预应力混凝土曲线梁结构分析及病害防治

发布时间：2018-10-18 18:36

【摘要】：随着我国城市轨道交通事业的迅速发展,预应力混凝土曲线梁桥得到了越来越多的应用。曲线梁桥是复杂的空间受力结构,“弯扭耦合”是其最显著的受力特性。论文基于曲线桥的基本理论和有限元法,以北京地铁十四号线跨丰沙铁路桥为依托,详细分析了预应力混凝土曲线梁的受力特点,总结了曲线半径对曲梁力学行为的影响；针对曲线梁桥在施工和运营中常见的病害,着重研究了预应力荷载、温度荷载对曲梁的作用效应,分析了腹板钢束侧崩、主梁“爬移”、支座脱空等病害的产生原因,提出了一些防治措施。研究表明：在平面外竖向荷载作用下,即使是对称荷载,曲梁内也会产生较大的扭转力矩,发生相应的扭转变形。这种扭转作用使得曲梁内外两侧受力不均,主要表现为梁体内、外两侧的应力差异和抗扭双支座中内、外侧支座的反力差别。随着半径的减小,曲梁的扭转力矩增大,梁体内外两侧的受力越不均匀,扭转变形也更为剧烈。因此在曲线梁桥设计中,在满足其他要求的前提下,应尽可能选用较大的曲线半径。当曲线半径很小或张拉力很大时,预应力的径向水平分布力容易造成施工时腹板钢束的侧向崩出,对此可采用预应力钢束外移、增设防崩钢筋、合理设置横隔板、进行腹板防崩验算等方法,从设计上防止此类病害的发生。预应力产生的扭转作用和温度荷载也是造成曲梁“爬移”、支座脱空的重要原因。设计时应预留足够的伸缩缝变形量和支座允许变形量,保证曲梁沿切向的自由伸缩,同时采取一定的限位措施；对于支座脱空现象,可采取增大梁端支座间距,增强端部梁体抗扭性能的方法来处理。
[Abstract]:With the rapid development of urban rail transit in China, prestressed concrete curved girder bridge has been applied more and more. Curved girder bridge is a complicated spatial structure, and "bending and torsional coupling" is the most obvious force characteristic. Based on the basic theory of curved bridge and finite element method, based on the Fengsha railway bridge of Beijing metro line 14, the stress characteristics of prestressed concrete curved beam are analyzed in detail, and the influence of curve radius on the mechanical behavior of curved beam is summarized. In view of the common diseases of curved girder bridge in construction and operation, the effects of prestress load and temperature load on curved beam are studied, and the causes of web plate steel bundle side collapse, main beam "climbing and moving" and support detachment are analyzed. Some preventive measures are put forward. The results show that under the action of vertical load outside the plane, even the symmetrical load, the torsional moment in the curved beam will be larger and the corresponding torsional deformation will occur. This kind of torsion causes the internal and external forces of curved beam to be uneven, which mainly shows the stress difference in the inside and outside of the beam and the difference in the reaction force between the inner and outer supports of the double bearing with torsion. With the decrease of radius, the torsional moment of curved beam increases, and the force on both sides of the beam becomes more uneven, and the torsional deformation becomes more severe. Therefore, in the design of curved girder bridge, under the premise of satisfying other requirements, the larger curve radius should be chosen as far as possible. When the curve radius is very small or the tensile force is very large, the radial horizontal distribution force of prestressing force will easily cause the lateral collapse of web steel bundle during construction. For this reason, the prestressed steel bundle can be removed from the outside, the anti-avalanche steel bar is added, and the transverse partition plate is reasonably set up. In order to prevent the occurrence of this kind of disease, the methods of web anti-avalanche checking and so on are carried out. Torsion and temperature load caused by prestress are also the important reasons for "climbing and moving" of curved beam and void of support. Enough deformation of expansion joints and allowable deformation of supports should be reserved in design to ensure the free expansion of curved beams along the tangential direction, and certain limiting measures should be taken at the same time; for the phenomenon of support clearance, it is possible to increase the distance between the supports at the end of the beam, The method of strengthening the torsion resistance of the end beam body is used.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U445.7;U441

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