分组集聚式斜拉桥索塔锚固区传力机制

Mechanical behavior for anchorage zone of cable-stayed bridge with group aggregation anchor system

为研究新型分组集聚式斜拉桥锚固形式应力安全及钢-混传剪机理,以某公路大桥为背景,选取分组集聚索塔锚固节段为分析对象,运用有限元软件ABAQUS建立锚固区精细的数值模型.根据桥塔等效杆系模型的分析结果确定节段模型准确的荷载及边界条件,分别计算分析了3种工况下锚固区混凝土及钢横梁应力分布;通过对钢-混界面的各向应力及位移分布研究,探讨在不同程度预应力损失和钢-混界面摩擦系数影响下钢横梁与混凝土桥塔的传剪受力机理.研究结果表明:设计荷载工况下,钢横梁梁端剪力主要由界面静摩擦力承担,塔柱与钢横梁未发生相对滑动,具有足够安全储备;当锚杆预应力损失达到60%或接触面摩擦系数减小为0.2时,钢-混界面处于临界摩擦状态,相对滑移增大,结构处于相对不安全状态.

To analyze the stress safety and shear force-transferring mechanism between steel and concrete in cable-stayed bridge with group aggregation anchor system, which is a new architecture of the cable-stayed bridge, a finite element model of anchorage zone was established by ABAQUS software based on an actual bridge project. The loading and boundary conditions of the sectional model were determined according to the equivalent beam element model. The stress distributions of the concrete pylon and steel box girder under three load cases were studied. According to the analysis of stress and displacement of the interface between concrete pylon and steel box girder, the force-transferring mechanical performances with different levels of pre-tension loss and friction coefficients were investigated deeply. The analysis results show that the shear force at the end of the steel girder is mainly undertaken by friction in design load case, indicating there is no relative sliding between the concrete pylon and steel box girder with enough safety margin. When the pre-tension loss reaches 60% or the friction coefficient of interface reduces to 0.2, the critical friction state is achieved and relative sliding is increased, which makes the structure unsafe.