Research On Member Maintainability Evaluation Of Spatial Grid Structure

Spatial grid structure is more and more used in all kinds of long-span buildings because of its good adaptability to the span of the structure.The structure has good mechanical characteristics,various structural forms,and light weight,which can save materials.In practical engineering,due to material defects,uncertain load effects,improper management and other reasons,the structural members are prone to failure,and in serious cases,the structure will collapse continuously.Proper maintenance of damaged or failed members is very important for the safety of the structure.However,it is time-consuming and laborious to repair the less damaged member or the member located in the unimportant position of the whole structure.Therefore,the concept of maintainability is put forward in this paper.Evaluate the extent to which maintenance measures are required after the member is damaged.Firstly,this paper evaluates the bearing capacity of a single bar subjected to bending damage and local sag damage,and determines the extent of damage to the bar needs to be repaired.Because the importance of the member is different,the grade evaluation of the member after damage is also different,so it is necessary to evaluate the importance of the member to the whole structure.Based on the traditional evaluation of the importance of the members,this paper proposes a method for evaluating the importance of the members based on the structural dynamic characteristics.Based on the removal of the members,the importance of the member to the structure is evaluated by comparing the degree of change of the dynamic characteristics of the structure before and after the removal of the member.Secondly,based on the probability reliability,the sensitivity analysis of the members of the spatial grid structure is carried out from the point of view of the bearing capacity of the structure.The two methods are used to analyze the bar members of the flat quadrangular pyramid structure and the single-layer cylindrical reticulated shell structure,and the distribution of the important degree of the structural members is determined.Finally,aiming at the chord dome roof structure of a practical project,the importance analysis and sensitivity analysis of each part of the members are carried out by using the importance evaluation method and the sensitivity evaluation method of the members in this paper.The distribution law of the importance of the members of the chord-supported dome structure is obtained.Because of the particularity of the prestressed cable,this paper also discusses the situation that the cable needs to be replaced in view of the damage of the cable,puts forward and compares the different cable replacement schemes,and analyzes the importance of the cable.The feasibility of cable replacement and the influence of prestressed cables on the structure are verified.This paper evaluates the members of the space grid structure,and guides the maintenance problems of the rods that may occur in the practical project.According to the importance of the rods and the degree of damage of the rods,the repairability of the rods is judged.The maintenance measures to avoid serious accidents have practical significance.