公铁两用桥公路组合桥面板车辆荷载试验  

Live Load Testing on Highway Composite Deck of Rail-cum-road Bridge

作　　者：陈华婷[1] 李德旺 张文学[1] 谢益平 CHEN Hua-ting;LI De-wang;ZHANG Wen-xue;XIE Yi-ping(Faculty of Urban Construction,Beijing University of Technology,Beijing 100124,China;The 7th Engineering Co.Ltd.,China Railway 12th Bureau Group,Changsha 410004,Hunan,China)

机构地区：[1]北京工业大学城市建设学部,北京100124 [2]中铁十二局集团第七工程有限公司,湖南长沙410004

出　　处：《中国公路学报》2023年第3期211-224,共14页China Journal of Highway and Transport

基　　金：国家自然科学基金项目(52278137)。

摘　　要：公路桥面板直接承受反复车轮荷载,活载效应大,疲劳破坏风险大,已成为桥梁工程领域不可忽视的问题。为研究新型平钢板-PBL组合桥面板的初始应力状态和长期车辆荷载作用下的活载应力响应,以某新建公铁两用钢桁梁桥为工程背景,利用3轴施工车辆进行单车静载、单车动载和双车并行动载试验,通过预埋钢弦应变计和电阻应变片测量桥梁跨中截面和支墩截面的应变,并建立桥梁有限元模型分析桥面板在各种工况下的受力。研究结果表明:桥梁服役之前跨中截面和支墩截面桥面板分别处于受压和受拉的初始应力状态,支墩截面即使采用分段浇筑拉应变仍达101.8×10^(-6),存在较大的开裂风险;车辆荷载在桥面板大部分部位产生附加压应力,但在主桁附近横桥向产生附加拉应力,车辆长期作用下主桁附近桥面板有纵向开裂风险;桥面板各测点的影响线长度较短,大多为20 m左右,小于2个节间长度,试验车辆每次通过产生1个较大的应力循环;活载引起的实测应变幅值最大为34.6×10^(-6),考虑弯曲应变沿板厚的分布梯度,相应部位桥面板顶、底面的最大应变幅值为51.9×10^(-6),有可能引起疲劳失效;有限元模型得到的主桁处桥面板应力分布规律与实测结果总体吻合较好,表明模型可用于后续疲劳应力分析。研究结果可为同类型桥梁组合桥面板的评估与养护提供数据支撑和参考。Highway bridge decks are susceptible to fatigue failure under direct and repetitive wheel loading,and significant live load effects have caused increasing concerns in bridge engineering.We used a newly constructed rail-cum-road steel truss bridge as a case study to study the initial stress state and stress response in a steel-concrete composite bridge deck under a long-term vehicular live load.Static and dynamic load tests with a single truck passing the bridge deck,as well as dynamic load cases in which two trucks were driving on the deck side by side,were performed.The strains at the midspan and pier sections were measured using embedded vibrating chord and resistance strain gauges before concrete placement.We then established a finite element model of the bridge to analyze the structural behavior of the bridge deck under various loading cases of the field test.The measured strain results showed that the initial stress states of the concrete deck at the midspan and pier sections were compression and tension,respectively,before bridge service.The tensile strain at the pier section reached 101.8 micro strains even after staged construction,indicating a cracking risk.The testing vehicle caused additional compression stress for the majority of the bridge deck.However,the live load stress in the transverse direction near the main truss girder was tensile,causing it to experience repetitive live load stress and longitudinal cracking risk.Because the length of the influence line for all measuring points was approximately 20 m(less than two truss panels long),the testing truck generated one major stress cycle for each passing.The measured strain amplitude caused by the live load reached a maximum of 34.6 micro strains.Because the bending strain exhibited a strain gradient along the deck depth,the most significant strain amplitude on the top or bottom surface of the deck was 51.9 micro strains,triggering fatigue failure of the composite deck.The stress distribution from the finite element analysis coincided well with th

关 键 词：桥梁工程 公铁两用桥 桥梁荷载试验 组合桥面板 初始应力状态 活载应变幅值 

分 类 号：U448.121[建筑科学—桥梁与隧道工程]