大悬臂连续钢箱梁桥整孔安装的精细化分析及施工参数计算

Refined analysis and construction parameter calculation for full-span erection of the continuous steel box girder bridge with long cantilevers

目的:以港珠澳大桥连续钢箱梁桥为工程背景,探究适用于模拟全桥全施工阶段且具有高精度的空间有限元方法,并分析整孔安装的关键施工参数,从而高效准确地控制大型复杂桥梁结构的整孔安装精度。创新点:1.采用基于网格分离的空间强化有限元法,能够在保证精度的同时简化复杂结构的网格剖分问题,且适用于任意边界、构造及荷载的空间分析。2.在三维实体单元的基础上引入退化板单元,并对不同物理单元的本构关系矩阵进行修正,使其适用于薄壁结构分析。3.精确计算施工控制参数,以有效地指导连续钢箱梁的整孔安装过程。方法:1.采用空间强化有限元法,并引入退化板单元,对连续钢箱梁桥进行全桥全施工阶段分析。2.基于结构响应,计算相邻节段间的端面转角、节段预偏距和温差效应等关键参数以控制整孔安装施工精度,并与传统有限元法及工程实测数据进行对比验证。结论:1.相较于传统有限元法,空间强化有限元法更高效,且其精度满足工程要求。2.根据各施工阶段的结构响应,可以精确地控制梁段高程,以及识别和校核最不利荷载位置。3.精确地控制相邻节段在无应力状态下的端部转角、梁段预偏距和箱梁顶底板温差等施工参数,能够使梁段平顺连接,使最终支座处于正位状态,并避免温差效应的影响,从而实现对整孔安装施工的高精度控制。

To accurately control the full-span erection of continuous steel box girder bridges with complex cross-sections and long cantilevers, both the augmented finite element method(A-FEM) and the degenerated plate elements are adopted in this paper. The entire construction process is simulated by the A-FEM with the mesh-separation-based approximation technique, while the degenerated plate elements are constructed based on 3D isoparametric elements, making it suitable for analysis of a thin-walled structure. This method significantly improves computational efficiency by avoiding numerous degrees of freedom(DoFs) when analyzing complex structures. With characteristics of the full-span erection technology, the end-face angle of adjacent girder segments, the preset distance of girder segments from the design position, and the temperature difference are selected as control parameters, and they are calculated through the structural response of each construction stage. Engineering practice shows that the calculation accuracy of A-FEM is verified by field-measured results. It can be applied rapidly and effectively to evaluate the matching state of girder segments and the stress state of bearings as well as the thermal effect during full-span erection.