Papers by Keyword: Time-Variant Reliability

Abstract: Global climate change, including climate deterioration and extreme weather events, has serious impacts on reliability of bridge superstructure. Global warming and increasing velocity of wind associate with the increase of CO2 level play a dominate role in reliability degradation. For the highway bridge in offshore environment, a main factor of reinforcing steel corrosion is the invasion of chloride ion, which can cause durable damage of the structures. Moreover, temperature rises will increase corrosion rates. In addition, changes in maximum wind speeds may increase expected wind loads on bridge structures. This paper develops a reliability analysis model to assess the reliability degradation of the highway bridge superstructure under (i) base case, (ii) temperature rising case, (iii) wind speed changing case, and (iv) combination of case (ii) and case (iii). The process is illustrated by studying the reliability of a offshore highway bridge using simplified models of the structure. It is demonstrated that the reliability degradation will be greatly accelerated taking account of climate change. The life expectancy of the structure will be 10 years and 70 years lower than base case if the target reliability is 4.5.

Abstract: A novel time-variant reliability model is developed after studying the traditional dynamic performance of mechanism. The expression of reliability is given based on stochastic process. A two-dimensional description of the error generating process is established by studying mechanism output kinematic accuracy. The reliability of mechanism output kinematic accuracy can be obtained according to this description. The model proposed can be used to calculate the reliability of mechanism directly, if the distribution of mechanism output kinematic accuracy is known.

Abstract: Based on the characteristics of loading condition of ship structure in service and the degeneration of the strength under fatigue and corrosion, the random time-variant model of ship hull section modulus was set up using the theory of random process. Then the time-variant reliability was analyzed with the method of up-crossing analysis and parallel system reliability. This method could not only present successive decrease of reliability of the ship structure under fatigue and corrosion, but also avoid the complicated numerical integration. It could be seen that this method was easy to achieve. Furthermore, the time-variant reliability was compared with the annual instantaneous reliability through an example, which indicated that this method was more precise, and could provide some references to the decision-making of the reliability, maintenance and safeguard.