【作者】 曹鹏；

【导师】 张谢东；

【作者基本信息】 武汉理工大学 ， 道路与铁道工程， 2009， 硕士

【摘要】 一直以来弯梁桥缺乏专门的指导规范,对于小半径的弯桥仍按一般直梁桥来设计是不合适的,而且目前的桥梁规范没有考虑弯桥上作用多辆超载汽车和桥面堵车导致满布汽车这些越来越常见的现象,另外,小半径的弯桥弯扭耦合效应更加突出,这就要求加深对以上问题的理解。本文首先总结了半径较小的弯桥受力表现出明显不同于直桥的特点:弯曲和扭转耦合,内外梁体受力不均匀、抗扭稳定性受到活载、温度效应影响很大。在设计中应该充分认识到这些因素对抗扭稳定的影响。接着,阐述了用能量法分析连续弯梁桥的理论基础,对两种典型的支承方式下的连续弯梁桥,列出了详细的内力、反力计算公式;指出了预应力设计的原则和基本步骤。强调预应力的设计对调整全桥内力的分布和改善结构的抗扭效果有重要的影响。其后,本文运用Midas FEA、Civil分析最不利荷载组合下的小半径弯梁桥的内力、变形,分别建立了小半径预应力混凝土弯桥、钢筋混凝土弯桥的梁单元、实体单元模型,通过对比不同支承方式下弯桥在荷载组合下的支座反力和扭矩,详细论证弯桥梁体重心、预应力、活载及温度作用影响结构的抗扭效果;讨论了支承方式对结构抗扭稳定性的影响,认为双支座抗扭是小半径匝道桥设计中应优先考虑的支座布置方式;通过分析支座反力影响线与车辆行驶位置的关系,初步查明了近年来匝道桥倾覆事故的原因;并建议通过试算对独柱点铰支承的弯桥设置合理的预偏心值,来达到较好的抗扭效果;通过模型计算和分析,总结出:应从预应力的合理设计、支座布置方式的合理选取这两方面来以确保弯桥在运营期间避免由于温度效应、汽车离心力、预应力引起梁体向弯外侧爬移、倾覆,出现支座脱空、墩顶横向偏压破坏等病害。对独柱点铰支承的小半径弯桥,说明了设置预偏心以调整梁体的扭矩、改善支座反力分布的原理,并通过对实例的试算,得出合理的支座预偏心值。最后,讨论了温度效应对于小半径弯桥的影响,通过对不同支承形式下的温度荷载引起的反力和扭矩的对比,强调了应设置合理的支座来避免温度效应对弯桥的不利影响,防止弯箱梁出现的“爬移”和支座脱空等常见病害。更多还原

【Abstract】 Special guiding criterion is absent in the design of curve bridge . It is insufficient to design in common girder bridge method, and the current bridge criterion doesn’t consider the common phenomena of many over loading vehicles on the bent bridge and too many vehicles on the bridge caused by traffic jam. What is more, the coupling effect of bend-twist was more significant when we selected smaller radius curve . Designers are required to deepen their understanding of the above problems.At first , static behavior which is obviously different from common girder bridge was summarized,such as the coupling effect of bend-twist, the foce difference between the inside and the outside, especially the vehicle. The influence of these factors on the anti-torsion stability should be estimated correctly in the design.Subsequently, the theoretical basis of analysis of continuous curved girder bridge by energy method is introduced , and calculation formulas of the internal force and reaction in continuous curved girder bridge with two typical bearing forms are listed out in detail. Principles and basic steps of prestress design are also illustrated .Importance of the design of prestress which has made great contribution to the adjustment of internal force distribution and the improvement of structural torsional effect was emphasized.In this paper the internal force, and distortion of bent girder bridge which has bigger curvature under the most disadvantageous load combinations are analyzed by using Midas FEA and Civil, the beam and solid element model of prestressed reinforced concrete curve bridge and reinforced concrete curve bridge are respectively established, centering on the bearing reaction and torque , various bearing condition are compared under load combination ; The fact that the center of gravity, prestress, temperature and live load effect affect the anti-torsion effect of the structure are demonstrated in details; The effect of bearing form on the stability of anti-torsion are discussed; the double anti-torsion bearing should be primarily considered in the ramp bridge design, by analysing the relation between influence line of bearing reaction and loading location ,the preliminary reasons of bridge overturning accident in recent years are find out;some suggestions on curved bridge supported by single-column with hinge bearing that reasonable bearing pre-eccentricity should be set up by tentative calculation are proposed to in the text. At the end it comes to the conclusion:Arranging proper lay-out of reinforcement and selecting reasonable supporting mode are the main measures for preventing the girder from moving outside and overturn caused by temperature effect, vehicle centrifugal force and prestress during operation, and avoiding damages such as gapped support, horizontal deflection of capping.As for smaller radius curved bridge with point-hinge bearing, the principle of setting pre-eccentric to adjust the longitudinal torque and reaction distribution of the bridge is described, and reasonable pre-eccentric value is achieved by means of trial calculation.Finally, the effects of temperature on smaller radius curved bridge is illustrated. centering on the bearing reaction and torque , various bearing condition are compared under temperature load, the importance of selecting reasonable bearing to avoid detrimental effect caused by temperature is emphasized, which prevent the girder from moving outside, as well as avoids damages such as gapped support.更多还原