带植筋新老混凝土粘结面剪切试验及有限元模拟分析

Shear test and finite element simulation analysis of bonding interface of new and old concrete with planting bars

新老混凝土良好结合是混凝土修补成功的关键,提出在粘结面上植筋来增强新老混凝土的粘结性能,通过采用剪切试验和有限元模拟方法综合分析有无植筋的新老混凝土试件的抗剪强度特征及植筋率和不同植筋排布方式对抗剪性能的影响。结果表明:无植筋试件的抗剪强度仅为整浇试件的30%左右,而植筋新老混凝土试件的抗剪强度将达到整浇试件的40%~70%;设置界面构造锚筋能够抑制裂缝的发展,使粘结面破坏具有一定的延性,增强新老混凝土粘结性能;在一定范围内增大植筋率可以提高混凝土构件的抗剪强度;采用三角形植筋排布方式的试件,其开裂荷载和破坏荷载均高于方形排布试件,钢筋平均应变也相对提高5%~10%。

The good combination of new and old concrete is the key to the success of concrete repair.It was proposed to plant bars on the bonding interface to strengthen the bonding performance of new and old concrete.Through the shear test and finite element simulation method,the shear strength characteristics of the new and old concrete specimens with or without planting bars and the effect of different planting arrangement on the shear performance were analyzed.The results show that the shear strength of the specimens without planting bars is only about 30% of the cast-in-place specimens,and the shear strength of the new and old concrete specimens with planting bars reaches 40%~70% of the cast-in-place specimens;the construction of interface anchorage bars can inhibit the development of cracks,and make the bonding interface damage have certain ductility,and enhance the bonding performance of the new and old concrete;increasing the planting bar rate within a certain range can improve the shear strength of concrete members;the specimens with triangular planting bar arrangement have higher cracking load and failure load than square-shaped planting bar arrangement specimens,and the average strain of steel bars is also increased by 5%~10%.