摘要:
空间网格结构因其独特的建筑造型,在现代建筑中应用越来越多,随着其下方主体结构和空间网格结构越来越复杂,其结构安装技术也在不断地提升和改造。对于下部支承结构较为复杂的单层三向网格结构,常规采用临时支撑胎架进行原位分块安装或者搭设满堂脚手架高空散装的方式都存在措施量大、成本过高、安拆时间长等问题,而液压整体同步提升、顶升以及滑移等新型施工方式不仅同样存在成本和效率问题,而且还有较高的施工难度。针对上述问题,以深圳市“互联网+”未来科技城地块DY01-04街坊西区下沉广场马鞍形单层三向网格穹顶结构为例,对其无支撑施工关键技术进行研究,以实现更少的临时支撑措施量和更高的施工效率。无支撑施工指采用特定的分块方式,能充分利用上一个吊装单元作为下一个吊装单元的支撑结构,以交错搭接的方式,不设临时支撑完成结构的安装。施工的关键在于所采用的特定分块方式划分出的每一个分块均能够在吊装完成后与前一步安装结构形成稳定的结构体系,这个稳定的结构体系与一次设计成型态相比不会产生过大的位移和应力。基于施工全过程仿真分析和现场实测数据,综合考虑了施工过程的安全性、便利性及经济性,对螺旋式、单向交错式和对称交错式三种无支撑施工方式进行对比研究。结果表明,单层三向网格结构无支撑施工安全可靠,施工完成态结构应力及变形与设计一次成型态接近,结构整体应力较小,且环梁施工过程无稳定性问题,安全储备充足;无支撑螺旋式施工分段长度更短,结构应力及变形整体都优于无支撑交错式施工,无支撑对称交错式施工可显著减少单向施工过程中“跷跷板”效应带来的结构额外应力和变形,因此又优于无支撑单向交错式施工;通过在结构位移和应力模拟值较大处布置变形和应力监测点,对结构无支撑螺旋式施工过程中的变形和应力进行监测,监测结果表明:实际结构变形和应力与MIDAS模拟分析结果在发展变化趋势及数值上总体保持一致,体现了无支撑螺旋式施工方案的合理性。
Abstract:
The space grid structure is increasingly utilized in modern architecture due to its unique architectural design. With the growing complexity of space grid structure and the main structure below it, the structural installation technology is continuously improving and evolving. For a single-layer three-way grid structure with a complex lower supporting structure, the conventional method of installing insitu block installation using temporary supporting frameworks or erecting full-height scaffolding for high-altitude bulk installation poses challenges such as excessive measures, high costs, and long dismantling times. New construction methods like hydraulic overall synchronous lifting, jacking, and skidding not only face issues of cost and efficiency but also involve higher construction difficulty. Addressing the mentioned issues, the key technology of unsupported construction is studied, taking the saddle-shaped single-layer three-way grid dome structure in the sunken plaza of Shenzhen’ s “ Internet+” Future Science and Technology City Lot DY01-04 as an example, aiming to achieve fewer temporary support measures and increased construction efficiency. Unsupported construction involves using a specific blocking method to fully utilize the previous lifting unit as the support structure for the next unit and complete the installation in a staggered manner without temporary support. The key to the construction is that each block divided by the specific blocking method can form a stable structural system with the previous installation structure post-lifting completion, preventing excessive displacement and stress compared to the one-time design pattern. Through simulation analysis of the entire construction process and onsite monitoring data, and considering safety, convenience, and cost-effectiveness of the construction process, a comparative study of three unsupported construction methods-spiral, unidirectional staggered, and symmetric staggered is conducted. The study indicates that unsupported construction for single-layer three-way grid structures is safe, reliable, and close to the design state in terms of structural stress and deformation after completion, with minimal overall structural stress and no stability issues in the construction process of the ring girder, showing sufficient safety margin. Unsupported spiral construction has a shorter segment length, better structural stress and deformation of the total structure compared to unsupported interlocking construction, while unsupported symmetric staggered construction effectively reduces the additional stress and deformation caused by the “ see-saw ” effect in the construction process, making it superior to unsupported unidirectional staggered construction. By placing deformation and stress monitoring points where simulated structural displacements and stresses are significant, monitoring the structural deformation and stress during the construction process reveals that the actual structural deformation and stress align closely with MIDAS simulation and analysis results in trend and numerical value, demonstrating the rationality of the unsupported spiral construction scheme.