超大跨径UHPC连续箱梁桥接缝设计及模型试验

发布时间：2018-02-16 22:09

  本文关键词： 超大跨径 超高性能混凝土 悬臂拼装 接缝优化设计　出处：《湖南大学》2014年硕士论文　论文类型：学位论文

【摘要】：超大跨径UHPC连续箱梁桥是利用UHPC材料优良的抗拉、抗压性能，采用薄壁结构、密集横隔板箱梁和部分体外预应力相结合的一种新型连续梁结构。与传统连续梁桥相比，具有跨越能力大，自重轻，稳定性强，后期运营跨中徐变挠度小，易于维护检修等优点。针对超大跨径UHPC连续箱梁桥，本文提出了悬臂拼装法施工的牛腿式UHPC节段间接缝，并对其进行参数优化分析，研究简化的单牛腿接缝的抗剪性能，考察横隔板对接缝抗剪性能的影响，考察箱梁腹板竖向接缝是否满足结构受力要求。鉴于此，本文作者主要进行了以下研究工作： （1）建立接缝抗剪有限元模型，通过数值分析，比较常规混凝土接缝与UHPC接缝的抗剪性能，考察单牛腿接缝与剪力齿块接缝受力性能，并对UHPC单牛腿接缝的倾角、深高比、齿梁高之比进行优化设计。计算结果表明：UHPC接缝抗剪性能远超于常规混凝土接缝，UHPC单牛腿接缝设计合理可行，其最优水平倾角为0°~45°，深高比≥1/10，齿梁高比为1/3~2/3。 （2）利用优化结果设计制作UHPC双悬臂梁接缝模型，对比研究不同横隔板数目的悬臂梁段在材料弹性下接缝的抗剪性能，并考察两种结构剪切破坏的全过程。通过二者试验结果的对比考察隔板对结构接缝的抗裂和承载力方面的作用。静力试验的结果表明：薄壁箱梁腹板接缝抗剪性能强，密集横隔板能提高接缝抗剪承载力，接缝角趾开裂应变达到455με，远大于普通混凝土的接缝强度，抗裂安全度可达1.63。 （3）建立试验梁的有限元模型，对试验梁进行数值分析，更加细致的考察结构各方面的性能，深入分析横隔板对接缝受力性能的影响，并与试验结果相比较。结合试验结果及有限元分析得到：UHPC单牛腿接缝的抗剪性能足够强，密集横隔板能够明显提高接缝的抗剪性能。 （4）简单介绍主跨400m的UHPC连续箱梁桥，并建立全桥MIDAS有限元模型，分析其整体受力情况及收缩徐变性能。分析结果显示超大跨径UHPC连续箱梁桥的应力分布均匀，能够满足结构的受力要求，运营阶段跨中下挠的挠度小，可以有效避免成桥后桥梁下挠开裂的风险。 （5）根据整体计算模型建立箱梁支座附近梁段的局部有限元模型，分析箱梁在正常使用极限荷载工况下支座附近节段的受力性能，确定该方案的腹板抗剪及接缝抗剪性能力能否满足结构受力的要求。分析结果显示该结构牛腿接缝保持良好的连接功能，结构的整体性,接缝处及腹板的主拉应力水平较低，不会发生开裂，，能够适应UHPC单向预应力体系超大跨径梁桥的受力要求。
[Abstract]:Large span UHPC continuous box girder bridge is a new type of continuous beam structure which combines thin wall structure, dense transverse diaphragm box girder and partial external prestressing force by using the excellent tensile and compressive properties of UHPC material. Compared with the traditional continuous girder bridge, the large span UHPC continuous box girder bridge is a new type of continuous beam structure. It has the advantages of large span capacity, light weight, strong stability, small creep deflection in late operation span, easy maintenance and repair, etc. Aiming at large span UHPC continuous box girder bridge, this paper puts forward a new method of cantilever assembling method, which is used to construct the joint between the segments of the UHPC segment, which is constructed by cantilever assembly method, and is easy to be maintained and overhauled. The parameter optimization analysis is carried out to study the shear resistance of the simplified single corbel joint, to investigate the influence of the shear resistance of the transverse diaphragm butt joint, and to investigate whether the vertical joint of the web of the box girder meets the structural stress requirements. The author has carried out the following research work:. 1) the finite element model of joint shear resistance is established. Through numerical analysis, the shear behavior of conventional concrete joint and UHPC joint is compared, the mechanical behavior of single leg joint and shear tooth block joint is investigated, and the angle of inclination and the ratio of depth to height of single leg joint of UHPC are investigated. The calculation results show that the shear resistance of the 1: UHPC joint is much better than that of the conventional concrete joint. The optimum horizontal inclination angle is 0 掳45 掳, the depth to height ratio is 鈮

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