初始弯曲应力对冻融-碳化后钢筋混凝土梁承载力影响分析  

Analysis on influence of initial bending stress on bearing capacity of reinforced concrete beam after freeze-thaw carbonization

作　　者：胡大琳[1] 徐怀存 张航 陈峰[1] 查斌 HU Da-lin;XU Huai-cun;ZHANG Hang;CHEN Feng;ZHA Bin(School of Highway,Chang'an University,Xi'an 710064,Shaanxi,China;CCCC First Highway Consultants Co.,Ld.,Xi'an 710075,Shaanxi,China;State Key Laboratory of Safety and Health for In-service Long Span Bridges,Nanjing 211112,Jiangsu,China)

机构地区：[1]长安大学公路学院,陕西西安710064 [2]中交第一公路勘察设计研究院有限公司,陕西西安710075 [3]在役长大桥梁安全与健康国家重点实验室,江苏南京211112

出　　处：《长安大学学报（自然科学版）》2020年第5期38-47,共10页Journal of Chang’an University(Natural Science Edition)

基　　金：交通运输部应用基础研究项目(2013319812100);国家自然科学基金项目(51808048)。

摘　　要：为研究弯曲应力对冻融-碳化作用下在役钢筋混凝土梁桥承载力的影响,设计并制作了8片钢筋混凝土梁,采用自行设计的持荷装置对试验梁进行弯曲应力加载,并置于环境实验室中进行冻融-碳化耦合腐蚀,再对腐蚀后的试验梁进行荷载试验。对不同弯曲应力水平下的钢筋混凝土试验梁进行裂缝分析、应变特征分析和承载力的研究,并建立有限元数值模型,将其与试验结果进行对比分析。研究结果表明:随着初始弯曲应力水平的增加,2组试验梁破坏形态由1条主裂缝变为多条裂缝并存,并且延性明显降低;跨中压应变斜率及拉应变均逐渐增大,跨中应变分布已经不能完全符合平截面假定。根据试验梁的荷载位移曲线可知,混凝土强度等级的提高明显提升了试验梁抗冻融-碳化腐蚀的能力;弯曲应力水平增加会导致试验梁的承载力(屈服弯矩、极限弯矩)降低,且其大致呈线性关系。通过ANSYS有限元数值模拟与试验梁的承载力实测数据对比,归纳出冻融-碳化作用下不同弯曲应力水平对钢筋混凝土梁材料本构的修正系数φ,可为严寒区在役钢筋混凝土桥梁承载力衰减分析评估提供参考和简化分析方法。In order to research the influence of bending stress on the bearing capacity of existing reinforced concrete bridges under the interaction of freeze-thaw and carbonization,8 reinforced concrete beams were designed and made,bending stress of the test beams was loaded with a self-designed load holding device,the test beams were placed in the environmental laboratory for freeze-thaw carbonization coupling corrosion,then load test was carried out on the test beams after the corrosion.The fracture analysis,strain characteristic analysis and bearing capacity of test beams at different bending stress levels were studied.The finite element numerical model of the reinforced concrete test beam was established,and analysis results were compared with that of experiment.The results show that with the increase of initial bending stress level of the two groups of test beams,the failure pattern of the test beams will change from one main crack to multiple cracks,ductility of the test beam is significantly reduced.The compressive strain slope and tensile strain values of the mid-span will gradually increase,the mid-span strain distribution no longer fully conforms to plane cross-section assumption.By analyzing the load-displacement curve of the test beam,when increase of concrete strength grade,the ability of the test beam to resist corrosion of carbonization and freeze-thaw improves significantly.As the bending stress level increases,the bearing capacity(yield bending moment,ultimate bending moment)of the test beams will decrease and will be approximately linear.Through the comparative analysis between ANSYS finite element numerical simulation and the measured data of bearing capacity of the test beams,modified coefficientφof the constitutive behaviors of reinforced concrete beams under different bending stress levels after the interaction of freeze-thaw and carbonization is concluded.The results of the test and numerical analysis can provide a reference and a simplified analysis method for the bearing capacity analysis and eva

关 键 词：桥梁工程 承载力 荷载试验 钢筋混凝土梁 弯曲应力 有限元仿真 

分 类 号：U445.73[建筑科学—桥梁与隧道工程]