连续刚构桥跨中节段混凝土接缝抗弯性能研究

为解决大跨径连续刚构桥在后期运营中常发生的刚度下降和跨中挠度持续增加的问题，采用节段混凝土接缝抗弯试验模拟连续刚构桥的悬臂施工，考虑试件是否分段以及分段后截面是否凿毛、钢筋布置状况、预应力等因素对大跨度连续刚构桥跨中挠度的影响规律进行研究，并对比分析不同弯曲下挠理论，为桥梁跨中节段接缝抗弯下挠控制提供参考依据。试验结果表明：凿毛使接缝处混凝土结合能力得到有效提升；随着布筋间距的增大，节段混凝土抗弯性能的提升逐渐减弱；提高预应力施加大小能有效延缓梁体开裂时机并且施加高水平的预应力更能有效地控制跨中下挠；在偏安全的情况下，以绝对静矩代替惯性矩的挠度计算值更接近实测值。

Study on flexural behavior of concrete joints in mid - span of continuous rigid frame bridge

In the later operation of long-span continuous rigid frame bridge, the problems of stiffness decrease and mid-span deflection increase often occur. To solve this problem, it is necessary to study the influence law of mid-span bending deflection of long-span continuous rigid frame bridge. In the study, the cantilever construction of continuous rigid frame bridge is simulated by segmental concrete joint flexural test. And the study considered that whether the specimen is segmented, whether the section is chiseled after segmentation, reinforcement layout, prestress and other factors. Meanwhile, different bending deflection theories are compared and analyzed, which provides reference for the bending deflection control of bridge segmented joints. The experiment shows several results. Removal of cross section slurry can effectively improve the binding capacity of concrete at joints. With the increase of the spacing between bars, the improvement of the flexural performance of concrete segments is gradually weakened. Increasing perstress can effectively delay the cracking time of the beam. At the same time, applying high level prestress is available to control the mid-span deflection. In the case of safety, the calculated value of deflection using absolute static moment instead of inertia moment is closer to the measured value.