预制空心板梁桥铰缝加固试验研究

Experimental Study on Reinforcement of Shear Connections in Precast Box-beam Bridges

空心板梁桥在公路桥梁中应用广泛,但随着使用年限增加,板梁铰缝及其附近铺装层发生破坏,严重时导致单板受力。采用加厚重做混凝土铺装层的方法对破损铰缝进行加固,制作了3组板梁加固节点的足尺模型,开展了不同受力模式下的静力加载试验,得到了加固后铰缝部位的破坏模式和极限承载力。结果表明:铰缝与板梁交界面率先发生开裂之后,试件的最终破坏均表现为混凝土铺装加固层的弯曲或剪切破坏,且不同破坏模式下的铰缝节点均表现出较好的延性。与基于全桥实体有限元分析得到的铰缝截面最不利内力设计值相比,加固后铰缝节点的抗弯和抗剪承载力分别高出3倍和1倍,该加固方法可在工程实践中推广应用。

Precast concrete box-beams have been widely used in highway bridges.However,as such bridges got aged,the wearing surfaces near the shear connections have been found to be cracking damaged,which will unavoidably lead to the so-called“single-beam bearing”.In this paper,the strengthening of shear connections by replacing damaged wearing surfaces with thick reinforced concrete pavementwas experimentally studied.Three full-scale specimens each containing three box-beam segments and two shear connections were fabricated,and the static tests considering different load cases were conducted.The failure modes and the ultimate bearing capacities of the specimens were obtained.Results show thatall specimens cracked originally at the bottom of shear connections and finally collapsed due to bending failure or shearing failure of upper pavements.Better ductility of specimens was also observed.By comparing with the maximum internal forces as derived from finite element analysis of whole bridge,the flexural and shear bearing capacities of strengthened shear connections are respectively 3 and 1 times higher,which indicates that the investigated strengthening method could be used in real applications.