基于改进广义坐标法的波形钢腹板组合箱梁扭转畸变耦合机理研究

Composite box girder bridges with corrugated steel webs have a lot of advantages, which are good for the sustainable development of bridge engineering. However, the lack of studies and related design methods for the torsion-distortion coupling has become an obstacle for the further spread of this kind of bridge structure. In this project, theoretical analyses, numerical simulations and modeling tests will be carried out to study the torsion-distortion coupling mechanism of composite box girders with corrugated steel webs. Detailed research topics are as follows..(1) For a composite box girder with corrugated steel webs subjected to both torsion and distortion, the stress state of the corrugated steel webs can be viewed as the combination of the plane stress state and the stress state of a thin slab subjected to bending. Moreover, the corrugated steel webs are anisotropic due to the accordion effect. For the abovementioned reasons, a reasonable equivalent orthotropic plane model will be developed for the corrugated steel webs..(2) Considering that the torsion-distortion coupling has not been considered in the existing torsion analysis of composite box girders with corrugated steel webs, an improved generalized coordinate method will be proposed to establish a new theory system for the torsion-distortion coupling effect..(3) Based on the new theory system proposed in this project, the influence of some key factors such as the thicknesses of the top and bottom concrete slabs, diaphragms, cantilever flanges on the torsion-distortion coupling effect will be deeply investigated..(4) Rational design suggestions and methods about the arrangement of diaphragms, construction requirements for torsion, and the eccentric loading coefficient will be proposed to improve the current design code for composite box girders with corrugated steel webs.

波形钢腹板组合箱梁桥拥有诸多利于桥梁工程可持续发展的优势，具有广阔的应用前景。然而，该类桥梁结构扭转畸变耦合分析理论和设计方法的缺乏已成为制约其进一步推广的关键因素。本项目通过理论分析、数值模拟以及模型试验，研究波形钢腹板组合箱梁扭转畸变耦合机理。具体如下：（1）波形钢腹板组合箱梁扭转畸变耦合作用下，波形钢腹板处于平面应力和薄板弯曲组合的受力状态，且褶皱效应使具有其各向异性。针对以上复杂问题，提出波形钢腹板合理的等效正交异性平面模型。（2）针对目前波形钢腹板组合箱梁扭转分析时多未考虑扭转畸变耦合的问题，提出改进的广义坐标法，建立研究该类结构扭转畸变耦合的新理论体系。（3）在新理论基础上深入、系统研究混凝土顶底板厚度、横隔板、悬臂翼缘板等关键因素对扭转畸变耦合效应的影响规律。（4）针对现有规范中该类结构在横隔设置、抗扭构造、偏载系数取值等方面尚未有明确规定的问题，提出合理设计建议及方法。

波形钢腹板组合箱梁桥拥有诸多利于桥梁工程可持续发展的优势，具有广阔的应用前景。然而，该类桥梁结构扭转畸变耦合分析理论和设计方法的缺乏已成为制约其进一步推广的关键因素。本项目通过理论分析、数值模拟以及模型试验，对波形钢腹板组合箱梁扭转畸变耦合机理进行了深入研究。主要研究工作和所得的主要结论如下：.（1）波形钢腹板组合箱梁扭转畸变耦合作用下，波形钢腹板处于平面应力和薄板弯曲组合的受力状态，且褶皱效应使具有其各向异性。针对波形钢腹板上述特点，基于板壳受力理论，创新性地使用静力凝聚法和力法，确定了可准确模拟波形钢腹板正交异性特性的合理等效力学模型。.（2）引入对传统广义坐标法进行扩展的GBT（Generalized Beam Theory），通过添加弯曲剪应变和纯剪应变引起的翘曲位移对GBT加以改进，以考虑剪应变、顶板悬臂翼缘和混凝土顶底板厚度对变形的影响。将确定的波形钢腹板等效模型引入改进GBT，基于能量变分原理建立平衡方程和边界条件，采用动力截面分析法确定其系数矩阵。开发基于python的差分法求解程序，实现了不同边界条件和荷载形式下波形钢腹板组合箱梁扭转畸变耦合效应分析理论体系和计算方法。.（3）对两根波形钢腹板组合箱梁试件进行偏心荷载作用下的试验研究，获得了箱梁挠度、正应力、剪应力、扭转角、扭率、扭转剪应变、剪力流等分布规律，根据试验结果和三位有限元模拟结果验证了改进GBT分析方法的可靠性。.（4）选取高跨比、宽跨比、横隔板设置、直幅段长度和波折角等设计参数作为影响因素，借助最优拉丁超立方试验方法，采用BP神经网络方法对影响波形钢腹板箱梁扭转性能的因素进行多参数敏感性分析。根据敏感性分析结果，深入研究了重要因素的影响规律。.（5）研究了《波形钢腹板组合梁桥技术规程》CJJ/T 272-2017中计算截面扭转惯性矩的适用性。另外，对《公路钢筋混凝土及预应力混凝土桥涵设计规范》(JTG3362-2018)建议的由扭转畸变和翘曲引起的截面附加正应力放大系数1.15进行了补充和修正。