凹槽销栓型竹-混凝土连接件的力学性能

为了研究凹槽销栓型竹-混凝土连接件的力学性能,对2组共6个凹槽销栓型连接件进行了推出试验,位移计测量法和数字图像相关法被用于测量界面滑移。结果表明,凹槽销栓型竹-混凝土连接件的破坏始于混凝土的剪切破坏,延性系数较低,破坏模式属于脆性破坏; 销栓下垂直钢筋可有效提高凹槽销栓型竹-混凝土连接件的承载力,但会引起连接件区域外混凝土剪切破坏,建议增强连接件区域外相关混凝土的抗剪承载力; 由于连接件破坏损伤主要发生于连接件凸起混凝土的根部,集中破坏一侧凹槽位置处的滑移值相对上、下显著偏小,建议凹槽销栓型竹-混凝土连接件的混凝土凸起部分增设构造钢筋,抑制滑移界面破坏向混凝土梁体内部的转移。
In order to study mechanical properties of notch-dowel connections of bamboo-concrete, two groups of six notch-dowel connections were investigated by the push-out test. The displacement measurement method and digital image correlation method were used to measure the interface slip. The accuracy and validity of tests can be verified by comparing results of the two methods, and the data obtained by the digital image correlation method are much more comprehensive than the displacement measurement method. The failure mode of notch-dowel connections of bamboo-concrete is different from the notch connections of bamboo-concrete and the dowel connections of bamboo-concrete. Experimental results show that the failure of notch-dowel connections of bamboo-concrete starts from the shear failure of concrete, and bamboo has no significant damage at the joint. The dowel is bent down from its end. The failure of notch-dowel connections of bamboo-concrete is controlled by concrete failure. Moreover, the ductility coefficient is low and the failure mode is brittle failure. The vertical steel reinforcements under dowels can effectively improve the strength of notch-dowel connections of bamboo-concrete. However, it will cause the shear failure of concrete outside the connected region. Once the concrete failure, the load will drop rapidly. It is suggested that the shear strength of the relevant concrete outside the connected region should be reinforced. Because the failure of connectors mainly occurs at the root of concrete bulges, the slip at the notches is obviously smaller than that at the top and bottom. It is suggested that the steel reinforcements should be added in concrete bulges for notch-dowel connections of bamboo-concrete, restraining the transferring failure of the slip interface to the inside of the concrete beam body. The interface slip values of the specimens at different heights are basically constant under the same load level. However, a smaller slip appears near the notch center. Before the peak load, the displacement field distribution of bamboo indicates that the bamboo material above the notch center subjected to the concrete compression is slightly larger than the displacement of the bamboo below the center of the notch. After the peak load, the joint is