初始偏位梁式桥墩柱力学性能分析

对于中小跨径梁式桥,墩高较大且墩柱数量较多,施工过程中墩柱偏位现象时有发生。围绕墩柱初始偏位,归纳墩柱偏位出现类型,分析其内力分布特征,并以某墩柱偏位超限高墩连续梁桥为例,建立全桥杆系结构与墩柱实体结构有限元模型,分析墩柱偏位超限对主梁、墩柱的内力、变形及稳定性的影响。结果表明:从理论上,墩位偏位后将产生附加的弯矩、剪力和轴力,放大墩柱的压弯剪作用,改变墩位的受力状态,甚至使最大弯矩出现位置发生改变;文中实例属于缺陷墩,但桥梁结构的固有频率、屈曲模态、地震响应特性、主梁的内力及变形无明显变化。形成缺陷墩后,墩柱最大弯矩略有增加,钢筯压应力值有所增大,而钢筋拉应力及混凝土主拉应力均无明显变化。

Study on Mechanical Properties of Girder Bridge Pier with Initial Bias

For small and medium span girder bridges,the pier height is larger and the number of pier columns is larger,and the deviation phenomenon of pier column occurs sometimes in the construction process.Based on the initial deflection of pier column,this paper sums up the types of pier column deviation,analyzes its internal force distribution characteristics,and establishes the finite element model of the whole bridge bar system structure and pier-column solid structure by taking a continuous beam bridge with pier-column deviation beyond the limit of high piers as an example,and establishes the finite element model of the whole bridge and the pier-column solid structure to study the influence of the deviation limit of Pier column on the internal force,deformation and stability.The results show that,theoretically,additional bending moment,shear force and axial force will be produced after piers deviate,and the bending and shear action of pier column will be enlarged,the stress state of pier position will be changed,and even the position of maximum bending moment will be changed.The example in this paper belongs to the defective pier,but the natural frequency,buckling mode,seismic response characteristics,internal force and deformation of the main beam have no obvious changes.After the formation of defective pier,the maximum bending moment of pier column increases slightly,and the compressive stress value of steel increases,while the tensile stress of steel bar and the principal tensile stress of concrete have no obvious change.