部分填充混凝土矩形钢管组合桁梁桥冲击系数

为研究部分填充混凝土矩形钢管组合桁梁桥车激动力放大效应,以某3跨连续部分填充混凝土矩形钢管组合桁梁桥为研究对象,通过桥梁冲击系数定义求得桁梁桥挠度冲击系数与轴力冲击系数。对比分析了不同车速、桥面不平度、车重、填充系数等因素对桁梁桥冲击系数的影响,并采用MATLAB软件对共867个冲击系数进行拟合优度检验,得到95%保证率下桁梁桥冲击系数统计值。结果表明：部分填充混凝土后能有效降低矩形钢管组合桁梁桥下弦杆动力响应,但并没有降低桁梁桥在车辆荷载作用下的动力放大效应；车速对桁梁桥冲击系数的影响规律不可预测；桥面不平度是影响冲击系数的重要因素,桁梁桥关键截面冲击系数随桥面恶化显著增大,最大增幅约为400%；随着车重降低,桁梁桥关键截面冲击系数增大,最大增幅约为200%；随着混凝土填充系数的增大(下弦杆混凝土填充长度增加),由于桁梁桥下弦杆相对刚度提高,其冲击系数值略有增大；桁梁桥关键截面轴力冲击系数大于挠度冲击系数。在95%保证率下,该部分填充混凝土矩形钢管组合桁梁桥冲击系数统计值为0.223,小于美国规范、澳大利亚规范、英国规范和加拿大规范中的冲击系数取值,但大于中国规范中的冲击系数取值,应引起桥梁设计者的高度重视。

Research on Impact Coefficient of Partially Concrete-filled Rectangular Steel Tubular Composite Truss Bridge

In order to study the amplification effect of vehicle excitation force for partially concrete-filled rectangular steel tube composite truss bridge, a three-span continuous partially concrete-filled rectangular steel tube composite truss bridge was taken as the research object. The deflection impact coefficient and axial force impact coefficient of the truss bridge were obtained by the definition of bridge impact coefficient. The influence of different vehicle speed, bridge deck roughness, vehicle weight, concrete filling coefficient on the impact coefficient of truss bridge was compared and analyzed. The MATLAB software was used to test the goodness of fit of 867 impact coefficients, and the statistical value of impact coefficient of truss bridge under 95% guarantee rate was obtained. The results show that partial concrete filling can effectively reduce the dynamic response of the lower chord of the rectangular steel tube composite truss bridge, but it does not reduce the dynamic amplification effect of the truss bridge under moving load. The influence of vehicle speed on impact coefficient of truss bridge is unpredictable. The bridge deck roughness is an important factor affecting the impact coefficient. The impact coefficients of key sections of the truss bridge increase significantly with the deterioration of the bridge deck, and the maximum increase is about 400%. With the decrease of vehicle weight, the impact coefficients of key sections of truss bridge increase, and the maximum increase is about 200%. With the increase of concrete filling coefficient, the impact coefficients of key sections of truss bridge increase slightly due to the increase of relative stiffness of lower chords of truss bridge. The axial force impact coefficients of key sections of truss bridge are greater than the deflection impact coefficients. Under the 95% guarantee rate, the statistical value of the impact coefficient of the partially concrete-filled rectangular steel tube composite truss bridge is 0.223, which is less than the impact coefficient value in American code, Australian code, British code and Canadian code, but greater than the impact coefficient value in Chinese code, which should be highly valued by bridge designers.