环境侵蚀与荷载耦合作用下钢混组合桩抗震性能研究

发布时间：2018-05-30 18:41

本文选题：钢混组合桩基础 + 抗震性能　；参考：《长安大学》2015年硕士论文

【摘要】：钢混组合桩基础在我国大跨径桥梁的设计和建设中得到了广泛应用,尽管该基础形式在适应自然建设条件、缩短施工周期、降低节约造价等方面有自身优点,但是地震灾害调查表明,它仍然是桥梁结构体系中的地震易损构件,且其工作环境通常为江水、海水等氯离子侵蚀环境,钢筋、混凝土以及包裹在桩身外部的钢护筒受环境侵蚀的问题比较突出,且侵蚀的速度与结构受荷大小有关。钢混组合桩受侵蚀后,材料性能会发生显著变化结构体系的抗震性能能否达到最初的设计功能并满足当前的使用要求?这已成为正确评价此类结构抗震能力亟待解决的一个问题,由于目前这方面的研究成果较少,因此工程师在解决钢混组合桩结构受到环境侵蚀和荷载耦合作用下的抗震性能评估问题时所能参考和借鉴的成果为数不多,为此本文对钢混组合桩基础在侵蚀环境中的抗震性能进行了理论和试验研究,主要内容如下:(1)作者在查阅大量文献的基础上,对钢混组合桩基础在我国桥梁工程领域的应用现状、桩基础的震害调查情况、钢筋和混凝土的侵蚀机理、侵蚀影响因素以及受侵蚀后的力学性能变化规律进行了归纳总结;(2)在总结钢筋和混凝土受侵蚀后材料性能变化规律的基础上实施了不同时长和不同受荷状态下的钢筋锈蚀试验,通过模拟钢筋在侵蚀环境中施加不同加荷量级和不同侵蚀时长的锈蚀试验来测试钢筋性能的变化情况,并对实验数据近似拟合出了关于钢筋屈服强度sdf、钢筋极限强度yf、质量损失率w(%)、伸长率?(%)和侵蚀时间t、荷载量级?的双参数近似公式,上述工作对仿真分析研究侵蚀环境中钢筋在荷载和时间耦合作用时钢护筒材料参数取值有一定的参考作用;(3)通过查阅文献资料及结合钢筋锈蚀试验结论,对不同锈蚀工况材料参数取值进行确定,并利用OpenSEES有限元平台建立了弹塑性纤维单元计算模型,对该模型进行Pushover分析和地震波响应时程分析,通过对比材料退化前后钢混组合桩基础的能力曲线,对体系在受到不同侵蚀程度后的抗震性能进行评价;(4)通过查阅文献资料利用钢筋锈蚀速率研究理论对本文各试验工况锈蚀速率进行预测,并对考虑侵蚀环境中钢混组合桩受侵蚀后的承载力计算公式进行修正,为设计者合理考虑钢护筒对桩基承载力提供参考。
[Abstract]:The steel-concrete composite pile foundation has been widely used in the design and construction of long-span bridges in China, although the foundation has its own advantages in adapting to the natural construction conditions, shortening the construction period and reducing the cost. But the investigation of earthquake disaster shows that it is still the seismic vulnerable component in the bridge structure system, and its working environment is usually the environment of chloride ion erosion, such as river water, sea water and so on. The problem of environmental erosion of concrete and steel casing wrapped outside the pile is more serious, and the speed of erosion is related to the size of the structure. After the erosion of steel-concrete composite pile, the material performance will change significantly. Can the aseismic performance of the structural system reach the original design function and meet the current requirements? This has become an urgent problem to be solved in evaluating the aseismic capacity of such structures. Therefore, there are few achievements that engineers can refer to and use for reference in solving the problem of seismic performance evaluation of steel-concrete composite pile structure under environmental erosion and load coupling. Therefore, the seismic behavior of steel-concrete composite pile foundation in erosive environment is studied theoretically and experimentally in this paper. The main contents are as follows: (1) on the basis of consulting a large number of literatures, The present situation of application of steel-concrete composite pile foundation in the field of bridge engineering in China, the investigation of earthquake damage of pile foundation, the erosion mechanism of steel bar and concrete, The influence factors of erosion and the changing law of mechanical properties after erosion are summarized and summarized. The corrosion tests of steel bars under different loading conditions are carried out on the basis of summarizing the changing rules of material properties of steel bars and concrete after erosion. The performance of steel bars is tested by simulating corrosion tests with different loading orders and different corrosion time periods in the erosion environment. The experimental data are approximately fitted to the yield strength of steel bar SDF, the ultimate strength of steel bar yf, the loss rate of mass wand the elongation of the steel bar) and the erosion time t, the magnitude of the load? The above work can be used as a reference for the simulation analysis and study of the parameters of steel pipe material under the coupling of load and time in the erosive environment. (3) by consulting the literature data and combining with the conclusion of corrosion test of steel bar, The material parameters under different corrosion conditions are determined, and the elastic-plastic fiber element calculation model is established by using OpenSEES finite element platform. The Pushover analysis and seismic wave response time history analysis of the model are carried out. By comparing the capacity curves of steel-concrete pile foundation before and after material degradation, The aseismic performance of the system under different erosion degree is evaluated. The corrosion rate of each test condition is predicted by referring to the literature and using the theory of reinforcement corrosion rate research. The formula for calculating the bearing capacity of steel-concrete composite pile under erosion environment is revised, which provides a reference for designers to consider the bearing capacity of steel retaining tube on pile foundation reasonably.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U443.15

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