Advanced Materials Research Vols. 243-249

Abstract: The research of fatigue crack threshold is an issue in fatigue research. Though there are many research methods, calculation formulae and test data, most of the formulae are evaluated by experiments and have test constants in them, which lead to inconvenient application. Based on displacement fields around crack tip and fatigue theory, A formula that can describe fatigue crack threshold related to material properties is proposed. Each parameters in the formula has definite physical meaning. And it is convenient to use this formula. Using this formula, the material threshold is primarily calculated before design. At last, using existing data to verify, it is shown that the formula is reliable.

Abstract: Based on the construct detail, structural behavior of cellular voided slab was analyzed. Differential equilibrium equations and formulae of flexural and torsional stiffness of the cellular voided slabs were given. Solution of deflection of cellular voided slabs fixed supported by four edges were presented by numerical simulating method. Analysis and comparison by elastic finite element method on three group ensamples were carried out. The errors in numerical solutions to finite element method analysis results are little; the solution of deflection was applicable to solve cellular voided slabs fixed supported by four edges.

Abstract: Giant magnetostrictive materials, such as Terfenol-D, have been used to make a principal driving element in actuator, owing to its fine characteristic that is large strain, high energy density, small hysteretic loss and less performance degradation in room temperature. With the discovery and refining of Terfenol-D, the magnetostrictive actuator has gotten great development for recent twenty years. The free vibration and forced vibratin of linear magnetostrictive actuator is analyzed. The initial state of rod is at rest. The computational results show that the displacement response is synchronous with the current.

Abstract: This paper presents three-dimensional numerical simulation of UHPFRC-NSC composite beam with Diana. An elastic-plastic fracture model is proposed to describe material properties of UHPFRC. Differing from other concrete constitutive model, this one considers strain hardening in tension because of characteristic of UHPFRC. A total strain rotating crack model is used to describe material properties of NSC. The results of relevant push-out tests are used to describe the shear force-slip relationship of shear connection between UHPFRC girder and NSC slab. The numerical investigation focuses on the evaluation of load-deflection behavior, failure mode and shear connection. The agreement of test results and numerical results indicates the reliability of model.

Abstract: An economic and safety design proposal of the spatial grid structure is very difficult to find according to traditional design method.The group search optimization and its improved algorithm are applied in optimization design of a spatial grid structure in this paper. In this paper the finite element model of the spatial grid structure is firstly built through the platform of ANSYS. Then based on the parameterized programme language ADPL of ANSYS ,the group search optimization (GSO) and the quick group search optimization(QGSO ) are compiled ,the optimization analysis of the spatial grid structure are carried out. Finally, the optimization results and the optimization one from ANSYS are compared. It show that the optimization methods hereinbefore are feasible and the design proposals of them are better than the one of ANSYS.

Abstract: With the generalized displacement parameters of spline knots chosen as basic unknowns, the node displacement functions of spatial mega frames were built up, then element node displacements could be expressed by these parameters. New stiffness equation of spatial mega frame was deduced according to energy variational principle. The nodal displacement and nodal forces were worked out by the displacement parameters of spline knots. Process of block assembling for spline-discretization matrix was introduced briefly. One spatial mega frame was calculated by QR method and different finite element softwares. Comparation among the results and those of references proves that QR method is exactly an economical, effective and reliable method for computation of spatial mega frames. It provides a new approach for simplified calculation to spatial mega structures, so has good theoretical and practical value.

Abstract: Silica Fume Concrete (SFC) produced with hybrid Fibres is a relatively new and advanced material of construction. In a typical SFC with Hybrid Fibers mixture consist of absence of coarse aggregate replaced by fine sand in conventional concrete. The Portland cement plays the role of fine aggregate and the silica fume that of the cement. SFC has no large aggregate and contains small steel Fibers that provides additional strength and in some cases can replace traditional reinforcement. The strength and ductility characteristics of SFC may be improved by using hybrid Fibers. The different combinations of hybrid Fibers like (Steel + galvanized iron) (Steel + polypropylene) (Steel + Waste coiled steel Fibers) (Steel + HDPEF) can improve the characteristics properties of SFC. In this paper, the experimental investigation has been made to study effect of chloride attack on the strength properties of SFC using Hybrid Fibers like Compressive Strength, Tensile Strength, Flexural Strength and Impact Strength. Results are compared with strength properties of SFC without Fibers and SFC with Mono Fibers.

Abstract: In this study an attempt has been made to find the suitability of the ceramic waste mud as a possible substitute for conventional concrete. Experiments were carried out to determine the flexural and compressive strengths of concrete and the modulus of elasticity of mortar with various activators. The result indicated that cement could be partly replaced by ceramic waste mud. The strength of concrete verious as the activator changed, so the key to increase the strength of concrete is to find the proper activor.

Abstract: This article particular introduce the double-shear wall template installation construction technology, construction points, construction quality control, safety precautions and the mode of material saving, which is a commercial bank’s integration business building underground vault with a special requirement. Making the construction step, the construction point and inspecting, in accordance with the construction method, construction point, construction procedure, methods of the materials processing, quality criterion, safety measures, materials saving measures, is not only to meet the usage function of the design requirements and requirement of the project quality, but also to save material,achieve the purpose of cost reduction.

Abstract: In order to improve mixing quality of asphalt mixture, a method of theoretical analysis and test was used to analyze the effects of negative pressure of drying drum, geometric parameters of mixer and aggregate variation ratio in hot aggregate bins on the segregation of asphalt mixture. Reasonable measures of controlling segregation in the mixing process were given out. Research results indicate that stable negative pressure of drying drum reduce the temperature segregation of asphalt mixture by controlling temperature undulation of hot aggregate and reasonable arrangement of mixing blades cut down material segregation of asphalt mixture with adequate mixing. That isn’t all, delivery proportion of the aggregate in hot aggregate bins and mesh size of vibrating sieve, properly selected according to the gradation of cold aggregate, improve quality and efficiency of asphalt mixture with lower aggregate variation in hot aggregate bins.