汽车制动作用下预应力混凝土简支梁桥的动力响应及冲击系数研究

Study of the Dynamic Responses and Impact Factors of Simply-supported Prestressed Concrete Girder Bridges Due to Vehicle Braking

基于三维车桥振动模型研究了汽车制动对桥梁的冲击作用.选用一辆典型三轴重车模型,获得了汽车制动时预应力混凝土简支梁桥的跨中动力响应及冲击系数.研究了刹车位置、减速度、初速度、路面平整度、桥跨长度等因素对动力冲击系数的影响,并将计算得到的动力冲击系数与中国规范进行了对比.结果表明,汽车刹车对桥梁的冲击效应随着制动力的增大而增大,并且在桥梁前半跨内刹车产生的动力冲击效应要大于在后半跨内刹车.同时,汽车制动时桥梁的动力响应及冲击系数均明显大于车辆匀速行驶的情况,且冲击系数可能超出规范值.

In this study,a three-dimensional vehicle-bridge coupled model was developed to study the dynamic impact of vehicle braking on bridges.The dynamic responses and impact factors of simply-supported prestressed con-crete girder bridges were obtained under the braking of a typical three-axle vehicle model.A parametric study was per-formed to investigate the effect of several important parameters,including the vehicle braking position,deceleration rate,initial vehicle speed,road surface condition and bridge span length,on the impact factors.In addition,a compar-ison was conducted between the calculated dynamic impact factors and those specified in the current Chinese bridge de-sign code.The results show that the impact of vehicle braking on bridges increases with the increase of braking force, and braking within the first half span causes greater impact than braking within the second half span.Furthermore, the dynamic responses and impact factors of bridges due to vehicle braking are notably greater than those due to the vehicles moving at constant speeds,and the impact factors may exceed those specified in the current Chinese bridge de-sign code.