Research On Bearing Capacity Assessment And Reinforcement Of Plane Grid Structure Based On Member Damag

Plane grid structure,as a kind of large-span space steel structure,has the characteristics of good integrity,strong bearing capacity,reasonable economy and so on.It can provide a wide use space for buildings,and is widely used in gas stations,stadiums and other industrial and civil buildings.However,due to structural design errors,material defects,construction quality,load change and other factors,the truss rod may be damaged.The importance of the bar in the overall structure of the grid is determined by its contribution to the bearing capacity of the grid,which mainly depends on the position of the bar in the grid.Different rod damage will cause different degrees of impact on the structure.Due to the high redundancy of the grid structure and the large number of rod,the position and degree of rod damage are also varied,so it is difficult to directly observe the specific impact of various damage conditions on the bearing capacity of the structure.This thesis focuses on the topic of the bearing capacity assessment of the grid structure with rod damage,and explores the changing law of the bearing capacity of the grid structure after rod damage through the finite element simulation of different damage conditions.Combined with a large number of domestic and foreign scholars on the bearing capacity of the grid structure,the bearing capacity evaluation of the plane grid structure with rod damage can be studied.With the help of a domestic grid engineering example,this thesis also discusses the reinforcement scheme of the grid structure.The main research contents of this thesis are as follows:1.Through sap2000 engineering finite element software,the force analysis of the grid structure was carried out,and the distribution law of node displacement and rod stress at different positions of the grid structure was obtained.At the same time,the key of the control of node deflection and the weak point of the stress of the grid structure were pointed out,and the failure mechanism of the grid structure was summarized.This paper discusses the development history and existing problems of planar grid structure,and summarizes the research results of recent years on the bearing capacity and damage analysis of grid structure.2.According to the stress variation law of the bar after the damage of the bar in the grid structure,a method of calculating the importance of the bar based on the stress variation of the bar is proposed in this paper.This method simplifies the complicated calculation process,increases the difference of the importance coefficient of the bar,and makes it easier to identify the more important position of the bar.The stress of the grid structure after rod damage is analyzed,and the three types of rod in the grid structure: upper chord rod,abdominal rod and lower chord rod are simulated in different damage positions and different damage degrees.By comparing the changes of rod stress and node displacement,the important rod that affects the bearing capacity of the grid structure is found out.3.Based on the change law of mechanical index of the lattice structure after the damage and the research of other scholars on the damage assessment of the lattice structure,this paper proposes a new damage factor calculation model of the grid structure,and evaluates the bearing capacity of the grid structure according to the response description of the grid structure.Through the simulation of different positions and different numbers of damaged rods in the grid frame,the change law of the bearing capacity of the grid frame with the increase of the number of damaged rods is discussed.The different effects on the structure of the grid when the location of the damaged rods is concentrated and dispersed are compared and analyzed.4.Aiming at the problem of reinforcing the grid structure with multiple rod damage,this paper proposes a reinforcement method based on the importance of the rod,which can effectively improve the bearing capacity of the grid structure and ensure the safety of the reinforcement process.This paper takes the plane grid of a conference center as an example,analyzes the damage situation of the structure and puts forward the reinforcement scheme,which has a certain engineering reference value.