曲线连续梁桥在车辆制动作用下的动力响应

以某一匝道公路曲线连续箱梁桥为例,分析了该类桥梁的空间车桥耦合振动问题。用ANSYS软件模拟梁桥,选用典型的三轴空间车辆模型,采用模态综合法编制公路曲线车桥耦合振动响应MATLAB程序,获得了车辆制动作用下曲线连续梁桥的动力响应及冲击系数,研究了初速度、制动位置、制动力上升时间、桥面平整度等参数对冲击系数的影响。结果表明:车辆制动时,主梁最大挠度、挠度和内力冲击系数没有随初速度的增大而单调递增或递减,但均明显大于车辆以相同初速度匀速行驶时的结果,且可能超过规范值。在桥前半跨内制动时,挠度和跨中剪力冲击系数大于在后半跨度内制动情况,同时,当车辆制动位置大于半跨且越靠近支点时,车辆制动时挠度和内力冲击系数越接近匀速时的结果。随着曲率半径的增大,桥梁的挠度、弯矩和扭矩冲击系数逐渐减小,而剪力冲击系数逐渐增大;弯桥的挠度、弯矩和扭矩冲击系数大于直线桥结果,紧急制动易于加剧桥梁的振动。

Dynamic response of curved continuous girder bridge under vehicle braking

The coupling vibration of space vehicle-bridge of this kind of bridge was analyzed basing on a curved continuous box girder bridge on an ramp.The ANSYS software was used to simulate the beam bridge, and the typical three-axis space vehicle model was selected.The dynamic response and impact of the curved continuous box girder bridge under the braking effect of the vehicle were obtained by the MATLAB program of the highway curve using the modal comprehensive method.And the influence of initial speed, braking position, braking rising time and bridge deck smoothness on dynamic impact coefficient was studied.The results showed that the maximum deflection, deflection and internal force impact coefficient of the main girder do not increase or decrease monotonously with the increase of initial speed, but they are obviously larger than the results when the vehicle runs at the same initial speed and may exceed the standard value.The impact coefficient of deflection and mid-span shear force in front half-span braking is greater than that in the back half-span braking.At the same time, when the braking position of the vehicle is greater than half-span and closer to the fulcrum, the impact coefficient of deflection and internal force is closer to the result of uniform speed braking.With the increase of curvature radius, the impact coefficient of deflection, bending moment and torsion of bridge decreases gradually, while the impact coefficient of shear force increases gradually.In addition, the impact coefficients of deflection, bending moment and torsion curved bridges are larger than those of straight bridges and emergency braking tends to aggravate bridge vibration.