摘要
移动车辆作用下桥梁荷载效应和动力放大系数同时取最大值的概率很低,重量较轻的单个车辆荷载行驶过桥时即使产生较大的动力放大系数也不具参考性。准确获取反映桥梁结构实际状态的动力特征参数,可指导优化桥梁设计阶段动荷载系数选取,同时还可为桥梁运维阶段策略实施提供数据支撑。提出桥梁动力放大系数合理值(Reasonable Dynamic Amplification Factor,RDAF)的概念并定义其计算方法。通过获取与设计荷载相当的多车辆荷载任意行车工况下桥梁动、静力响应,将一系列多车辆荷载作用下最大动力响应和静力响应之比定义为桥梁RDAF。以简支梁桥为例,从准静态响应趋势、动力响应项、不平顺附加项等角度推导移动车辆荷载作用下桥梁动力响应近似解析解。结合数值算例,计算分析既有桥梁的RDAF,并从荷载等级、行车速度和桥面平顺性等方面进行影响因素研究。研究结果表明:桥梁RDAF主要受桥面平顺性、桥梁限行速度等因素影响;平顺性较好情况下的桥梁RDAF与设计规范规定的动力放大系数值基本一致;平顺性变差时则需通过限速或限载至合理范围来保证动态荷载效应在允许范围内。研究表明桥梁RDAF是桥梁状态的固有特征参数,桥梁结构RDAF反映其实际运营状态,该指标参数可为桥梁限载、限速、路面铺设等管养措施的实施提供指导和参考。
The probability of the scenario that the maximum quasi-static response and dynamic effect of bridge under moving vehicle load occurs at the same time is extremely low.Meanwhile,the relatively greater dynamic amplification factor obtained when a single low-self-weight vehicle passes the bridge is not representative.As such,acquiring the accurate actual dynamic characteristic parameters of bridges can lead to an optimized dynamic load coefficient in the bridge design,and provide data support for the implementation of bridge operation and the maintenance.This paper proposed the concept and calculation method of the reasonable value of bridge dynamic amplification factor(RDAF).By obtaining the dynamic and static response of the bridge under arbitrary multi-vehicle load conditions that equivalent to the design load,the ratio of the maximum dynamic response to the maximum static response was defined as the bridge RDAF.Taking the simply supported bridge as an example,the approximate dynamic response under the action of moving vehicles was derived from the quasi-static response trend,dynamic responses and additional item caused by irregularity.Combined with numerical examples,this paper first calculated the RDAF of the existing bridges.And then,a parametric study considering influencing factors such as the load level,vehicle speed and pavement irregularity was conducted.The results show that the RDAF of the bridge structure is mainly influenced by the pavement irregularity,the speed limit of the bridge,etc.The RDAF of the bridge with better pavement regularity is generally consistent with the dynamic amplification factor specified in the design specifications.When the pavement regularity deteriorates,it is necessary to lower the allowable vehicle speed or load to a reasonable range to ensure that the dynamic effect is within the range as specified.Results of this paper also show that bridge RDAF which reflects the actual bridge operation state,is the inherent characteristic parameters of bridge structure.This parameter can assist the implementation of bridge load limit,speed limit,pavement construction and other bridge maintenance measures.
作者
肖柏军
赵雨森
王宁波
XIAO Baijun;ZHAO Yusen;WANG Ningbo(School of Civil Engineering,Central South University,Changsha 410075,China)
出处
《铁道科学与工程学报》
CAS
CSCD
北大核心
2022年第1期171-180,共10页
Journal of Railway Science and Engineering
基金
国家自然科学基金资助项目(52078486)。
关键词
公路桥梁
动力放大系数
合理值
桥梁影响线
桥面不平顺
roadway bridge
dynamic amplification factor
reasonable value
bridge influence line
surface irregularity
