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Research on Angle Connector in Composite Beam
Kewei Ding,Xinqi Zhang,Yunlin Liu,Shulin He,Jingfeng Wang,Wanyu Shen 한국콘크리트학회 2022 International Journal of Concrete Structures and M Vol.16 No.3
As a critical component for steel beam and concrete slab to work together, the strength of the shear connector affects the flexural load capacity and stiffness of the composite beam. Connectors were generally studied for longitudinal shear resistance. However, transverse shear needs to be considered when the main beam is far away and the transverse connection is weak. In this paper, an angle connector pre-embedded in the precast slab was proposed, and its pre-embedded position makes it exhibit better transverse shear resistance. To assess the strength, stiffness, and slip capacity of the angle connector, two groups of composite beam with precast slabs negative moment flexural were tested, then several finite element groups were simulated in push-out test. The test variable was the existence of angle connectors, and the variables simulated were the yield strength of the angle connector and its flange thickness. The results showed that the composite beam with angle connectors has greater stiffness than ordinary ones, with little difference in flexural strength capacity and less slippage. The results show that angle connectors can replace extending rebars in precast slabs, which will reduce construction costs. In addition, a new design equation was proposed, including the yield strength of the connector and the thickness of its flange which are not unified in the current equations. The simulations determined the strength of the angle connectors in relation to the yield strength of the angle connector and its web thickness.
Solidification of uranium mill tailings by MBS-MICP and environmental implications
Niu Qianjin,Li Chunguang,Liu Zhenzhong,Li Yongmei,Meng Shuo,He Xinqi,Liu Xinfeng,Wang Wenji,He Meijiao,Yang Xiaolei,Liu Qi,Liu Longcheng 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.10
Uranium mill tailing ponds (UMTPs) are risk source of debris flow and a critical source of environmental U and Rn pollution. The technology of microbial induced calcium carbonate precipitation (MICP) has been extensively studied on reinforcement of UMTs, while little attention has been paid to the effects of MICP on U & Rn release, especially when incorporation of metakaolin and bacillus subtilis (MBS). In this study, the reinforcement and U & Rn immobilization role of MBS -MICP solidification in different grouting cycle for uranium mill tailings (UMTs) was comprehensively investigated. The results showed that under the action of about 166.7 g/L metakaolin and ~50% bacillus subtilis, the solidification cycle of MICP was shortened by 50%, the solidified bodies became brittle, and the axial stress increased by up to 7.9%, and U immobilization rates and Rn exhalation rates decrease by 12.6% and 0.8%, respectively. Therefore, the incorporation of MBS can enhance the triaxial compressive strength and improve the immobilization capacity of U and Rn of the UMTs bodies solidified during MICP, due to the reduction of pore volume and surface area, the formation of more crystals general gypsum and gismondine, as well as the enhancing of coprecipitation and encapsulation capacity