In the traditional bridge seismic fragility analysis, the criterion for judging the structural damage state is clear. That is to say, when the damage index exceeds a specific value, the structure is judged to enter the new damage state. However, the actual condition is that the boundary of structural damage is not clear but fuzzy. Taking a three-span V-shaped continuous girder bridge as an example, the damage process of the structure is described by fuzzy mathematics. Considering the uncertainties of ground motion and structure itself, a seismic fragility analysis method is established, which can consider the randomness of bridge itself, seismic load, and structural failure fuzziness simultaneously. Finally, the improved product of conditional marginal (I-PCM) method for fragility analysis of bridge system is further optimized and improved. The new improved method is used to form the seismic fragility curves of bridge structure system. The results show that it is possible to underestimate the potential seismic fragility of bridge components and system without considering the structural fuzzy failure criteria; the fragility curves formed by different membership functions are obviously different; the new system fragility analysis method can significantly improve the analysis accuracy.
As the key node of highway transportation line, bridges are easy to be damaged under earthquake. When bridge earthquake damage occurs, traffic will often be interrupted, resulting in traffic network paralysis in disaster areas, seriously affecting the development of post-earthquake rescue work, thereby further aggravating the loss of personnel and property. In this paper, a performance-based method for evaluating the post-earthquake capacity of bridge system is proposed, and the post-earthquake operational status of the bridge system is evaluated. The results show that the performance-based assessment of bridge capacity after earthquake is of great value in evaluating the operation status of bridge system and making operational management decisions. Based on the fragility analysis of bridge components, the I-PCM method can be used to quickly establish the fragility curve of bridge system; meanwhile, combined with the performance-based evaluation model of seismic damage bridge capacity, the rapid evaluation of bridge capacity after earthquake is completed.
Abstract. In this paper, the reliability theory of engineering structure based on a city landscape bridge (multi span prestressed concrete V-shaped pier continuous beam bridge) as engineering background, key section of main girder and V-shaped pier of continuous girder bridge of prestressed concrete V-shaped pier by using the first two order moment method to evaluate the bridge girder and the shape of V-pier bridge reliability index, reflect design intent; and the influence of various factors on the reliability index of sensitivity analysis in the design reference period of resistance of this kind of bridge reliability greatly. The influence of the variation of the dead load on the reliability of the main beam is negligible, but it has great influence on the reliability of the V-shaped pier. The effect of live load effect on the reliability of the main beam is very significant, and the effect on the reliability of V-shaped pier is small. Therefore, this study has certain engineering value for the design, operation, maintenance and monitoring of the multi span prestressed concrete V-shaped pier continuous beam.
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