Research on the Mechanical Properties of the Overall Lifting/Lowering Process of the Grid Structure Construction
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摘要: 网架结构因其受力简单、刚度大、自重轻、施工便捷及整体稳定性好等优点,己被广泛地运用于各类工业、民用基础设施建筑中。网架结构常用的施工方法有高空散装法、分条/块安装法、滑移法、整体吊装法、整体顶升法以及整体提升法,其中整体提升法具有杆件拼装质量高、提升过程结构稳定性好、所需胎架数量少等优点,因此成为大跨度空间网格结构的常用施工技术之一。以非同步提升和断索效应为研究对象,系统探究网架结构施工中的提升及下放过程的力学性能。进行了整体提升非均匀性对网架整体提升力学性能影响及非均匀性下放对网架整体提升力学性能影响研究,考虑了整体结构某一方向位移差和单一吊点位移差等情况,分析得到了提升非均匀性对整体提升结构应力、反力的影响程度。研究结果表明:当位移差超过20 mm时,结构应力和吊点反力对非同步性的敏感度显著增加;位移差达60 mm时最大应力接近安全限值,X方向最大反力超过3000 kN;考虑动力效应后结构跨中挠度较静力分析结果增大约20%。基于上述发现,建议将施工同步控制限值设定为20 mm,提升初期采用较低速度0.02 m/s以抑制动力波动。Abstract: The grid structure has been widely applied in various industrial and civil infrastructure buildings due to its advantages such as simple force-bearing, high stiffness, light self-weight, convenient construction, and good overall stability. The common construction methods for grid structures include the high-altitude bulk installation method, the strip/block installation method, the sliding method, the overall hoisting method, the overall jacking method, and the overall lifting method. Among these, the overall lifting method has the advantages of high assembly quality of the members, good structural stability during the lifting process, and fewer required formwork frames. Therefore, it has become one of the commonly used construction techniques for large-span spatial grid structures. This paper focuses on the non-synchronous lifting and breakage effect as the research objects, and systematically explores the mechanical properties of the lifting and lowering process in the construction of grid structures. Studies were conducted on the influence of non-uniformity of overall lifting on the mechanical properties of the overall lifting of the grid structure and the influence of non-uniform unloading on the unloading process. Considering situations such as displacement difference in a certain direction of the overall structure and displacement difference at a single lifting point, the impact of non-uniformity on the stress and reaction forces of the overall lifting structure was analyzed.The research results indicate that when the displacement difference exceeds 20 mm, the sensitivity of structural stress and lifting point reaction force to asynchronousity increases significantly. At a displacement difference of 60 mm, the maximum stress approaches the safety limit, and the maximum reaction force in the X-direction exceeds 3000 kN. After considering dynamic effects, the mid-span deflection of the structure increases by approximately 20% compared with the static analysis results. Based on the above findings, it is recommended that the construction step control limit be set at 20 mm, and a low initial lifting speed of 0.02 m/s be adopted to suppress dynamic fluctuations.
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