Papers by Keyword: Beam

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Authors: Jia Chao Zhang, Lei Ming Zhang, Xi La Liu
Abstract: Reinforced concrete (RC) frame with masonry infill walls is a very common structural system in low and medium rise buildings. The infill walls are usually considered as non-structural components in the design or assessment of buildings. However, many damages in earthquakes have shown that the infill walls can significantly change the structural response to seismic action. Consequently the evaluation of the seismic performance of RC frame with masonry infill walls becomes very important, and also turns to be a major challenge for structure engineers. In this paper a beam-and-column (BAC) macro model for walls is proposed to simulate the masonry infill walls in RC frames. In this model, the masonry panel is replaced by an equivalent rigid frame which is made up of some beam-and-column members. The geometric parameters of each member can be determined simply by equivalent stiffness combined with the original dimensions of wall panel. The physical characteristics are described directly by material properties of wall panel under investigation. To validate the rationality of proposed model, a masonry-infilled RC frame under cyclic reversed loading is analyzed by the proposed model. The results, including crack pattern, load versus displacement relation are then compared with the experiment response. Good agreements are found.
Authors: Leandro Mouta Trautwein, Luiz Carlos de Almeida, Ricardo Gaspar
Abstract: This paper focuses on the assessment of the shear strength prediction established in the brazilian concrete code, NBR6118/2007[1], for reinforced concrete beams without web reinforcement. The values obtained by using the brazilian code equation are compared with a significant number of available experimental data and with those predicted by the expressions of other national and international codes, such as CEB-FIP MC90[2] and ACI-318/11[3]. The brazilian concrete code regarding shear capacity of reinforced concrete elements are explicitly assumed to be valid only for concrete strengths up to 50 MPa. It is shown that the code equation may be unconservative in a large number of cases. This discrepancy increases with increasing concrete strength, decreasing longitudinal reinforcement ratio and increasing beam depth.
Authors: Wei Tao Zhao, Tian Jun Yu, Yi Yang
Abstract: One of the most significant components of aircraft design is the wing, the wings are the main lifting surfaces that support the airplane in flight. The structures of wings must have enough strength and rigidity to ensure the safe of the aircraft. Usually, the displacements of the structures are calculated by using finite element method. But it is very difficult to select a reasonable finite element model to approximate the actual structure. In this study, two models are adopted to calculate the displacements of the wing structure. The first is a model of rod and shear plate, the second is a model of beam and shell. The disadvantages and advantages of two models are discussed. As seen from the comparison with the test date, two models proposed are both feasible to analyze the wing structure.
Authors: Yao Ting Zhang, Yi Zheng, Hong Jian Li
Abstract: A dynamic test of two unbonded fully prestressed concrete beams has been conducted. The results indicate that the natural frequency of beams increases with the prestress force, which is opposite to the analytical arguments for homogeneous and isotropic beams subject to axial force. This paper explains the change in frequencies by discussing the change in the elastic modulus. A modified formula is also proposed, and the experimental data agree well with the theoretical analysis.
Authors: E.K. Izrailov, V.F. Ezhov
Abstract: A new method and devices for cooling of atomic hydrogen up to the values less than 100 µK aimed for the development of the optical frequency standard with significantly improved parameters (Δν/ν£1 x 10-16) is discussed. The method exploits the unique properties of atomic hydrogen such as atomic hydrogen does not condense at temperatures as low as 20µK and can not be heated by IR radiation in the absence of atom-wall collisions. Therefore, the most efficient and well-known gas cooling technique can be employed, namely, the adiabatic expansion of the volume occupied by the gas. This approach is used in a cryogenic gas expansion machine. It is suggested to use the adiabatic expansion of the volume of the magnetic atomic trap containing atomic gaseous hydrogen for embodiment of this idea.
Authors: Song Xiang
Abstract: A n-order shear deformation theory is used to study the free vibration of functionally graded beams. Present theory satisfies the zero transverse shear stress boundary conditions on the top and the bottom surface of the beam. The natural frequencies computed by present theory are compared with previous published results which demonstrate the accuracy of present theory.
Authors: Hong Zhi Jia, Jia Bin Sun, Yu Fei Wu, Xin Sheng Xu
Abstract: Beam reinforcement is reduced to mechanics behavior of structures of multilayer materials in this paper. An analytical method is presented based on Hamiltonian system. In the system, displacements and stresses are pairs of dual variables. The state vectors of the system describe directly connective conditions on the interfaces of two materials and structures so that the rule of normal and shear stresses on the interface can be revealed. Based on the criterion of lamination crack, the interface strength is determined. Results show that the lamination crack correlates highly with the ratios of material constants and geometrical parameters of structures. The result and conclusion provide a design criterion for structure reinforcement.
Authors: Z.N. Yin
Abstract: A three Degree-of-Freedom (DoF) mass-spring model is proposed to predict the dynamic response of clamped supported beams subjected to blast loads at the mid-span of the beam. The stiffness of inelastic spring is defined from the relationship between force and mid-span displacement of beams subjected to blast loads. The lumped mass is calculated from the equivalency between the model and beam based on the fundamental frequency. Clamped supported solid beams and T-beams are taken as typical examples to verify the proposed model. And the influence of geometric parameters on deformation behavior is discussed in details.
Authors: Yan Mei Lv, Wei Jian Yi
Abstract: An energy absorbing stiff test facility has been developed for obtaining stable and controlled shear failure of reinforced concrete beams. Using two hydraulic jack and a cross steel beam to act as the stiffener and energy absorbing elements, test facility allows the monitoring of the complete curve of load versus mid-span deflection (including the post-peak region) of shear critical beams. To prove the feasibility of this test facility, the stiff test facility was measured when test facility were loaded up and down. Then, the shear failure experiments of 4 full size reinforced concrete beams were processed. The results indicate that the post-peak branch of the load versus mid-span deflection of the shear-critical reinforced concrete beams without web reinforcement was steeper than that of beams with web reinforcement and hence the stiff test facility was more stable for beams with web reinforcement.
Authors: Jian She Peng, Gang Xie, Liu Yang, Yu Quan Yuan
Abstract: This paper presents a new time-domain DQ (differential quadrature) method for structural vibration analysis. It adopts differential quadrature method both in space domain and in time domain on the basis of governing partial differential equation and initial-boundary value condition of vibration problems of structures, and gets new differential quadrature linear equations with complete initial-boundary value conditions for solving all parameters of the displacement-field. The examples in this paper show the time-domain differential quadrature method is a useful and efficient tool for structural vibration analysis.
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