Research On The Shear Performance Of Section At The End Of Superposed Concrete Beam

In China superposed concrete beams were widely used in precast concrete structure. The sections between superposed beam and cast-in-place concrete node were usually critical positions of the structure. According to industry standard of our country, "Technical specification for precast concrete structuresJGJ1-2014", the shear capacity of the section should be checked by the calculation formulas in this specification. However the shear capacity of this section at the end of superposed beam was not studied in depth. The calculation formulas in the specification were mainly based on the results of studies in Japan, America and China.This paper mainly focused on the shear capacity of the section between superposed beam and cast-in-situ concrete node, which had two components:the interface between PC and cast-in-place concrete, section of the post-cast concrete layer.4 groups of full-scale specimens simulating the sections subjected to pure shear and 2 groups of full-scale specimens simulating the sections subjected to both shear and bending were designed and tested. FEM analysis was carried out on the specimens by Abaqus. By comparing, the results of the test matched well with FEM analysis results. Basing on the research results, following conclusions could be drawn:1.Pure shear failure occurred at the keys and post-cast concrete layers during the test.2.The shear capacity of the section was influenced by the reinforcement ratio and the thickness of post-cast concrete layer. The higher of the reinforcement ratio and the thicker of the post-cast layer brought the higher of the shear capacity.3.The failure mode of the section subjected to both shear V and bending M was influenced by M/V ratio. When reinforcement ratio was 1%, bending failure occurred with M/V?1 and diagonal shear failure occurred with M/V<1.4.The mechanization of pure shear failure mode was analyzed and shear force to slip curve of the section was proposed.5.The calculation formulas of the shear capacity of the section were proposed, as also some structural details requirements. Some expectations of the following research were suggested.