【作者】 曾涛；

【导师】 方淑君； 盖青山；

【作者基本信息】 中南大学 ， 土木水利（专业学位）， 2023， 硕士

【摘要】 连续梁拱桥中,拱脚是保证梁拱组合受力的关键部位,是桥梁设计和施工建造需关注的重点之一。既有简支系杆拱桥和连续刚构拱桥研究表明,拱脚局部刚度对成桥状态下拱肋线形和吊索索力均有不同程度影响,数值仿真中应采用考虑拱脚等效刚度的计算模型。但该结论对于连续梁拱桥的适用性如何,还有待研究。本文以某在建(90+180+90)m大跨度连续梁拱桥为工程背景,采用数值仿真和现场实测相结合的方法,研究确定了该桥拱脚等效刚度合理取值,考察了拱脚等效刚度对不同施工阶段拱肋和吊索受力状态的影响,并在此基础上分析了拱脚局部受力状态。主要工作和成果如下:(1)针对本文所依托的大跨度连续梁拱桥,模拟全桥施工过程,完成了不同施工工况下的结构受力状态分析。结果表明:该桥施工过程中,主梁、拱肋的强度、刚度均满足设计要求,且有较大储备量;主梁最不利工况为拼装拱肋钢管阶段,最大压应力为-17.6MPa,出现在边跨距离主墩68.3m处的主梁截面下缘,最大竖向位移为-164.1mm,出现在中跨距主墩70.5m处;钢管混凝土拱肋最不利工况为吊索终张阶段,钢管最大压应力为-100.0MPa,出现在拱脚处下缘,拱肋最大竖向位移为-85.5mm,出现在拱顶。(2)基于位移等效原则,确定了本文所依托的大跨度连续梁拱桥的拱脚等效刚度,考察了拱脚等效刚度对拱肋施工过程受力状态的影响,完成了拱肋施工过程的现场监测,并将监测结果与计算结果进行了对比分析。结果表明:考虑拱脚等效刚度计算所得拱肋施工过程中的线形和应力与现场监测结果吻合良好,验证了本文所确定的拱脚等效刚度取值的合理性;与不考虑拱脚等效刚度相比,考虑拱脚等效刚度后,拱肋最大挠度计算值与实测值的误差由15%降低到7%,拱肋最大应力计算值与实测值误差由18%降低到8%,施工控制精度大幅提高。(3)基于上述结果,结合现场监测,分析了拱脚局部受力状态,同时考察了拱脚区域拱肋管内混凝土灌注方案对拱脚局部受力状态的影响。结果表明:最不利工况下,考虑拱脚等效刚度所得精细化仿真分析结果与现场监测结果吻合较好,拱脚总体应力水平较低,强度储备充足。拱脚区域管内混凝土灌注方案对拱脚局部受力状态影响较大。本文所提出的三种灌注方案中,支架卸载前灌注拱脚区域管内混凝土所引起的拱脚局部应力水平相对较低,该方案为实桥施工所采纳。(4)分别针对拱肋施工过程、成桥及运营阶段,完成了本文所依托大跨度连续梁拱桥的稳定性分析,考察了拱脚等效刚度对拱肋稳定性的影响。结果表明:考虑拱脚等效刚度后,计算所得拱肋施工完成和成桥阶段的拱肋一阶稳定系数分别为11.2和7.0,相比于不考虑拱脚等效刚度时均提高了13%以上。本文部分成果已为所依托大跨度连续梁拱桥施工所采纳,效果良好。图92幅,表40个,参考文献80篇更多还原

【Abstract】 In continuous girder arch composite bridges,the arch foot is the key part to ensure the force of the girder arch combination,and it is one of the key points to be paid attention to in bridge design and construction.Studies on the existing simply supported tied arch Bridges and continuous rigid arch Bridges show that the local stiffness of the arch foot has different effects on the arch rib alignment and cable force under the completion state of the bridge.The calculation model considering the equivalent stiffness of the arch foot should be adopted in the numerical simulation.However,the applicability of this conclusion to continuous girder arch composite bridges remains to be verified.Based on the engineering background of a(90+180+90)m large-span continuous girder arch composite bridge,this thesis studied and determined the reasonable value of arch foot equivalent stiffness by combining numerical simulation with field measurement,investigated the influence of arch foot equivalent stiffness on the stress state of arch rib and sling in different construction stages,and analyzed the local stress state of the arch foot on this basis.The main work and achievements are as follows:(1)For the long-span continuous girder arch bridge relied on in this thesis,the construction process of the whole bridge is simulated,and the structural stress state analysis under different construction conditions is completed.The results show that the strength and stiffness of the main girder and arch rib meet the design requirements,and there is a large reserve.The most unfavorable condition of the main girder is the stage of assembling arch rib-steel pipe.The maximum compressive stress is-17.6MPa,which occurs at the lower edge of the main girder section at a distance of 68.3m from the main pier with the side span.The maximum vertical displacement is-164.1mm,which occurs at a distance of 70.5m from the main pier with the middle span.The most unfavorable condition of concrete-filled steel tube arch rib is the final stretch stage of the sling.The maximum compressive stress of the steel tube is-100.0MPa and appears at the lower edge of the arch foot,while the maximum vertical displacement of the arch rib is-85.5mm and appears at the arch top.(2)Based on the displacement equivalent principle,the equivalent stiffness of the arch foot of the long-span continuous girder arch composite bridge relied on in this thesis is determined,and the influence of the equivalent stiffness of the arch foot on the stress state of arch rib construction process is investigated.The field monitoring of the arch rib construction process is completed,and the monitoring results are compared with the calculated results.The results show that the linear shape and stress obtained by considering the equivalent stiffness of the arch foot are in good agreement with the field monitoring results,which verifies the rationality of the equivalent stiffness of the arch foot determined in this thesis.Compared with no consideration of the equivalent stiffness of the arch foot,the error between the calculated maximum deflection of the arch rib and the measured value decreases from 15% to 7%,and the error between the calculated maximum stress of the arch rib and the measured value decreases from 18% to 8% after considering the equivalent stiffness of arch foot.The construction control precision is greatly improved.(3)Based on the above results,combined with field monitoring,analyzed the local stress state of the arch foot,and investigated the influence of the concrete filling scheme in the arch rib area on the local stress state of the arch foot.The results show that: under the most unfavorable conditions,the results of fine simulation analysis considering the equivalent stiffness of the arch foot agree well with the field monitoring results,the overall stress level of the arch foot is low,and the strength reserve is sufficient.The concrete filling scheme in the arch foot area has a great influence on the local stress state of the arch foot.Among the three grouting schemes proposed in this thesis,the local stress level of the arch foot caused by the concrete in the arch foot area before the support unloading is relatively low,and this scheme is adopted by the construction of the real bridge.(4)The stability analysis of the long-span continuous girder arch bridge based on the arch rib construction process and the bridge operation stage was completed respectively,and the influence of equivalent stiffness of the arch foot on the arch rib stability was investigated.The results show that after considering the equivalent stiffness of the arch foot,the first-order stability coefficients of the arch ribs after the completion of the construction and the finished stage of the bridge;are 11.2 and 7.0,respectively,which are increased by more than 13 % compared with those without considering the equivalent stiffness of the arch foot.Some of the results of this thesis have been adopted by the construction of a long-span continuous girder arch composite bridge with good results.更多还原