185m高墩大跨刚构桥悬臂施工下的超高墩效应分析

发布时间：2018-04-02 17:01

本文选题：超高墩效应　切入点：非线性　出处：《长安大学》2015年硕士论文

【摘要】：185m超高墩大跨T构悬臂施工中,墩身的柔性尤为突出,在温度和其他不平衡等因素作用下,墩身极易出现纵向挠曲变形,致使T构发生“跷跷板”变形,随之加剧结构稳定性降低,如此循环带来超高墩效应不断放大。因此,必须结合实际深究悬臂施工中的超高墩效应,为此类超高墩结构积累更多理论与实践经验。本文结合三水河特大桥墩高185m的14#超高墩大跨T构悬臂施工,首先,根据非线性分析理论,分别采用弹性、考虑几何非线性和考虑材料非线性分析方法,对超高墩T构最大悬臂状态进行静力和稳定性分析,并且研究不同墩高和三种墩身形式下超高墩稳定性差异。其次,根据长期现场气温观测和24小时墩身截面温度观测,总结出温度变化规律;分别对升温、降温和日照温差在不同施工状态下进行超高墩效应分析,以及在一个节段内日照温差交替变化下的响应。最后,结合现场实际悬臂施工监控中的标高误差源,归结出超高墩大跨T构悬臂施工中引起不平衡作用的因素,分析荷载偏差、张拉预应力、不同步施工、方案变更和挂篮跌落情况带来的超高墩效应,同时给出一定的实际建议和相应预防措施。经过分析,对于超高墩结构必须考虑其几何和材料非线性,尤其几何非线性对超高墩偏位影响比重在15%左右;建议墩高超过120m的墩界定为超高墩,具有明显高墩效应;墩身形式的选择没有规定的最优选择,根据不同桥梁结构考虑重点侧重选取;日照温差变化下,外界温度最大时,薄壁内侧温度并不是最低的,最低温度基本出现在中间壁厚位置处,呈现非线性关系;在施工悬臂梁端标高误差分析中,温度作用下的超高墩T构位移响应在2cm左右,其余误差多由不平衡作用产生;相同节段块连续不同施工工序出现正负温度作用和正负不平衡作用,其结果不会完全抵消,只会削减一部分;施工挂篮跌落过程存在动力时程效应,超高墩和悬臂梁强度均可满足,变形量过大,所以必须避免出现此情况。总之,积累更多实际超高墩施工经验才能丰富超高墩效应的理论分析。
[Abstract]:The flexibility of the pier body is especially prominent in the construction of the long-span T-frame cantilever of 185m super-high pier. Under the action of temperature and other unbalance factors, the pier body is prone to appear longitudinal flexural deformation, resulting in the "seesaw" deformation of T structure.As a result, the stability of the structure decreases, and the effect of super-high pier is magnified by this cycle.Therefore, it is necessary to study the effect of super-high pier in cantilever construction, and accumulate more theoretical and practical experience for this kind of super-high pier structure.In this paper, combined with the construction of T-structure cantilever of 14# super-high pier with 185m height of Sanshuihe Bridge pier, firstly, according to the theory of nonlinear analysis, the elastic, geometric and material nonlinear analysis methods are adopted, respectively.The static and stability analysis of the maximum cantilever state of the T structure of the super-high pier is carried out, and the difference of the stability of the super-high pier under different pier heights and three types of pier body is studied.Secondly, according to the long-term field temperature observation and the temperature observation of the section of the pier for 24 hours, the variation law of temperature is summarized, and the effects of super-high piers are analyzed under different construction conditions, such as temperature rise, temperature drop and sunshine temperature difference.And the response under the alternating variation of the temperature difference of sunlight in a segment.Finally, combined with the elevation error source in the field actual cantilever construction monitoring, the factors that cause imbalance in the construction of the long-span T-frame cantilever with super-high piers are summed up, and the load deviation, tensioning prestress, and asynchronous construction are analyzed.The effect of super high pier caused by scheme change and drop of hanging basket is also given, and some practical suggestions and corresponding preventive measures are given at the same time.After analysis, the geometric and material nonlinearity must be considered for the structure of super-high pier, especially the influence of geometric nonlinearity on the deviation of super-high pier is about 15%, it is suggested that the pier with height over 120 m should be defined as super high pier, which has obvious high pier effect.There is no prescribed optimal choice for the form of piers. According to different bridge structures, the emphasis is on the selection. Under the variation of sunshine temperature, when the outside temperature is the largest, the inner temperature of the thin wall is not the lowest.In the analysis of elevation error at the end of cantilever beam, the displacement response of T structure of super-high pier under the action of temperature is about 2cm, and the other errors are mostly caused by unbalanced action.The effect of positive and negative temperature and positive or negative imbalance in different construction processes of the same segment block will not be completely offset, only a part will be reduced, and there will be dynamic time-history effect in the falling process of construction basket.The strength of superhigh pier and cantilever beam can be satisfied and the deformation is too large, so this situation must be avoided.In a word, the theoretical analysis of superhigh pier effect can be enriched only by accumulating more practical construction experience.
【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】：U448.23;U445.466

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