Applied Mechanics and Materials Vols. 166-169

Abstract: The mass-normalized stiffness matrix of the star spring-mass system is an arrowhead matrix. Given two eigenpairs of the arrowhead matrix. It is assumed that the total mass of a star spring-mass system is known. The problem of constructing the physical elements of the system from the known data is considered. The necessary and sufficient conditions for the construction of a physical realizable system with positive mass and spring stiffness are established. If these conditions are satisfied, the system may be constructed uniquely.

Abstract: This paper deals with the evaluation of response variability of composite plates due to randomness in the Poisson’s ratio in particular for the out-of-plane behavior. To this end, we adopt the weighted integral stochastic finite element (SFE) scheme and derive a SFE formulation employing Taylor’s expansion on the random Poisson’s ratio and displacement vector as well. In case of composite plates, the stiffness of the structure is affected by the stacking scheme of individual layers. This means that even the plates subjected only to in-plane loading can show out-of-plane behavior. In order to investigate this phenomenon, we chose two example plates with symmetric and asymmetric stacking scheme. A detailed explanation on the results is addressed for the plates under consideration.

Abstract: Residual thrust method is an original method for slope stability analysis in China. It is widely used in industrial and civil construction as well as the ministry of railways of China, especially in the analysis and treatment of slope stability of the landslide. For the existing remained slip force method, this paper briefly describes how to use residual thrust method to analyse the stability of side slope, and it gives a brief account of residual thrust method formula and its solution. Moreover, this paper outlines the applicability of the residual thrust method and still existing problems and some corresponding improvement methods those have been successfully applied to practical project.

Abstract: In this paper, the scattering problems of SH waves on periodic cracks in an infinite of piezoelectric/piezomagnic composite materials bonded to an infinite of homogeneous piezoelectric materials is investigated, the Fourier transform techniques are used to reduce the problem to the solution of Hilbert singular integral equation, the latter is solved by Lobotto-Chebyshev and Gauss integral equation, at last, numerical results showed the effect of the frequency of wave, sizes and so on upon the normalized stress intensity factor.

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Abstract: In this paper, some factors effect on the maximum stress of inner rubber of some elastomer isolators with big diameter of 1500mm are analyzed by FEA. These factors include size of hole, ratio of , shear modulus of inner rubber , the first shape factor , thickness of cover rubber. The isolators include those used in building or bridge, loading condition is single compress . Research results show that size of hole, ratio of and have a little effect on the maximum stress of inner rubber, but shear modulus of inner rubber, and thickness of cover rubber hardly effect.

Abstract: A new method based on dynamic response sensitivity is proposed for the identification of local linear time-varying (LTV) system. The unknown local LTV structural stiffness is modeled by orthogonal polynomial approximations, and the sensitivities of structural dynamic response with respect to orthogonal coefficients are derived. The identification equation is set up based on Taylor’s first order approximation, and is solved with the damped least-squares method. A fifteen-story shear building is studied to validate the proposed method. Three ideal cases of LTV systems, with periodically, abruptly and randomly varying stiffness at the 8th story of the structure, are investigated to illustrate the capability of the algorithm to track the variations of the systems. Numerical simulation with noisy measured accelerations shows that the proposed method can accurately identify various kinds of local time-varying system from only several responses of the structure. This method provides a new approach for detecting local time-varying stiffness of structures with incomplete measured output information.

Abstract: A nonlinear analysis program based on fiber model was developed and used in analyzing the flexural behavior of steel reinforced concrete (SRC) columns under axial and bilateral loading. Concrete different confinement levels for different zones in a SRC column section, such as cover concrete zone, stirrup confined concrete zone and steel confined concrete zone, etc., can be considered. Some SRC tested specimens were simulated using the developed program. It was pointed out that the flexural capacity will be lower-estimated if the concrete confinement was neglected.

Abstract: For the distortional buckling of cold-formed thin-wall steel members, the Direct Strength Method (DSM) is a recently adopted design approach by foreign standard, and Chinese professional standard Technical specification for low-rise cold-formed thin-wall steel buildings present the calculation formulas based on the Effective Area Method (EAM) .The key of both methods is the elastic distortional buckling stress .At present, the calculation methods about it are over conservative .Compare the calculation results of method in AISI S100with the one calculated by software CUFSM ,for C and Z sections in bending and axial compression loading respectively in the North American Specifications for Cold-Formed Steel Structural Members (AISI S100). This paper presents revised simplified methods for calculating the elastic distortional buckling stress. The new methods yield more accurate results but similar computation cost compared to the existing methods.

Abstract: Given the odd /even degree eigenpair and the even degree eigenpair of a simply connected central symmetric spring-mass system respectively. The inverse mode problem of constructing the physical elements of the system from two eigenpairs and the total mass of the system is considered. The necessary and sufficient conditions for constructing of a physical realizable system with positive mass and stiffness elements are established. If these conditions are satisfied, the simply connected central symmetric spring-mass system may be constructed uniquely. The numerical methods and examples are given finally.