基于整体提升技术的火灾后网架结构拆除方法研究

Research on demolition method of grid structure after fire based on overall lifting technology

整体提升施工技术逆向运用于达到使用年限或灾后受损需要拆除的结构中,将高空的整体结构逆向提升至地面完成拆除,此施工方法具有施工占地面积小、高空作业量小、安全性高等优点。以四川省某批发市场火灾后的屋面网架结构为例,针对基于整体提升技术的网架结构拆除方法进行研究。通过有限元软件MIDAS Gen,依次选取4组、5组、6组提升支架方案,分别按照吊上弦螺栓球和下弦螺栓球进行模拟计算,对比不同提升支架布置方案和吊点方案的变形和内力情况。计算结果表明,为减小结构变形和应力变化,在对称网架结构逆向提升施工中,应优先设置双数提升支架组数。同时,对网架进行了不同步逆向提升模拟计算,得出为避免结构显著不均衡变形,逆向提升施工时应将不同步量严格控制在15mm以内。工程实例应用结果表明,整体提升技术在屋面网架空间结构拆除施工中效率高,安全可靠,建议同类型工程施工使用此项技术。

The overall lifting construction technology is reversely applied to the structures that need to be demolished when the service life or post-disaster damage is reached,and reverse lift the high-altitude overall structure to the ground to complete the demolition.This construction method has the advantages of small construction area,small amount of high-altitude work,and high safety.Taking the roof grid structure after a fire in a wholesale market in Sichuan province as an example,the demolition method of the grid structure based on the overall lifting technology was studied.Through the finite element software MIDAS Gen,4 groups,5 groups,and 6 groups of lifting bracket schemes were selected in turn,and the simulation calculations were carried out according to hanging the upper chord bolt ball and the lower chord bolt ball respectively.The deformation and internal force of different lifting bracket arrangement schemes and lifting point schemes were compared.The calculation results show that in order to reduce the structural deformation and stress change,the even number of lifting bracket groups should be set first in the reverse lifting construction of the symmetrical grid structure.Simultaneously,the asynchronous reverse lifting simulation calculation of the grid frame was carried out,and it is concluded that in order to avoid the significant unbalanced deformation of the structure,the asynchronous amount should be strictly controlled within 15mm during the reverse lifting construction.The application results of engineering examples show that the overall lifting technology is efficient,safe and reliable in the demolition construction of the roof grid space structure,and it is suggested to use this technology in the same type of engineering construction.