Search

The radial gate corbel beam is a kind of gate support structure more often used in large and medium-sized reservoirs, but the current corresponding structural design code does not give a review calculation method for it. Because there are obvious differences between a corbel and a corbel beam in structural form and force, if the corbel beam is just simplified in the calculation as a corbel structure, it can easily lead to misjudgment of insufficient bearing capacity. This misjudgment has a significant impact on later safety assessment, danger removal, and reinforcement. Currently, there are limited studies available on the internal stress distribution of the corbel beam. In this study, taking the danger removal and reinforcement of the radial gate beam of a medium reservoir in Beijing as an example, the concrete quality of the dam was tested by the core drilling method, and two safety review methods of the corbel beam for different types of reservoirs were proposed in combination with the Code for Design of Hydraulic Concrete Structures (SL191-2008). Then, three different types of calculation model were established by the method of theoretical mechanics calculation and finite element simulation. Combined with the safety test data, the stress state of the combined stress structure of the corbel beam and gate pier under the real state was analyzed and the safety evaluation was carried out. The calculation results of these two corbel beam safety review methods were respectively reduced by 32% and 47% compared with the current calculation method. Engineering practice has proved the rationality of the two safety evaluation methods proposed in this paper, which can provide a certain reference for similar engineering reinforcement. [ABSTRACT FROM AUTHOR]

Rail transit plays a very important role in the social and economic development of big cities. Its operational safety is of great significance for ensuring people's lives and maintaining social stability. In this paper, the rail transit operation safety management framework is proposed and analyzed by considering the factors of organizational management, personnel management, equipment and facilities and operating environment together. Considering the fuzzy uncertainty in the process of the safety assessment of rail transit operation (SARTO) and the interrelationship and conflict among the criteria, a new hybrid model combining DEMATEL, ANP and VIKOR with type-2 fuzzy linguistic variables is proposed. The model can present the effect-cause relationship among the different main criteria by the type-2 fuzzy DEMATEL, obtain the weights of the sub-criteria by the type-2 fuzzy ANP and the risk assessment value of each metro line by the type-2 fuzzy VIKOR and give further suggestions for rail transit operation safety management. This novel hybrid methodology is used to evaluate operation safety of metro lines in Beijing, and the sensitivity analysis is also applied to analyze the robustness. For the accuracy and consistency with the actual situation check, the proposed type-2 fuzzy VIKOR method is compared with both TOPSIS method and MOORA method in interval type-2 fuzzy sets. The application of Beijing metro lines proves the feasibility and the practicality of the new hybrid method, which provides effective support for decision-makers in practice. • Propose the index system on safety assessment of rail transit operation (SARTO). • Propose new hybrid model combining DEMATEL, ANP and VIKOR with type-2 fuzzy linguistic variables. • Evaluate the operation safety of six metro lines in Beijing using the proposed hybrid methodology. [ABSTRACT FROM AUTHOR]

Road safety conditions in China have worsened following rapid urbanization and motorization. For a long time now, China has ranked first in the world in the number of road accidents and fatalities. Therefore, evaluating safety levels is essential to implementing effective countermeasures. For developing countries like China, however, assessing safety levels via crash data statistical analysis is difficult because of limitations on a short history of collecting crash data, small samples and an incomplete collection of information. To address these limitations, the method of surrogate safety analysis using the traffic conflict technique (TCT) has become a widely used evaluation procedure. On the basis of the mechanism analysis of TCT, the paper presents a conflict hazardous assessment model (CHAM) for the mixed traffic safety evaluation of urban intersections. In the proposed model, the principle of the conservation of momentum is used. CHAM is a model used for assessing safety levels from the aspects of severe conflict numbers and conflict hazardous levels (CHLs) when traffic conflicts among mixed-traffic modes occur. Factors such as the conflict type and conflict angle of different traffic modes, weight and velocity are considered and incorporated into the model through the integration of the accident collision theory and the head injury criterion (HIC) index for head hazard assessments. The calibration and validation of CHL models are also carried out using 341 intersection crash reports in Beijing from 2006 to 2008. The results show that the established CHL models have good validity. [ABSTRACT FROM AUTHOR]