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火灾全过程多梁式预应力混凝土T型梁桥整体抗火性能研究

发布时间:2018-02-01 06:49

  本文关键词: 多梁式预应力混凝土T梁桥 有限元 火灾 结构抗火性能 出处:《长安大学》2014年硕士论文 论文类型:学位论文


【摘要】:我国江河、湖泊、海湾众多,随着我国交通建设的快速发展,桥梁建设日新月异。桥梁上通行的大货车、油罐车、桥下通行的油轮,,均是潜在的火源,这些交通工具,尤其是油罐车在桥上或油轮在桥下发生事故失火,会对桥梁结构的安全造成极大的威胁。目前,我国桥梁结构的抗火性能研究刚刚开始,故极有必要大力开展桥梁结构的抗火研究,建立桥梁抗火设计实用规范。 本文以交通运输部建设科技项目“火灾下桥梁结构灾变机理及安全性评价与加固技术研究(2011318812970)”之专题3—“火荷载作用下具有砼桥面的大型梁桥结构影响参数研究”为依托,基于中央高校基金项目(CHD2011TD010)的部分研究内容,针对多梁式预应力混凝土T型梁桥结构整体抗火性能,建立了火灾温升模式,并设定了火灾场景,综合各材料特性和温升曲线,研究了桥下不同梁肋组合火灾模式下多梁式预应力混凝土T型梁桥空间变形、应力分布状态,揭示了火灾全过程多梁式预应力混凝土T型梁桥结构的整体抗火性能。 本文完成的主要研究工作内容如下: (1)研究了热力学传导矩阵和边界条件,给出了有限元求解温度场的基本方法和步骤;分析了HCM火灾温升曲线,建立了桥下火灾模式,设定火灾场景;研究了适用于预应力混凝土桥梁的材料热力学特性。 (2)研究了多梁式预应力混凝土T型梁桥桥下不同梁肋受火模式,分析了此模式下多梁式预应力混凝土T型梁桥相对应各片梁截面温度场分布及测点温度时程变化规律,分析了桥下火灾模式下多梁式预应力混凝土T型梁桥的空间应力时程分布状态,揭示了桥下对称火灾模式下多梁式预应力混凝土T型梁桥顶板的剪力滞空间分布规律。 (3)研究了桥下HCM火灾模式下多梁式预应力混凝土T型梁桥跨中断面梁肋及顶板横桥向挠度在延火前期和延火后期自重荷载作用下的变化特征,分析了顶板与梁肋的变形同步状态下的变形差异性,继而揭示了横截面的空间变形规律建立了不同梁肋组合火灾模式下梁肋的变形包络区域。
[Abstract]:There are many rivers, lakes and bays in our country. With the rapid development of traffic construction in our country, bridge construction is changing with each passing day. The large trucks, oil tankers and oil tankers passing under the bridge are all potential sources of fire. These vehicles, especially oil tankers on the bridge or oil tankers under the bridge fire accident, will pose a great threat to the safety of the bridge structure. At present, the fire resistance of bridge structures in China has just begun. Therefore, it is necessary to make great efforts to study the fire resistance of bridge structure and establish the practical code for the design of bridge fire resistance. In this paper, the disaster mechanism, safety evaluation and reinforcement technology of bridge structure under fire are studied in the construction of science and technology project of Ministry of Communications and Transport. Subject 3- "study on the structural parameters of large beam bridges with concrete deck under fire load". Based on the research of CHD2011TD010), the fire temperature rise mode of multi-beam prestressed concrete T-beam bridge structure is established. The fire scene was set, and the spatial deformation and stress distribution of multi-beam prestressed concrete T-beam bridge under different beam and rib combination fire mode were studied by synthesizing the characteristics of each material and temperature rise curve. The whole fire resistance of multi-beam prestressed concrete T-beam bridge is revealed. The main contents of this paper are as follows: 1) the thermodynamic conduction matrix and boundary conditions are studied, and the basic methods and steps for solving the temperature field by finite element method are given. The HCM fire temperature rise curve is analyzed, the fire mode under the bridge is established, and the fire scene is set up. The thermodynamic properties of materials suitable for prestressed concrete bridges are studied. The fire modes of different beam ribs under multi-beam prestressed concrete T-beam bridge are studied. In this model, the temperature field distribution of each beam section and the change law of temperature history of the measuring point are analyzed in the multi-beam prestressed concrete T-beam bridge corresponding to each section of the beam. The spatial stress time-history distribution of multi-beam prestressed concrete T-beam bridge under fire mode is analyzed. The spatial distribution of shear lag of the roof of multi-beam prestressed concrete T-beam bridge under symmetrical fire mode under bridge is revealed. In this paper, the variation characteristics of beam rib and roof transverse deflection of multi-beam prestressed concrete T-beam bridge under HCM fire mode are studied under the load of deadweight load before and after fire. The difference of deformation between roof and beam rib is analyzed, and the deformation envelope region of beam rib under different beam rib combination fire mode is established by revealing the spatial deformation law of cross section.
【学位授予单位】:长安大学
【学位级别】:硕士
【学位授予年份】:2014
【分类号】:U448.35

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