预应力混凝土梁桥承载力退化研究

发布时间：2018-04-09 00:06

本文选题：预应力混凝土梁桥　切入点：承载力退化　出处：《郑州大学》2014年硕士论文

【摘要】：预应力混凝土梁桥面临着自身性能退化、交通量急速增长以及车辆超载超限等情况，不少桥梁出现了耐久性下降、承载力退化等问题。国内外学者已对混凝土碳化深度、氯离子侵蚀、普通钢筋锈蚀程度等方面开展了研究，取得了许多成果，但是针对高强度预应力混凝土结构的研究成果较少。因此，开展预应力混凝土梁桥承载力退化研究，具有十分重要的意义。本文以郑少高速公路连接线南水北调大桥辅线桥为依托工程，通过对比分析不同的混凝土碳化模型，并结合预应力混凝土梁桥的特点，选取了考虑混凝土的养护条件、掺合料的掺量以及环境条件影响、以“水灰比和水泥用量”为主要参数的混凝土碳化深度预测公式；提出了考虑多重因素影响的氯离子扩散系数模型；分别进行了混凝土碳化作用和除冰盐中氯离子侵蚀两种环境下的普通钢筋锈蚀和预应力钢绞线腐蚀的预测研究，给出了普通钢筋锈蚀和预应力钢绞线腐蚀的预测模型；分别选取主梁跨中截面和1/4处截面，对依托工程在混凝土碳化作用和除冰盐中氯离子侵蚀两种环境下设计基准期内的承载力进行了预测。本文完成的主要工作和所得结论： 1.对比分析了不同混凝土碳化深度预测模型，通过与快速碳化试验值、工程碳化深度实测值的比较，得出张誉模型和牛荻涛模型优于同类其它模型；综合考虑各影响因素后，对张誉模型进行了修正和验证，使修正后的张誉模型更适合预测河南省地域内的预应力混凝土梁桥的碳化深度。 2.归纳总结了影响氯离子扩散系数的主要因素，综合考虑水灰比、掺合料种类及含量、时间、温度、混凝土对氯离子的结合能力、混凝土材料自身劣化以及应力水平诸多因素的影响，提出了考虑多因素影响的氯离子扩散系数模型，并结合工程实例验证了该模型的实用性。 3.对比分析了碳化作用下的不同钢筋锈蚀模型，并给出了模型的使用建议；总结给出了氯离子侵蚀环境下的钢筋锈蚀模型；在相同条件下，氯离子侵蚀比混凝土碳化对钢筋锈蚀的危害要严重得多；对比分析了锈蚀钢筋强度退化系数和两类协同工作系数，给出了协同工作降低系数的适用情况。 4.结合先张法和后张法施工构件的各自特点，分别给出了采用先张法、后张法施工的预应力混凝土梁桥在混凝土碳化和除冰盐中氯离子侵蚀两种环境作用下的钢绞线腐蚀计算模型，选取了合适的腐蚀钢绞线有效截面积、强度以及与混凝土协同工作系数计算公式，依据规范，分别建立了锈蚀预应力混凝土梁抗弯承载力和斜截面抗剪承载力的计算方法。 5.对依托工程在混凝土碳化作用和除冰盐中氯离子侵蚀两种环境下设计基准期内的承载力进行了预测：不考虑施工因素和超载等导致混凝土开裂的情况，在混凝土碳化作用下，抗弯承载力保持较高水平，斜截面抗剪承载力有所退化但并不显著，承载力满足设计要求；除冰盐中氯离子侵蚀环境下，预应力钢绞线腐蚀发生尤其是钢绞线锈胀开裂后，抗弯承载力有一定程度退化，箍筋锈胀开裂后，，斜截面抗剪承载力有一定程度退化。
[Abstract]:The prestressed concrete beam bridge is facing its own performance degradation, the rapid growth of traffic volume and vehicle overload, many bridges durability decreased degradation capacity. Domestic and foreign scholars have been on the carbonation depth of concrete, chloride ion corrosion, general corrosion degree of reinforcing bar etc., made many achievements but according to the research results of high strength prestressed concrete structure is less. Therefore, to carry out the study on the degradation of prestressed concrete beam bridge bearing capacity, it has very important significance.
In this paper, Zheng Shao Expressway connecting line of South to north water diversion line bridge bridge project, through the comparative analysis of different concrete carbonation model, combined with the characteristics of prestressed concrete beam bridge, selected considering the concrete curing conditions, effects of admixture dosage and environmental conditions, the prediction formula of concrete carbonation depth with water cement ratio and the amount of cement as the main parameters of the proposed model; coefficient of chloride ion diffusion considering multiple factors were carried out; the role of concrete carbonation and the prediction of two kinds of environment of ordinary steel bar corrosion and corrosion of prestressed steel strand in ice and salt chloride, presented the prediction model of ordinary reinforced and prestressed steel corrosion corrosion; selected girder section and 1/4 cross section in, based on the engineering in the concrete carbonation and deicing salt chloride two ring The bearing capacity of the design reference period is predicted. The main work and conclusions completed in this paper are as follows:
1. comparative analysis of the different prediction models of concrete carbonation depth, with the rapid carbonization test value, compare the carbonation depth measured value, the Zhang Yu model and other Niu Ditao models is better than similar; considering all the factors, the Zhang Yu model was revised and verified, the modified model more Zhang Yu suitable for the carbonation depth of prestressed concrete beam bridge in Henan Province in the region.
2. summarizes the main factors influencing the chloride ion diffusion coefficient, considering the water cement ratio, admixture type and concentration, time, temperature, binding capacity of concrete to chloride ion, the effect of concrete material deterioration and stress level of many factors, put forward the coefficient model considering many factors influence the chloride ion diffusion and combined with the engineering examples to verify the practicability of the model.
3. comparative analysis of the different corrosion model of carbonation, and gives the suggestions of using the model is summarized.; corrosion model chlorideenvironment; under the same conditions, the erosion of chloride ions than harm concrete carbonation of steel corrosion is more serious; comparative analysis of the strength of corroded reinforcement and degradation coefficient two kinds of coordination coefficient, given the reduced coefficient for collaborative work.
4. combining the features of pretensioned and post tensioned members, the paper gives the pretensioning method, post tensioned prestressed concrete bridge in concrete carbonation and deicing salt chloride corrosion of two kinds of steel wire under the action of the environment model, selects the appropriate and effective section of corroded steel strands area, and concrete strength and coordination coefficient calculation formula are established according to the specification, the shear bearing capacity calculation method of the bearing capacity of inclined section and bending corrosion of prestressed concrete beam.
5. on the effect on the carbonation of concrete and in addition to predict the bearing capacity design reference period of two environmental ice salt chloride contamination: without considering the construction factors and overload lead to concrete cracking, in the role of the carbonation of concrete under bending, maintain a high level of bearing capacity, shear capacity the force has deteriorated but not significant, meet the design requirements of the bearing capacity; deicing salt in chloride environment, the corrosion of prestressed steel strand occurred especially steel wire cracking, bending bearing capacity with a certain degree of degradation, hoop rust expansion cracking, bearing capacity of a certain degree of degradation of shear.

【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U441;U448.35

【参考文献】