This study is aimed to analyze the characteristics of different kinds of time-of-flight diffraction (TOFD) images for welding seam defects. Combined with t

The dynamic loads acting on concrete-filled steel tubular members under axial impacts by rigid bodies were studied herein by FEM. The whole impact process was simulated and the time history of the impact load was obtained. The effects of eight factors on the axial impact load were studied; these factors were the impact speed, mass ratio, axial pressure ratio, steel ratio, slenderness ratio, concrete strength, impact position, and boundary conditions. Besides this, the effects of concrete creep on the impact load were also considered by changing the material parameters of the concrete. The results show that axial impact load changes with time as a triangle. The peak value of impact load increases and the impact resistance improves with the growth of the axial pressure ratio, steel ratio, slenderness ratio, and concrete strength after creep occurs. As the eccentricity of the axial impact acting on a concrete-filled steel tubular member increases, the peak value of the impact load decreases. The enhancement of constraints at both ends of the member can improve the impact resistance. The creep reduction coefficients for the peak axial impact load of a concrete-filled steel tubular member under axial compression and considering the creep effect over 6 months and 30 years are 0.60 and 0.55, respectively. A calculation formula for the peak value of impact load was suggested based on the existing formula, and its accuracy was proved by finite element calculation in this study.

In this paper, the “battery” program was compiled based on the parametric tool Rhino+Grasshopper and the parameterized modeling function of K-type single-layer spherical reticulated shell structure was realized. At the same time, based on BP neural network algorithm and considering the complex mapping relationship in nonlinear analysis, a neural network model and program was established to predict the ultimate bearing capacity of K8 single-layer spherical reticulated shell structure. The results show that the program can realize the modeling process efficiently and the reliability of the neural network to predict the ultimate bearing capacity of single-layer reticulated shells is verified, which provides an effective tool for improving the parametric modeling and structural optimization of single-layer reticulated shell structure.

With the continuous development of blasting technology, it has been widely used in various construction projects. While bringing convenience to construction, it also has a series of negative effects on surrounding buildings (structures), especially the negative effects of blasting vibration on buildings (structures), which has been paid close attention by scholars at home and abroad. For blasting vibration on the dynamic response of the gravity dam to produce, this article adopts the method of numerical simulation, the finite element software ANSYS is applied, the numerical calculation model of concrete gravity dam is established and the dynamic time-history analysis is calculated, in the different blasting conditions, the blasting vibration on the dynamic response of gravity dam is obtained, the calculation and analysis results as basis is supplied for the selection of the blasting vibration monitoring part of the gravity dam.