding,They can work together completely.(3)The linear static analysis results show that the maximum horizontal displacement of the joints along the short span direction is reduced by 18.38%,and the maximum horizontal displacement along the long span direction is reduced by 4.57%,which indicates that the lateral stiffness of the whole frame structure is increased after the floor reinforcement,and the increase in the short span direction is larger.(4)Compared with the natural vibration period and mode of the frame structure before and after the floor reinforcement,the period of the first three modes of the structure after the floor reinforcement is reduced by 5.94%,1.20%and 4.44%respectively.The first mode of vibration is translational motion along the short span direction before the floor reinforcement,and the first mode of vibration is translational motion along the long span direction after the floor reinforcement.(5)The dynamic elasto-plastic time history analysis results of the whole building under rare earthquake show that under the action of three seismic waves,the top floor acceleration and base shear force of the structure before and after reinforcement increase,and the floor displacement decreases obviously.The top floor acceleration increases by 5.88%and 8.01%respectively along the long span and short span direction before and after reinforcement,and the base shear force increases by 5.88%and 8.01%respectively along the long span and short span direction The maximum floor displacement increases by 19.12%and 32.88%respectively in the short span direction.The maximum floor displacement decreases by 6.56%and 45.36%respectively in the long and short span direction before and after floor reinforcement.The results show that the damage of beams,slabs and columns on the second floor is obviously reduced,but the damage of the first and third floor is not obvious.