Punching shear failure of slab-column connections can cause the progressive collapse of a structure. In this study, a punching test database is first established. Then, based on the Levenberg–Marquardt (LM) algorithm and using the nonlinear function of the backpropagation neural network (BPNN), a prediction model of the punching capacity of slab-column connections without transverse reinforcement is established. Finally, the proposed model is compared with the formulas of the Chinese, American, and European standards using several methods. The statistical eigenvalue method shows that the BPNN model has the highest accuracy and the lowest dispersion. The defect point counting method shows that the BPNN model had the fewest total number of defects and was the safest and most economical. The influencing factor analysis suggests that factors in the BPNN model had the most reasonable influence on the punching bearing capacity of slab-column connections. Finally, the model is verified using a case study and the Matlab program. The results show that the average error of the formulas in the Chinese, American, and European standards are 21.08%, 30.21%, and 11.47%, respectively, higher than that of the BPNN model.
Abstract. The progressive collapse of structures under accidental actions is a serious threat to the public safety. Numerical analysis of a 2x2-bay and single-story reinforced concrete flat plate frame model is done in this paper, the time of failure and the position of failure column are taken into account. It can be found that the Dynamic Amplification Factor (DAF) increases with the decrease of failure time, the DAF under compressive membrane action is less than the stage of the tensile membrane action and the compressive membrane action is more important to avoid progressive collapse. When the time of failure is not changed, the DAF is negatively correlated with the load under compressive membrane action and the DAF is positively correlated with the load under tensile membrane action.
Abstract. Under blast load, the progressive collapse performance of reinforced concrete structures is very complex. This article gives a more applicative and efficient RC frame structure model by ANSYS/LS-DYNA, and studies the effects of concrete strength and longitudinal reinforcement ratio to progressive collapse performance by parametric analysis, then calculates the critical load and dynamic amplification factor. It is found that the progressive collapse resistant capacity can improve with the concrete strength and longitudinal reinforcement ratio, the critical load of the frame structure is 3.15 times of the design load, and the dynamic amplification factor is 1.32.
Abstract:The design and construction level of power grids are increasing rapidly with the development of China's power industry. The tower of Transmission line has become an important forced fulcrum. Safety and economy are basic requirements of conventional structural design. However, making the transmission lines and the environment in harmony and unity challenges structural designers. In this paper, a new-type transmission tower--bamboo transmission tower is designed and researched on the basis of a practical project. It can be found that the new-type of transmission tower makes the tower and the environment in harmony and unity when it meets the safety and economy requirements.
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