某大跨V形柱高空散拼施工过程模拟分析

Simulation Analysis of High-altitude Scattered Assembly Construction Process of a Long-span V-shaped Column

空间钢结构形式多样,造型优美,是一种具有三维空间形体、三维受力特性的结构。然而随着建造技术的提升,国内出现了许多异形柱、变标高空间桁架、大跨度桁架等安装施工难度较大的钢结构形式,呈现出跨度大,受力复杂的特点。以南阳南站工程中大跨不等高桁架屋盖为载体开展研究,由于不等高大跨空间桁架施工工艺复杂,加之有较大悬挑跨度,使得下部V形柱产生了较大变形及高应力。该工程为空间倒三角钢桁架结构,悬挑部分达到25 m,属于大跨度悬挑结构。由结构受力方面分析可知,大跨度悬挑结构受力不利。首先,在竖向力及水平力的作用下,悬挑根部的弯矩及剪力都很大,根部的节点受力复杂,容易成为薄弱点,一旦此处因为应力较大而破坏,将会使整个结构形成机构造成整体结构的坍塌或倾覆。其次,悬挑结构对竖向抗震十分敏感,若是悬挑长度大且悬挑部分自重大,这种效应将会十分明显。第三,悬挑结构的整体稳定性较差,需要对结构的抗倾覆性进行验算,并有针对性地采取一些平衡措施。综合考虑适合本工程的方案,宜采用常规的分段吊装方法,其具有可操作性强、安全系数高等优点。为此采用MIDAS分析软件对V形柱高空散拼的施工过程进行有限元模拟,以保证后续施工的安全和效率;并采用ANSYS分析软件对V形柱的关键连接点进行计算分析,通过增加y型补强板的补强措施,保证工程的安全和质量。结果表明:1)柱装配过程中结构应力变化为从第一段安装的8.65 MPa逐步增加到31.9 MPa,位于柱脚底部,处于弹性工作状态。2)柱装配过程中结构最大变形位于悬挑区,其值为9.54 mm,小于挠度规定限值,且应力为31.9 MPa,满足要求。3)柱在拼接过程中,最大变形和最大应力均在柱悬挑区装配过程中产生,通过构造加强后,节点应力及变形能更好满足“强节点弱杆件”的设计准则。

Spatial steel structure has various forms and beautiful shapes. It is a structure with three-dimensional shape and three-dimensional stress characteristics. However, with the improvement of construction technology, there are many steel structures with great difficulty in installation and construction, such as special-shaped columns, variable elevation space trusses and long-span trusses, showing the characteristics of long span and complex stress. Taking a long-span unequal height truss roof of Nanyang South Railway Station as the carrier, the construction technology of unequal high-span space truss is complex, and there is a large cantilever span, which produces large deformation and high stress on its lower V-shaped column. From the perspective of the project itself, the project is a spatial inverted triangular steel truss structure with a cantilever part of 25 m, which belongs to a long-span cantilever structure. According to the analysis of structural stress, the stress of long-span cantilever structure is unfavourable. Firstly, under the action of vertical force and horizontal force, the bending moment and shear force at the root of the cantilever are large, and the stress of the node at the root is complex, which is easy to become a weak point. Once it is damaged due to large stress, the whole structure will form a mechanism, resulting in the collapse or overturning of the whole structure. Secondly, the cantilever structure is very sensitive to vertical earthquake resistance. If the cantilever length is large and the cantilever part is self significant, this effect will be very obvious. Third, the overall stability of the cantilever structure is poor, so it is necessary to check the overturning resistance of the structure and take some targeted balance measures. Considering the scheme suitable for the project, the conventional sectional hoisting method should be adopted, which has the advantages of strong operability and high safety factor. The high-altitude welding quality can also be controlled through targeted measures to ensure the project quality, as well as the simulation analysis of finite element software in the construction process, the simulation of three-dimensional dynamic model used in the hoisting process, real-time interference detection, so as to ensure that the components are installed in place, and the construction scheme can be optimized in time to ensure construction safety and construction efficiency. Therefore, the main research contents of this paper: use MIDAS analysis software to simulate the construction process of V-shaped column with high-altitude scattered assembly, so as to ensure the safety and efficiency of subsequent construction;ANSYS analysis software is used to calculate and analyze the key connection points of V-shaped column, and then corresponding reinforcement measures are taken to ensure the safety and quality of the project. The results show that: 1) the structural stress changes gradually from 8.65 MPa to 31.9 MPa during column assembly, which is located at the bottom of column foot and in elastic working state. 2) In the column assembly process, the maximum structural deformation is located in the cantilever area, and its value is 9.54 mm, which is less than the specified limit of deflection, and the stress is 31.9 MPa, which meets the requirements. 3) In the process of column splicing, the maximum deformation value and maximum stress are generated in the assembly process of column cantilever area. After structural strengthening, the joint stress and deformation can better meet the design criterion of "strong joint and weak member".