Applied Mechanics and Materials Vols. 94-96

Abstract: To better solve the problems of local buckling and stability of thin-walled concrete-filled steel tubular short columns and improve the ability of specimens’ overall deformation, long or short binding rebars were set up and anchored on the inner surfaces of the steel tubes; meanwhile the static load test was performed. The results show that the main factors affecting the bearing capacity are steel pipe wall thickness, concrete strength, binding rebars in turn and the ductility is concrete strength, binding rebars, wall thickness. Long or short rebars also significantly improve the deformation properties of specimens. Taking the common specimens’ average ductility factor of 2.30 as a benchmark, the average factor of specimens configured with short rebars is 2.85, increased by 24% and configured with the long is 3.34, increased by 45%. Deformation properties of the specimens substantially increase and security of the structure enhances after setting up rebars.

Abstract: Guided wave tomography has shown great potential for quantitative nondestructive evaluation in structural health monitoring. An improved simultaneous iterative reconstruction technique (SIRT) combining genetic algorithm (GA) is presented in order to improve image quality of guided wave tomography. The simulated reconstructed images of flawed plate and pipe using usual SIRT and improved SIRT methods have been compared quantitatively and qualitatively.

Abstract: Abstract.The seismic properties, failure characteristics and lateral load-deformation curves of the three specimens were investigated by testing two specimens retrofitted with CFRP(carbon fiber reinforced polymer)sheets(fabrics) and one specimen without any attachments and by attaching CFRP sheets to the two specimens in two ways. At the same time , the strain level in CFRP sheets on one of specimens was investigated. It came to the conclusion that CFRP sheets were able to improve the seismic properties of concrete hollow block structures significantly and the patterns in which CFRP sheets were attached to structures were a dominating factor influencing retrofit effects. The equations for the shear carrying capacity were presented by introducing a truss model. The validation of the equations was made by contrast of computed values and observed ones and it can be used as a reference to design retrofitted structures.

Abstract: The technology of strengthening RC beam with CFRP sheets is now a hotspot of research in civil engineering. The FEM analysis was made for the whole deformation course of the flexural behavior of RC beam with CFRP sheets on lateral side, and the result was coincided with the experimental results.

Abstract: This paper compares the flexural bearing capacity, rigidity, and ductility of the reinforced RC beams after comparative tests of reinforcing RC beams by three different ways: directly bonding CFRP, bonding CFRP after replacing concrete and bonding CFRP after replacing concrete and planting bar. The results show that the method of replacing concrete can sufficiently avoid the debonding between CFRP and concrete, improve the flexural bearing capacity, and further strengthen the rigidity and ductility; whereas the method of planting bar can well guarantee the bond of Young and old concretes, let the replacing concrete together with CFRP work better, and carry capacity increase in reinforcement.

Abstract: Microseismic will produce when rock mass break. The occurrence of microseismic monitoring has close relationship to the energy release and crack's evolution in the rock mass. Therefore the microseismic monitoring can be used to predict the future rupture of the rock mass. MS location is the base of this prediction. The method of solving locating equation and the stability of answer are the key matter of microseismic monitoring applications in engineering fields. This paper uses Gauss-Newton iterative method to solve locating equation in order to advancing the precision and stability of answer and reducing the calculation workload. Based on the optimization toolbox of Matlab, the non-linear locating equations are solved and the visible locating results of microseismic are achieved.

Abstract: Using the theory of nonlinear elastic mechanics and fracture mechanics, the equation of motion governing equation of cracked beam is derived by the energy method, and solved with separation method of variables. Vibration analysis method based on the energy principle in this paper is proved feasible.Through numerical analysis, the effects of structural damping, crack location and depth on natural frequencies of linear vibration is investigated.

Abstract: In the smoothed particle hydrodynamics (SPH) method, the particle inconsistency problem significantly influences the calculation accuracy. In the present study, we investigate primarily the influence of the particle inconsistency on the first derivative of field functions and discuss the behavior of several methods of addressing this problem. In addition, we propose a new approach by which to compensate for this problem, especially for functions having a non-zero second derivative, that is less computational demanding, as compared to the finite particle method (FPM). A series of numerical studies have been carried out to verify the performance of the new approach.

Abstract: Restrained torsion analysis of open thin-walled beam is presented in this paper. A finite element model is developed. The element is based on the first-order torsion theory, which accounts for the warping deformation and shear deformation due to restrained torsion. The interpolation functions of total rotation and twist rate of free warping rotation of cross section are constructed respectively by using the relationship between these two rotations. Numerical example is illustrated to validate the current approach and the results of the current theory are compared with those obtained from classical Vlasov theory and first-order torsion theory.

Abstract: An atomic scale modeling method is provided to study the buckling behavior of the single-walled carbon nanotubes. The Brenner potential is employed to describe the C-C atomic interaction,and the stable state is determined using the Norton’s method with the first- and second-order derivatives of the total energy with respect to the atomic coordinates. The reponse of single-walled carbon nanotubes under the axial compressive, twisting and buckling loads is modeled using the developed Fortran codes, and the buckling patterns are obtained. The proposed method can be used to study the mechanical property of cabon nanotubes and explore its application in the cement composite in future.