钢桁—混凝土T构组合桥梁温度效应影响分析

发布时间：2018-08-12 08:03

【摘要】：钢桁—混凝土T构组合结构桥梁是混凝土箱梁桥面板与钢桁架共同受力的一种新型组合结构，因其刚度大、结构自重低、整体稳定性好、抗震性能强和行车平顺等一系列优点，已在各国的公路和高速铁路中得到广泛应用。但是在日照或者气候变化的影响下，钢桁架和混凝土都会产生不同程度的温度应力和变形，因此很容易导致混凝土出现开裂的问题。从既有的研究来看，国内外桥梁专家学者针对混凝土箱梁桥的温度效应做了大量的研究工作，积累了许多宝贵的经验，但是对于钢桁—T构组合梁桥温度效应及开裂问题没有得到足够的重视。本文结合新建高速铁路大同至西安某黄河特大桥主跨部分单T刚构加劲钢桁组合结构实际工程，深入研究钢桁—T构组合梁桥温度场分布规律，完善温度效应理论计算和实桥测试研究，分析了钢桁—T构组合梁桥开裂机理，给出了裂缝控制措施。基于以上分析，本文在以往研究的基础上利用空间有限元软件对该单T刚构加劲钢桁组合桥梁进行计算分析，主要进行了以下工作： 1．通过对钢桁架结构日照温度场的监测以及气象资料的分析，得到了钢桁在日照作用下的温度分布规律和极端温度荷载分布情况。并根据温度分布规律，分析了钢桁架在日照影响、极端温度荷载、极端温度荷载与恒活载组合三种荷载工况。 2．建立某黄河特大桥主跨部分单T刚构加劲钢桁组合结构空间有限元模型，计算分析了钢桁架分别在三种工况下桥梁支座竖向反力、桁架应力及混凝土应力与位移变化规律。得出了在线性温度荷载作用下，支座竖向反力、桁架应力和混凝土应力均为线性变化；极端温度荷载作用下，，相互对立的钢桁架V型斜杆总是一边受拉一边受压，升温荷载作用使主梁上挠，降温荷载作用使主梁下挠；在极端温度荷载与恒活载组合作用下，掌握了桥梁最不利情况下的桁架应力以及混凝土主梁应力、挠度变化情况。 3．研究了钢桁—混凝土T构组合梁桥桁架与混凝土结合处的连接类型，得到了温度变化对桁架与混凝土连接处受力的影响机理。建立结合点三维实体有限元模型，计算分析了极端温度荷载作用和组合作用两种最不利情况，得到了此时全桥混凝土应力最大位置处结合点混凝土的应力以及裂缝情况。 4．本文根据计算结论结合相关文献，分析了钢桁—混凝土T构组合桥梁温度裂缝的特点以及成因，继而提出了钢桁—混凝土T构组合桥梁温度裂缝的防裂措施，用以指导这类桥梁的设计与施工。
[Abstract]:Steel truss-concrete T-structure composite structure bridge is a new type of composite structure with concrete box girder bridge slabs and steel truss. It has a series of advantages such as high stiffness, low deadweight, good overall stability, strong seismic performance and smooth running, etc. It has been widely used in highway and high-speed railway all over the world. However, under the influence of sunshine or climate change, both steel truss and concrete will produce different degrees of thermal stress and deformation, so it is easy to cause cracking of concrete. From the existing research, bridge experts and scholars at home and abroad have done a lot of research work on the temperature effect of concrete box girder bridge, and accumulated a lot of valuable experience. However, not enough attention has been paid to the temperature effect and cracking of steel truss-T composite girder bridge. In this paper, the temperature field distribution of steel truss composite girder bridge with steel truss is studied in combination with the practical engineering of single T rigid frame stiffened steel truss composite structure in the main span of a new high-speed railway from Datong to a certain Yellow River super large bridge in Xi'an. The theoretical calculation of temperature effect and the test of real bridge are improved. The cracking mechanism of steel truss-T composite beam bridge is analyzed and the crack control measures are given. Based on the above analysis, this paper uses the spatial finite element software to calculate and analyze the single T rigid frame stiffened steel truss composite bridge based on the previous research. The main work is as follows: 1. The temperature distribution and extreme temperature load distribution of steel truss under sunlight are obtained by monitoring the temperature field of steel truss structure and analyzing meteorological data. According to the temperature distribution, the influence of steel truss on the extreme temperature load is analyzed. Extreme temperature load and dead load combination. 2. A spatial finite element model of a single T rigid frame stiffened steel truss composite structure with main span of a Yellow River bridge is established. The vertical reaction force, truss stress and concrete stress and displacement of steel truss are calculated and analyzed under three working conditions. Under the action of linear temperature load, the vertical reaction force, truss stress and concrete stress of the bearing are all linearly changed, and under extreme temperature load, the V-shaped oblique bar of steel truss is always subjected to tension and compression at the same time. Under the combined action of extreme temperature load and dead load, the stress of truss and the stress of main beam of concrete under the most disadvantageous condition of bridge are grasped. 3. The connection type between truss and concrete of steel truss-concrete composite beam bridge is studied, and the influence mechanism of temperature change on the joint force between truss and concrete is obtained. The 3D solid finite element model of the junction point is established, and the two most disadvantageous cases of extreme temperature load and combination action are calculated and analyzed. At this time, the stress and crack of the concrete at the joint point at the maximum stress position of the whole bridge concrete are obtained. 4. According to the calculation conclusion, the paper combines the relevant literature, This paper analyzes the characteristics and causes of temperature cracks of steel truss-concrete T-structure composite bridges, and then puts forward the measures to prevent the temperature cracks of steel truss-concrete T-structure composite bridges, which can be used to guide the design and construction of this kind of bridges.
【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】：U441.5

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