随机振动下多跨弹性支撑梁桥的冲击系数分析

摘要

Based on random vibration theories and orthogonal test design,impact coefficients of a three-span elastically supported bridge and their influence factors were studied.The dynamic random responses of the bridge were solved using the pseudo-excitation method (PEM)under the actions of vehicles and bridge surface roughness.Based on the 3σstandard deviation rule,the random responses of the bridge deflection were converted from statistical results into a deterministic value field.Then the impact coefficients of the bridge were calculated.In order to investigate the influence laws and significance of bridge length,bridge stiffness,bridge surface roughness,vehicle velocity,vehicle weight and vehicle wheelbase on the impact coefficients at different positions of the bridge,an orthogonal test for influence factors on the bridge impact coefficients was designed.The results showed that the new method is accurate and can efficiently overcome the computation difficulties brought by the multi-factors orthogonal test;the differences of the deflection impact at different positions of the bridge are larger,they increase with increase in the level of the bridge surface roughness;the most significant influence factor is bridge surface roughness,followed by bridge length and vehicle velocity.%基于随机振动理论和正交试验设计，研究了三跨弹性支撑梁桥的冲击系数及其影响因素。采用虚拟激励法求解桥梁在车辆和桥面不平顺作用下的随机响应，根据三倍标准差准则将桥梁挠度随机响应由统计结果转化为确定性值域，进而求得桥梁冲击系数。通过设计桥梁冲击系数影响因素的正交试验，研究了桥梁长度、桥梁刚度、桥面不平顺、车速、车体质量和车辆轴距对桥梁不同部位的冲击系数的影响规律及显著性。计算结果表明：算法高效、精确，有效克服多因素正交试验带来的庞大计算困难；桥梁不同部位的挠度冲击系数差异较大，且随着桥面不平顺等级的提高而增大；与其他因素相比，对冲击系数影响最为显著的是桥面不平顺，其次为桥梁长度和车速。