盖挖逆作地铁车站明暗双牛腿结构抗剪性能研究

为解决内蒙古自治区呼和浩特市盖挖逆作地铁车站钢管混凝土柱与后浇钢筋混凝土梁明暗双牛腿节点的设计难题，针对盖挖逆作地铁车站，提出一种新型的明暗双牛腿式钢管混凝土梁节点形式。通过ABAQUS模拟分析和模型试验验证，对不同设计参数条件下结构的抗剪性能进行研究。分析结果表明： 1)环形牛腿肋板与钢管壁之间的有效焊缝长度为影响牛腿结构抗剪承载力的主要参数，通过调节有效焊缝长度，可以明显改善牛腿结构的力学性能； 2）为确保剪力的有效传递，上环板穿心量宜取值为钢管柱直径的8%； 3）在实际工程中，梁柱节点处剪力较大时，可采用明暗双牛腿，其具有较高的承载力，力学性能好，具有较广泛的工程应用前景。

Investigation into Shearing Capacity of Visible Concealed Twin corbel Used in a Metro Station Excavated by Cut and Cover Top Down Method

The design of joints of concrete filled steel tubular (CFST) column reinforced concrete (RC) beam with visible concealed twin corbel in the metro station excavated by cut and cover top down method in Hohhot, Inner Mongolia is of great significance. As a result, a new type of CFST joint with visible concealed twin corbel is put forward, which is analyzed by simulation software ABAQUS and model test. Meanwhile, analysis is made on the key design parameters of the joint. The results show that: (1) The effective weld length between the annular corbel rib plate and the steel pipe wall is the main parameter affecting the shear resistance of the node, and by adjusting which the mechanical properties of the joint can be significantly improved. (2) In order to ensure the effective transfer of shear force, 8% of the diameter of steel tube column should be taken as the appropriate value. (3) When the shear force at the beam column joint is large, the visible concealed twin corbel can be used, which has high bearing capacity and excellent mechanical properties as well as a wide range of engineering application prospects.