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Application of FE approach to deformation analysis of RC elements under direct tension
Jakubovskis, Ronaldas,Kupliauskas, Rimantas,Rimkus, Arvydas,Gribniak, Viktor Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.68 No.3
Heterogeneous structure and, particularly, low resistance to tension stresses leads to different mechanical properties of the concrete in different loading situations. To solve this problem, the tension zone of concrete elements is reinforced. Development of the cracks, however, becomes even more complicated in the presence of bar reinforcement. Direct tension test is the common layout for analyzing mechanical properties of reinforced concrete. This study investigates scatter of the test results related with arrangement of bar reinforcement. It employs results of six elements with square $60{\times}60mm$ cross-section reinforced with one or four 5 mm bars. Differently to the common research practice (limited to the average deformation response), this study presents recordings of numerous strain gauges, which allows to monitor/assess evolution of the deformations during the test. A simple procedure for variation assessment of elasticity modulus of the concrete is proposed. The variation analysis reveals different deformation behavior of the concrete in the prisms with different distribution of the reinforcement bars. Application of finite element approach to carefully collected experimental data has revealed the effects, which were neglected during the test results interpretation stage.
Application of FE approach to deformation analysis of RC elements under direct tension
Ronaldas Jakubovskis,Rimantas Kupliauskas,Arvydas Rimkus,Viktor Gribniak 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.68 No.3
Heterogeneous structure and, particularly, low resistance to tension stresses leads to different mechanical properties of the concrete in different loading situations. To solve this problem, the tension zone of concrete elements is reinforced. Development of the cracks, however, becomes even more complicated in the presence of bar reinforcement. Direct tension test is the common layout for analyzing mechanical properties of reinforced concrete. This study investigates scatter of the test results related with arrangement of bar reinforcement. It employs results of six elements with square 60×60 mm cross-section reinforced with one or four 5 mm bars. Differently to the common research practice (limited to the average deformation response), this study presents recordings of numerous strain gauges, which allows to monitor/assess evolution of the deformations during the test. A simple procedure for variation assessment of elasticity modulus of the concrete is proposed. The variation analysis reveals different deformation behavior of the concrete in the prisms with different distribution of the reinforcement bars. Application of finite element approach to carefully collected experimental data has revealed the effects, which were neglected during the test results interpretation stage.
Viktor Gribniak,Aleksandr K. Arnautov,Arvydas Rimkus 한국CDE학회 2021 Journal of computational design and engineering Vol.8 No.2
The elegant stress-ribbon systems are efficient in pedestrian bridges and long-span roofs. Numerous studies defined corrosion of the steel ribbons as the main drawback of these structures. Unidirectional carbon fiber-reinforced polymer (CFRP) is a promising alternative to steel because of lightweight, high strength, and excellent corrosion and fatigue resistance. However, the application of CFRP materials faced severe problems due to the construction of the anchorage joints, which must resist tremendous axial forces acting in the stress-ribbons. Conventional techniques, suitable for the typical design of the strips made from anisotropic material such as steel, are not useful for СFRP strips. The anisotropy of СFRP makes it vulnerable to loading in a direction perpendicular to the fibers, shear failure of the matrix, and local stress concentrations. This manuscript proposes a new design methodology of the gripping system suitable for the anchorage of flat strips made from fiber-reinforced polymers. The natural shape of a logarithmic spiral Nautilus shell describes the geometry of the contact surface. The continuous smoothly increasing bond stresses due to friction between the anchorage block and the CFRP strip surface enable the gripping system to avoid stress concentrations. The 3D-printed polymeric prototype mechanical tests proved the proposed frictional anchorage system efficiency and validated the developed analytical model.