深坑大跨屋盖重型钢桁架结构吊装施工过程监测研究

Research on construction process monitoring on heavy steel truss lifting process of deep pit large-span roof

为探究大跨度钢结构屋盖在施工过程中的荷载转换机理并保证大跨桁架结构吊装过程安全,针对某深坑大跨屋盖结构中单榀重型主桁架的吊装及安装全过程进行了结构应变监测。通过在结构关键截面位置处布设应变传感器,对施工过程中结构关键位置的真实应变分布情况进行分析,从而评估施工过程中结构的安全性。基于大型有限元软件ABAQUS建立精细化有限元模型,将吊装完成后结构测点处的应变响应与有限元计算得到的应变进行了对比。结果表明:结构在吊装过程中的整体应变响应水平较低,该桁架结构被吊装到位后,受焊接固定工作的影响,结构的应变发展情况较为复杂,但总体仍处于安全范围之内;安装完成后,整体结构的应变水平随外部环境气温升降呈现周期性变化规律;环状加劲板与底部混凝土间钢板受力最大,格构柱内侧中部受力偏大,格构柱外侧两端受力偏大,桁架部位受力集中在跨中范围内,两侧受力偏小,且结构内部加劲板和格构柱间底部混凝土明显降低了结构关键节点的受力。

In order to explore the load conversion mechanism of large-span steel structure roof during construction and ensure the safety of large-span truss structure lifting process,the structural strain monitoring was carried out for the whole process of lifting and installation of single heavy main truss in a deep pit large-span roof structure.By arranging strain sensors at the key sections of the structure,the real strain distribution at the key positions of the structure during the construction process was analyzed to evaluate the safety of the structure during the construction process.Based on the large-scale finite element software ABAQUS,a refined finite element model was established,and the strain response at the structural measuring point after lifting was compared with the strain calculated by the finite element method.The results show that the overall strain response level of the structure during the lifting process is low.After the truss structure is hoisted in place,the strain development of the structure is complicated due to the influence of welding and fixing work,but it is still within the safe range.After the installation is completed,the strain level of the whole structure changes periodically with the temperature rise and fall of the external environment.The stress of the steel plate between the annular stiffening plate and the bottom concrete is the largest,the stress of the middle part of the inner side of the lattice column is too large,the stress of the two ends of the outer side of the lattice column is too large,the stress of the truss part is concentrated in the middle span,and the stress of the two sides is too small,and the internal stiffening plate and the bottom concrete between the lattice column significantly reduce the stress of the key nodes of the structure.