Advanced Materials Research Vols. 243-249

Abstract: Based on a 3-D solid finite element parametric model, an optimization design method of reinforced concrete aqueduct with multi-longitudinal beams is proposed. In this method, the stress of sidewall and subplate is controlled by the sectional crack-resisting criteria, the space between longitudinal beams or crossbeams is decided by the coordination of structural deformation, and the bottom stress of longitudinal beams or crossbeams is restrained by the nominal tensile stress. Taking the lightest dead weight of aqueduct as the objective of optimization, this method is able to give the optimal sizes and distribution patterns of the main load bearing members. The internal force of each structural element of the optimized aqueduct is calculated by a 3-D beam-shell finite element numerical model and thus the reinforcements are arranged. Compared with the prototype, the optimized aqueduct shows the advantages of lighter weight, more reasonable stiffness distribution, coordinated deformation and economical reinforcements.

Abstract: Perma-Zyme is an enzymatic stabilizer. To test the feasibility of adding Perma-Zyme to tabia used to protect ancient earthen ruins, the 28d unconfined compression strength, permeability and color-difference were tested to determine the difference between the tabia and tabia treated with Perma-Zyme. The experimental results show that the 28d unconfined compression strengths of specimens treated with Perma-Zyme are higher than those without Perma-Zyme, and the color-difference(DE^*) between the tabia and tabia mixed Perma-zyme is larger than 3(suggested color tolerance Chinese standardized GB/T 15608-2006), and the permeability coefficient of tabia mixed Perma-Zyme is smaller than that without Perma-Zyme, i.e., has better impermeability. Box dimension values of SEM images(with different scale bars) of samples were computed by box-counting method. Box dimension values of SEM images of the same sample are different on different scale bars. The analysis shows that SEM microstructure of the tabia sample treated with Perma-Zyme is finer and denser than the one without Perma-Zyme.

Abstract: Former approaches for designing reinforced concrete aqueduct with multi-longitudinal beams were mostly based on experience. In this study, an optimization method is proposed instead. According to the mechanical characteristics of aqueduct, optimization principles for structural deformation coordination and sectional crack-resisting are developed. Furthermore, in optimization of large and complex reinforced concrete aqueduct, this method employs nominal tensile stress to control the maximum crack width. In addition, a 3D beam-shell element model is suggested for calculating internal force of aqueduct.

Abstract: In order to clear mechanical design of corner joints, it is necessary to further investigate mechanical property of corner joint in gabled frames. Through relevant requirements of the existing cause and ANSYS finite element software analysis, contrasting. Some conclusions are given in the article. The analysis results show that setting stiffener in the line of inside and outside corner folded point is necessary and simple. Meanwhile, the calculation formula is given.

Abstract: In order to clear constructional design of corner joint, it is necessary to further investigate mechanical property of corner joint in gabled frames. Through static test of comparing the panel zone with and without inclined stiffener. Some conclusions are given in the article. The load displacement curves show that the capacity of oblique nodes installed within stiffening rib components is enhanced i.e.40% more than those without stiffening rib nodes. The results reveal that in the gabled frames, the corner node with the inclined stiffening rib can improve the bearing capacity of the specimens. When the extraterritorial flange is tension, the erection of the inclined stiffening rib can prevent structural failure and improve effectually the ductility of the structure.

Abstract: One of the most popular pre-reinforcement structures in the construction of tunnels through weak grounds would be the pipe roof reinforcement. This composite structure consists on installing, prior to the excavation of a length of tunnel, a series of pipes, either parallel to the tunnel axis or at a certain angle with it. By injecting grout through the pipes, the ground in between the pipes is stiffened and the pipes are connected, creating a kind of ‘umbrella’ above the area to be excavated. In this paper, by modifying the upper bound solution for tunnel face stability, the three-dimensional model for expressing the tunnel face stability with pipe roof reinforcement was established. For a typical example, the solutions computed by the proposed approach were compared with the results given by wedge model, trapezoid wedge model and centrifugal-model test to verify the reasonability of the method. It is shown that the calculation results of limit analysis are in close agreement with test results.

Abstract: There have been few researches on the reliability of prestressed steel structure, especially the study on the reliability considering the failure of key components. In order to study the impact of the component failure on the structure reliability, the response surface method based on central composite design is adopted and APDL language is applied to write a corresponding program, thereby carrying out reliability calculation and analysis to the model. The system reliability and parameters sensitivity of the beam string structure under different failure of components are provided. The results indicate that the impact of cable failure on the reliability is large, but it is weak by the failure of brace rod. The results may serve as a reference for the health monitoring and safety assessment of the prestressed steel structure.

Abstract: Microvibration is one of the key factors affecting the normal operation of a microelectronic plant. Such measures as to increase the stiffness or damping ratio to prevent microvibration are easy to implement and low in cost. By using the finite element analysis software Sap2000 to simulate the microvibration performance of the working platform of a typical microelectronic plant, this paper compared some of its microvibration response when there were shear walls with that when there were no shear walls, discussed efficiency of structural stiffness on its microvibration response. The results indicate through the provision of shear walls to increase the stiffness of working platform enlarge acceleration and velocity response of the structure, it can decrease displacement effect.

Abstract: According to the thought of engineering optimization and the theory of composite structure design, the minimum of the project cost and the maximum of the diagonal shear capacity are taken as the optimization objectives whose importance can be adjusted by weighting factors and the linear weighted method is used to establish evaluation function which changes multi-objective into single-objective in optimization. Taking the various constraints into consideration and choosing the sensitive design variables, the mathematical model of the multi-objective optimization design for steel reinforced high-strength concrete beams is provided. Based on the optimization thought of the Complex Method, the nonlinear optimization problems are solved by MATLAB program.

Abstract: Based on the experiments of 4 SRHSC (steel reinforced high strength concrete) column specimens, which were different in concrete strength, axial compression ratio and spacing of hoop reinforcement, this paper investigates the seismic behavior and flexural strength of SRHSC columns under cyclic lateral loading which is controlled by the displacement. According to the date and phenomenon of experiment, adopting existed theory and foreign codes for composite columns, the failure mode, lateral load-deflection relationship, strength and stiffness deterioration, ductility capacity and energy dissipation capacity of SRHSC columns is analyzed.