【作者】 张弘；

【导师】 肖林； 卫星；

【作者基本信息】 西南交通大学 ， 建筑与土木工程（专业学位）， 2021， 硕士

【摘要】 钢-混凝土组合梁桥负弯矩区在荷载下会产生钢梁受压、混凝土桥面板受拉的不利情况,混凝土桥面板受拉开裂会降低组合梁的刚度与耐久性,在不利环境下易导致氯离子侵蚀,进一步降低其疲劳性能。本文一方面从设计角度出发,对各负弯矩区阻裂方案进行参数化分析;另一方面从运营角度出发,展开腐蚀效应下剪力键耐久性劣化研究。主要内容包括以下几个方面:(1)采用有限元软件ABAQUS对支点顶升、跨中压重、预应力张拉、刚度滞后剪力键、UHPC复合层5种负弯矩区阻裂方法共计23种方案进行阻裂效果分析。选取裂缝宽度、经济性等指标,基于模糊数学综合评价方法,对各方案进行评价进而选取最优方案,结果显示顶升35cm为最优方案。(2)对带裂缝的C50、ECC、UHPC组合梁试件进行6个月的浸泡试验,研究带裂缝状态下栓钉连接件的氯离子侵蚀路径,比较了三种材料抗氯离子侵蚀性能。结果表明:在带裂缝时,C50试件中氯离子更易从混凝土表面侵入,UHPC抗氯离子侵蚀能力最强。考虑最不利侵蚀路径,对栓钉连接件根部预置腐蚀坑初始缺陷,与未预置缺陷试件进行对比,对4个推出试件进行了静力加载,结果表明预置腐蚀坑对栓钉连接件承载力无明显影响,但造成其滑移量增大。将有限元分析结果与试验进行对比,验证了数值模拟的可靠性。(3)为研究腐蚀效应下栓钉连接件的疲劳性能,进行了7个推出试件的疲劳加载试验,采用通电加速锈蚀法对其中3个试件进行腐蚀疲劳加载。以疲劳寿命、残余滑移、动态滑移、剪力键刚度作为损伤变量,分析了腐蚀耦合效应下剪力键的疲劳性能劣化机制,结果表明,腐蚀耦合效应主要影响疲劳损伤发展阶段,造成疲劳寿命、刚度降低,其降低程度与腐蚀速率有关。(4)基于剪切破坏的开裂模式,结合断裂力学建立了腐蚀疲劳寿命预测模型,分析栓钉连接件的疲劳裂纹扩展路径,采用FRANC3D及MATLAB对试验进行了验证,理论值与试验值吻合较好,证明了该预测模型的可行性及有效性。更多还原

【Abstract】 When the composite girder is subjected to negative moment,the steel girder suffers compression while the concrete deck is subjected to tension.,which may cause tension cracks and weaken the stiffness and durability of the composite beam.In the adverse circumstance,the girder is vulnerable to chloride ion erosion and its fatigue performance is prone to be reduced.In the perspective of design,parametric analysis under negative bending moment for anti-crack schemes were conducted.Besides,in the perspective of operation,the research on the durability of deteriorated shear studs suffering corrosion was studied.The main contents include the following aspects:(1)With the finite element software ABAQUS,23 schemes are carried out to assess the effect of crack resistance based on 5 crack arresting methods including fulcrum jacking,midspan weight,pre-stressed tension,stiffness-lag shear key,and UHPC composite layer.Moreover,the crack width,economy and other indicators were considered as the crucial factors to evaluate each plan according to the fuzzy mathematics comprehensive evaluation method.The results show that 35 cm jacking is the best scheme.(2)Specimens of C50,ECC and UHPC composite beams with cracks were soaked for 6months to study the chloride ion erosion path of stud connectors,and the ability of erosion resistance of the three materials was compared.The results indicate that chloride ion in C50 specimen is more likely to invade from the concrete surface while UHPC has the strongest ability to resist chloride ion erosion.Secondly,considering the most unfavorable corrosion path,the corrosion pits are preset at the roots of stud to compare those without defects.Then four pushout specimens were loaded under static load.It can be seen that the preset corrosion pits have no obvious influence on the bearing capacity of shear connectors,but cause the increase of slip.The reliability of the numerical simulation is verified by comparing the finite element analysis results with the test results.(3)In order to study the fatigue performance of studs under corrosion,fatigue tests of seven push out specimens were carried out,and three of them were subjected to fatigue load coupled with electrical accelerated corrosion method.In detail,fatigue life,residual slip,dynamic slip and shear stiffness were utilized as damage variables to analyze the deterioration mechanics of shear studs under the corrosion-fatigue condition.The results show that coupling effect leads to the reduction of fatigue life and stiffness,and mainly affects the development stage of fatigue damage,which is related to corrosion rate.(4)The corrosion-fatigue life prediction model was established considering both shear cracking failure mode and fracture mechanics.The fatigue crack growth path of shear connectors was studied.the numerical model with FRANC3 D and MATLAB was verified by the test resuls.The results show that the theoretical values are in good agreement with the test values,which proves the feasibility and rationality of the prediction model.更多还原