Advanced Materials Research Vols. 378-379

Abstract: Aimed at main factors influencing the safety of super-large deep foundation pit, a safety monitoring system combined with technologies of modern compute, network, image-video transmission and GPS satellite positioning was designed in this paper. The system is effective in rapid, precise data collection, scientific analysis, giving feedbacks, sharing information between different departments using different sources of monitoring data and other related information. It can provide security for construction of foundation pit, and valuable for foundation pit design and construction technology advancement.

Abstract: This paper analyzes the magnetoelastic response of type-II superconducting film. Cracks can lead to large local current enhancement near the crack-like flaw tips, Based on the previous work, the effects of the flaw on the stress field are discussed. It is found that the presence of the flaw markedly enhances the concentration of the stress near the tips of the flaw. In addition, as the geometry increases, the position where the maximum stress occurs increases.

Abstract: Sound barriers are widely used as an important engineering measure to mitigate traffic noise pollution in urban elevated roads. However, structure design codes on sound barrier used in urban viaduct is empty, which is a key reason for the short service life of sound barrier. Numerical simulation of characteristics of running cars induced wind loads on sound barrier of elevated roads is carried out based on the method of computational fluid dynamics. The changing course of wind loads on the surface of sound barrier is reappeared in the process of cars passing by the sound barrier. The distribution rule of wind loads on the surface of sound barrier at different space positions is revealed. Influence factors of wind loads on surface of sound barrier are discussed by parameter analysis. The conclusions shows that running cars induced wind loads on sound barrier of elevated roads should considered as one main design loads, especially for the anti-fatigue design of steel columns of plate-inserted sound barrier.

Abstract: The explicit dynamic code LS-DYNA3D is used to simulate limited-thickness concrete slabs penetrated and perforated by steel projectiles with velocities from 381 m/s to 1058 m/s. The concrete slab is modeled with Smooth Particle Hydrodynamics (SPH) elements near the trajectory while Finite Element Method (FEM) elements in the others of the target, which is called FE-SPH method. The elastic-plastic model and Johnson-Holmquist concrete model are used to describe the mechanical behaviors of the projectiles and target slabs, respectively. The residual velocities computed by both FEM and FE-SPH method agree well with those of experimental results. For brittle concrete, the penetration and perforation phenomenon modeled by FE-SPH are in closer agreement with the experimental results than those modeled by FEM. Simulation of penetration and perforation by FEM require artificial element erosion set, which would lead to distortion of modeled results.

Abstract: The concrete containing expansive agent, when limited, is affected by the addition of expansive admixture much, which influence the carbonation resistance. This article makes a comparison with anti-carbonation ability of concrete under restraint and non-restraint condition. The compressive strength and carbonation depth are tested, and the changes of micro-structure are also analyzed with TG-DSC and MIP analysis. The results reveal that single-dimensional restraint condition can efficiently improve the pore structure of concrete. And expansive agent also has a slight improvement to it. Single-dimensional restraint condition can obviously enhance the anti-carbonation ability of concrete containing expansive agent.

Abstract: In the current paper, three different constitutive models are employed for the analysis of laminar MRF (MagnetoRheological Fluid) flows between two parallel plates. The capability of a recently constructed non-convex constitutive model is compared with those of widely used Bingham model and Herschel-Bulkley model. The comparison among simulated flow velocity distributions and shear stress - shear strain rate characteristics based on different models is presented. It is shown that the non-convex consitutive model outperformance the other two models.

Abstract: Understanding the relationship between amino acid sequences and folding rates of proteins is an important challenge in computational and molecular biology. All existing algorithms for predicting protein folding rates have never taken into account the sequence coupling effects. In this work, a novel algorithm was developed for predicting the protein folding rates from amino acid sequences. The prediction was achieved on the basis of dipeptide composition, in which the sequence coupling effects are explicitly included through a series of conditional probability elements. Based on a non-redundant dataset of 99 proteins, the proposed method was found to provide an excellent agreement between the predicted and experimental folding rates of proteins when evaluated with the jackknife test. The correlation coefficient was 87.7% and the standard error was 2.04, which indicated the important contribution from sequence coupling effects to the determination of protein folding rates.

Abstract: For general damped linear systems with multiple eigenvalues, this study provides a practical step-by-step procedure of the high-order dynamic response analysis. The method derived in this study has clear physical concepts and is easily to be understood and mastered by engineering designers. Moreover, a numerical example is used to analyze the correctness and the effectiveness of the new method by comparing the calculation results with the theory solution.

Abstract: The algorithm idea of virtual boundary element collocation method with RBF interpolation on virtual boundary and diagonalization feature in fast multipole method is presented to study 2-D elasticity problems in this paper. In other words, the new fast multipole method (FMM) adopting diagonalization and the generalized minimal residual (GMRES) algorithm are jointly employed to solve the equations related to virtual boundary element collocation method (VBEM) with RBF interpolation on virtual boundary. In this paper, the numerical scheme suitable for original FMM with respect to two-dimensional problem of elasticity is optimized, through the introduction of concept of diagonalization, in terms of the radial basis function to express the unknown virtual load functions, in order to further improve the efficiency of the problem to be solved. Then large-scale numerical simulations of elastostatics might be achieved by the method. Numerical examples in the paper have proved the feasibility, efficiency and calculating precision of the method.

Abstract: Based on the modal superposition and dynamic programming theory, a method is proposed to identify bidirectional moving forces from orthotropic plate bridge responses in time domain. The bridge deck is modeled as an orthotropic plate and the moving vehicle loads are modeled as two groups of axle loads moving cross the bridge deck in two opposite directions. The equation of motion is formulated in state space and the resulting damped least-square identification problem is solved using the dynamic programming method with regularization on the solution. Some numerical simulations show that the proposed method is effective, accurate and suitable for the bidirectional moving vehicle load identification. Some parameter effects of measurement noise and of eccentricity of moving loads on the identification accuracy are discussed as well.