Papers by Keyword: Reinforcement

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Authors: Dan Huang, Yan Li Wang, Ying Wang, Hong Bao Cui, Xue Feng Guo
Abstract: The thermodynamic analysis in Mg-SiO2 system was conducted for the determination of the priority reaction at experimental temperature. Then, Mg2Si reinforced Mg alloy was synthesized through reaction in Mg-SiO2 system at 730°C, whose Si mass fraction is up to approximately 10%. The thermodynamic analysis and microstructure investigation results show, that generation of reinforcing phase of Mg2Si in Mg alloy from the reaction in Mg-SiO2 system is feasible with lower free energy than that in Mg-Si at the same temperature; and under the experimental temperature and solidification condition, the microstructure of Mg-10Si alloy is composed of coarse primary Mg2Si dendrite crystal, Chinese script type eutectic Mg2Si, and α–Mg phase, the formation of α–Mg holes is resulted from the relatively high cooling rate leading to a deviation from the equilibrium diagram during solidification.
1775
Authors: Chang Liang Zhang, Shang Jin Huang, Jian Tao Guo, Tong Lu Li
Abstract: In this paper, the deformations and the stresses of surrounding rock of Jijiata tunnel, Liulin County, Shanxi Province, are all computed before reinforcement and after reinforcement, through the 3D numerical simulation. According to the computing result, before reinforcement, the computing result of the lateral displacements of the surrounding rock is consistent with the field measurement result. The maximum principle stress and the minimum principle stress are all less than the strength of the surrounding rock supporting, and this will not cause material damage so as to structural damage. But, since the tension stress is higher than the strength of the junction of tunnel arch and tunnel upright wall, this leads the larger deformation and the failure of the junction. After reinforcement, through the steel arch and the lock pin bolt’s enhanced role, the lateral displacement of the tunnel can be constrained effectively, the maximum principle stress and the minimum principle stress can be less than the strength of the surrounding rock supporting, and the tension stress can also be less than the strength of the junction. All the structures are all stable after reinforcement. Thus, this method should be selected as the proper method to reinforce the tunnel.
1064
Authors: Bin Chen, Jiang Guang Liu
Abstract: A backfill clay method which is often adopted in small earth dam’ anti-seepage and reinforcement engineering has been introduced, and its using experiences in Zhejiang province, east of china, has been summarized. The design and construction process using the method has both been represented in the paper, with several technical difficulties had been selectively discussed. Application in hundreds of dams during the past decade showed that the method is characteristic of short working term, low cost, no need of many oversize machine, simple working technology and convenient application.
1370
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.
1135
Authors: Giovanni Cenci, Sabrina Cenci
Abstract: We illustrate the evolution of our systems for the restoration of old timber structures, devised to make up for the often operationally impractical purely theoretical concepts. These alternative systems are commonly accepted because they are effective and maintain the same readability as ancient knowledge did. We are using similar techniques to restore static conditions to damaged laminated timber structures, too.
1006
Authors: Alifujiang Xiamuxi, Akenjiang Tuohuti, Akira Hasegawa
Abstract: In numerical simulations of reinforced concrete (RC) columns with ADINA, when the REBAR element model is applied to simulate the reinforcement, the load-displacement curve of RC is similar to that of concrete, without reflecting the contribution of reinforcement. Therefore, employing another element model-BEAM element model for reinforcement, nonlinear analyses of RC columns are carried out and compared against the REBAR element model. The nonlinear analysis of reinforced concrete filled steel tubular (RCFT) columns, then, is performed with the BEAM element model. Meanwhile, the axial compression tests of concrete, RC and RCFT columns are also conducted to validate the nonlinear analysis. Comparing the results of nonlinear analysis against the results of experiment, it is concluded that the BEAM element model can simulate the reinforcement more reasonably than REBAR element model and can be applied to the nonlinear analysis of RCFT columns.
186
Authors: Kai Wang, Zhong Ming Xiong, Ni Peng
Abstract: As a new seismic technique, the input acceleration is reduced effectively by the isolation technology. The social benefit of seismic isolation technology has been proved, but the economic effect still remains an insufficient understanding. Regarding that, this article take the actual projects as the background to analysis the isolation structure’s economic effect qualitatively, summed up a selection criteria of the isolated structure, lays a foundation for the promotion and application of the isolation technology
505
Authors: Zuo Yun Mei, Chuan Qing Liu, Xing Mi, Ping Wu
Abstract: A new reinforcement measure with no-fire operation is presented, which is very suitable for space trusses which are located in gas stations. A finite element model (FEM) is presented with shell elements and multipoint constraint elements. With this FEM, nonlinear analyses are carried out. Analytical results show that integral failure of reinforced pipe is caused by yielding of original pipe inside. So it is not necessary to reinforce original pipe using steel pipe bonded outside with high yield strength. With the increase of length of bonded pipe outside, loading according to elastic stage and ultimate bearing loading increase, it is clear that the length of bonded pipe outside is an important factor which influences the bearing capacity.
401
Authors: Hrusikesh Nath
Abstract: The in-situ synthesis of ceramic particles in Al-matrix composites gives an uniform and homogeneous microstructure. The matrix reinforcement interface is compatible with the matrix, interface is clean and provides good interface bonding. The evenly distributed sub micron sized reinforcement particles in Al-matrix enhances the strength and toughness of the composite. The formation of particle clusters and agglomerations are minimized or eliminated by suitably choosing the in-situ process parameters. Large particles and agglomerate are easily fractured where as evenly distributed fine particles are resistant to crack propagation and improves the strength of the composites. The problem encountered with the formation of secondary intermetallic Al3Ti and Al4C3 phases are addressed.
287
Authors: Simona Cavalu
Abstract: The history of acrylic bone cement comprise a long period of time, Sir John Charnley being considered the founder of modern artificial joint replacement, as he started to develop the cementing in the late 1950s. Acrylic bone cements (ACB) are polymer-ceramic composites based on polymethyl metacrylate (PMMA), widely used in orthopaedics as suture materials and fixation devices. The main features of these materials are: 1) biocompatibility and ability to support new bone growth (osteoconductive) and 2) bioactivity (ability to form a calcium phosphate layer on its surface). The main function of the cement is to serve as interfacial phase between the high modulus metallic implant and the bone, thereby assisting to transfer and distribute loads. During years of follow up, cemented prosthesis with acrylic bone cements (ABC) demonstrated a good primary fixation and load distribution between implant and bone, along with the advantage of fast recovery of the patient. However, several problems are still persisting, as the orthopedic acrylic bone cements have to meet several medical requirements, such as low values of maximum cure temperature in order to avoid thermal necrosis of the bone tissue during the setting time, appropriate setting time (so that cement does not cure too fast or too slowly) and high values of compressive strength in order to withstand the compressive loads involved by normal daily activities. Generally, the improvement mechanical properties can be realized in three directions: 1) by searching alternative material to PMMA acrylic bone cements; 2) chemical modification of PMMA; and 3) the reinforcement of PMMA by adding different bioactive particles, antimicrobials, vitamins. The aim of this rewiew is to explore the development of bone cements in the last decade, to highlight the role of bone cement additives with respect to mechanical properties and limitations of polymethylmethacrylate in orthopaedic surgery. The behavior of antibiotic-loaded bone cement is discussed, compared with other alternative additives including nanofillers, together with areas of research that are now open to explore new insights and applications of this well known biomaterial.
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