超大跨度不对称混合梁斜拉桥成桥内力演化及调控的理论与方法

The existing theories and methodologies to determine and realize the reasonable completed state of cable-stayed bridge are mainly suitable for steel or concrete cable-stayed bridge, and they cannot meet the demand of higher accuracy of super long span asymmetrical hybrid cable-stayed bridge. There is a strong demand to establish a set of theory and methodology for evolution and regulation on internal forces for the complicated bridges. The important contents of the research are listed following: .A mechanical model is established to reveal the stiffness matching rules of main girder based on the mechanics properties of steel and concrete combined girder. Then a set of theory and algorithm is proposed to determine the reasonable completed state of hybrid cable-stayed bridge, which includes a theory with matched the flexural rigidity of steel-concrete girder based on the reasonable internal forces, a partitioning algorithm to determine the reasonable completed state and an optimization algorithm to calculate the final cable tensions. An efficient inversion algorithm for the reasonable structural system of hybrid cable-stayed bridges is established with suitable constraint conditions and optimal objects. Firstly, an optimum search algorithm is proposed to find the optimal location of the steel-concrete joint section. Then a computing method is also set up to determine the reasonable design parameters of the new type combination pylon. A self-adaptive construction control method of cable-stayed bridge with the zero stress configuration harmonious to the stress effect，which includes an adaptive adjustment algorithm which can deal with various error effect during the construction, and a control system and method which can take the combined effects into account. Then the final research aims to set up the theoretical basis of single joint closure method for the main girder of cable-stayed bridge. Its mechanical model is proposed to reveal this method how to influence the internal forces of bridge. A theory and algorithm is also established to obtain the scale of joint segment under zero stress state.

斜拉桥合理成桥状态确定的既有理论与实现方法主要针对预应力混凝土斜拉桥和钢斜拉桥，不能满足超大跨度不对称混合梁斜拉桥设计与施工的高精度要求，需对其成桥内力演化及调控的理论与方法进行深入研究。重点研究内容为：研究钢混结合主梁的受力特点，建立能反映刚度匹配关系的主梁成桥内力演化模型，揭示主梁刚度匹配规律；建立成桥状态各构件合理受力的判别准则，引入多因素耦合算法，建立钢混结合主梁合理恒载弯矩可行域的分步算法，进而建立索力的优化模型和高效求解方法；研究基于合理成桥状态的约束条件和优化目标，建立新型高效搜索方法，构建混合梁斜拉桥合理关键设计参数的反演算法；研制能计入多种误差的无应力构型自适应调整器，研究效应传递模型和精度映射关系，建立施工全过程无应力构型与混凝土应力效应协调的自适应控制方法；研究斜拉桥单缝合龙法的成桥内力调控力学模型，建立合龙段制造构型的精确算法，构建其主梁体系转换的理论基础。

1）为简化空间索面斜拉桥施工全过程分析中的计算模型同时确保计算精度，采用空间刚臂和斜拉索拖动坐标系构建了空间斜拉索平面等效计算模型的锚点位移模式，然后建立了索端位移和索端力的转换方程，推导了转换传递矩阵和空间斜拉索单元的平面等效单元刚度矩阵，并且当斜拉桥索面为平行索面时该矩阵也自动退化为平面带刚臂斜拉索单元模型。.2）提出了以最小弯曲能量法结合无应力索长为张拉控制条件的斜拉桥合理成桥状态确定的理论与方法。该方法按照施工顺序进行正装迭代计算，避免了倒拆法无法考虑混凝土收缩、徐变和结构几何非线性等因素的影响。.3）建立了考虑塔柱剪切不均匀系数的索塔横梁低温合龙机理，建立了中塔柱内力的施工主动调整算法，提出了索塔下塔柱的合理设计倾斜度。.4）研制了能计入钢箱梁制造线形、斜拉索无应力索长和主梁自重三种误差的主梁安装线形自适应调整器，能够确保斜拉桥的成桥状态与理论状态尽量保持一致。.5）基于薄壁截面剪力流理论，根据能量原理得到了薄壁截面剪应力不均匀系数的计算方法，推导了几种常见截面剪应力不均匀系数的计算公式。得到箱型截面剪应力不均匀系数随宽厚比的增大而增大，与常用计算方法对比，结果表明本文方法更合理，扁平箱型截面翼板部分的剪应力影响不可忽略。.6）研究开发了一种新型桥梁合龙装置—智能顶推阻尼系统，除为桥梁提供在脉动风、刹车和地震等的动力激励作用下时的阻尼耗能作用外，还可在桥梁主梁合龙的过程中为桥梁提供顶推和锁紧作用，实现全天候和智能化的合龙。.最后将理论与算法编制成软件，直接应用于一座920m级的混合梁斜拉桥上嘉鱼长江公路大桥上。实桥应用表明，建成大桥后的结构状态参数都比较理想，成桥状态与设计期望值符合良好。本项目研究成果为这座大桥的成功修建打下了坚实的理论和技术基础，同时也在逐步推广到了其它在建的特大型桥梁（如赤壁长江公路大桥，720m的组合梁斜拉桥）。