铝合金板加固钢筋混凝土梁的剥离破坏机理试验研究

剥离破坏是铝合金板加固钢筋混凝土（RC）梁常见的早期破坏形式，为了避免剥离破坏的出现，对铝合金板加固RC梁的剥离破坏机理开展试验研究。制作了24根RC梁，利用结构胶将铝合金板粘贴在RC梁底部。为了研究附加锚固对剥离破坏的影响，部分试验梁在铝合金板特定位置设置了化学螺栓或U形箍。通过铝合金板加固RC梁的简支梁三分点对称单调加载试验，得到铝合金板加固RC梁的4种破坏模式：适筋破坏、超筋破坏、板端剥离破坏和中部裂缝剥离破坏。剥离破坏的原因是界面剪应力过大。利用铝合金板应变片的试验数据，得到了铝合金板的粘贴界面剪应力分布曲线，分析了界面剪应力分布规律：在板端取得最大值后迅速下降至零值，RC梁裂缝处界面剪应力发生突变。板端剥离破坏发生的机理：铝合金板端界面剪应力达到铝合金板与混凝土的粘贴强度后，界面剪应力导致保护层内混凝土剥离；中部裂缝剥离破坏发生的机理：界面剪应力在混凝土齿状块体端部产生的正应力大于混凝土受拉强度，导致混凝土齿状块体从梁体剥离。在此基础上，得到了两种剥离破坏的判别式，并结合试验数据验证了判别式的准确性。

Experimental analysis of debonding failure mechanism of reinforced concrete beam strengthened with aluminum alloy plate

Debonding failure is a common early damage form of aluminum alloy plate strengthened RC beam. In order to avoid the occurrence of debonding failure, the experimental research on the mechanism of aluminum alloy plate strengthened RC beam debonding failure was conducted. 24 RC beams were fabricated, and the aluminum alloy plates were adhered to the bottom of the RC beams with structural adhesive. In order to study the effect of additional anchoring on debonding failure, part of the test beams is equipped with chemical bolts or U-shaped hoops at specific positions on the aluminum alloy plate. Through the three-point symmetrical monotonic loading test of simply supported beams with aluminum alloy plates strengthened RC beams, four failure modes of RC beams strengthened by aluminum alloy plates are obtained:suitable reinforcement failure, over-reinforced failure, debonding failure at end plate or at mid-span induced by crack. The debonding failure is mainly caused by the excessive interfacial shear stress. Therefore, the test data of the strain gauge of the aluminum alloy plate were used to obtain the interfacial stress distribution curves, and the principle of interface shear stress distribution is analyzed. After reaching the maximum value at plate end, the stress quickly falls to around null. The interfacial shear stress in the cracking section of RC beam has a sudden change. The mechanism of debonding failure was analyzed:the mechanism of debonding failure at plate end is that after the interfacial shear stress reaches the bonding strength of the aluminum alloy plate and concrete, the interfacial shear stress will peel off the concrete in the protective layer; The mechanism of mid-span crack induced debonding failure is that the interfacial shear stress peels off the concrete fragment blocks from the beam body after the normal stress generated at the end of the concrete block is greater than the concrete tensile strength. On this basis, the discriminant formulae of two kinds of debonding failure were obtained, and the accuracy of the discriminants was verified by combining the test data. Above work provides a theoretical basis for the engineering application of RC beams strengthened with aluminum alloy plates.