Deterioration Process and Evaluation of Strengthening Methods for Reinforced Concrete Bridge Deck

交通越繁忙，报告的桥面铺装板损坏案例就越多。弄清冲切破坏的机理是非常重要的。另外，国内外对破损桥面铺装板的加固方法也有很多，可以分为两种。一种是所谓的表面加固方法。钢纤维混凝土铺装和D-RAP方法属于这一类。另一种是所谓的底面加固法。在这种情况下，钢板或碳纤维板(CFRP)用环氧树脂粘接在楼板的下表面。为了阐明冲剪破坏的机理并对上述加固方法进行评价，本文进行了试验研究，得到的主要结论如下：1)加载试验中，板在加载位置附近径向的表面压应变先是增大，在冲剪破坏发生之前逐渐减小，后期甚至变为拉伸，而环向应变单调增大。结果表明，在加载过程中，受力部位附近的板内部结构发生了应力流的变化。2)冲切剪切裂纹的突然扩展与最终阶段存在的弯曲裂纹无关。3)表面加固的效果与相同深度的板相当。4)在底面加固的情况下，弯曲刚度有较大幅度的提高。这种增加是由于胶合材料的止裂作用引起的。

The heavier the traffic becomes, the more cases of damaged bridge deck slabs are reported year by year. It is basically important to clarify the mechanism of punching shear failure. In addition, various strengthening methods for damaged bridge deck slabs have been proposed and they can be divided into two. One is so-called surface strengthening method. SFRC surfacing and D-RAP method are included in this category. The other is so-called bottom surface strengthening method. In this case, steel plates or carbon-fiber sheets (CFRP) are glued on the lower face of slab by epoxy resin. Experimental studies were made to clarify the mechanism of punching shear failure and to evaluate the strengthening methods stated the above.Principal conclusions derived are as follows ;1) During loading tests, surface compression strain of slabs in radial direction near loading position increased at first and it turned to decrease fairly before punching shear failure occurred and even became tension at final stage, though strain in circumferential direction increased monotonously. The fact suggests that the changing of stress flow occurred in the internal structure of slab near loading position during loading.2) Punching shear cracking spread abruptly irrespective to the existing bending cracks at final stage.3) The effectiveness of surface strengthening method showed just as the same level as the slabs with same depth.4) In case of bottom surface strengthening flexural rigidity increased largely. The increase is caused by the arresting effect of crack re-opening with the glued materials.