A model of dynamic programming for repairing strategies of concrete structures during a projected service period is proposed, which takes into account the degradation in strength of components and the probability of a...A model of dynamic programming for repairing strategies of concrete structures during a projected service period is proposed, which takes into account the degradation in strength of components and the probability of accidental load. This model takes the safety grade of a structural system as the state variable of repairing strategies, and incorporates economic factors including expected repair cost, property loss due to structure failure, goods and material loss due to structure failure, loss of production interrupt due to structure failure, and inspection cost in decision making. It is found that the optimal repairing strategies are sensitive to the probability of accidental loads as well as the failure costs. The practicality of the model is demonstrated by an example.展开更多
To accurately assess the safety of freeway work zones, this paper investigates the safety of vehicle lane change maneuvers with improved cellular automata model. Taking the traffic conflict and standard deviation of o...To accurately assess the safety of freeway work zones, this paper investigates the safety of vehicle lane change maneuvers with improved cellular automata model. Taking the traffic conflict and standard deviation of operating speed as the evaluation indexes, the study evaluates the freeway work zone safety. With improved deceleration probability in car-following rules and the addition of lanechanging rules under critical state, the lane-changing behavior under critical state is defined as a conflict count. Through 72 schemes of simulation runs, the possible states of the traffic flow are carefully studied. The results show that under the condition of constant saturation traffic conflict count and vehicle speed standard deviation reach their maximums when the mixed rate of heave vehicles is 40%. Meanwhile, in the case of constant heavy vehicles mix, traffic conflict count and vehicle speed standard deviation reach maximum values when saturation rate is 0.75. Integrating all simulation results, it is known the traffic safety in freeway work zones is classified into four levels： safe, relatively safe, relatively dangerous, and dangerous.展开更多
基金Funded by the National Key Project on Basic Research and Applied Research (85-40).
文摘A model of dynamic programming for repairing strategies of concrete structures during a projected service period is proposed, which takes into account the degradation in strength of components and the probability of accidental load. This model takes the safety grade of a structural system as the state variable of repairing strategies, and incorporates economic factors including expected repair cost, property loss due to structure failure, goods and material loss due to structure failure, loss of production interrupt due to structure failure, and inspection cost in decision making. It is found that the optimal repairing strategies are sensitive to the probability of accidental loads as well as the failure costs. The practicality of the model is demonstrated by an example.
基金supported by National Natural Science Foundation of China(No.51208053)the Special Fund for Basic Scientific Research of Central Colleges,Chang'an University(No.00092014G1211011,2013G1211009)
文摘To accurately assess the safety of freeway work zones, this paper investigates the safety of vehicle lane change maneuvers with improved cellular automata model. Taking the traffic conflict and standard deviation of operating speed as the evaluation indexes, the study evaluates the freeway work zone safety. With improved deceleration probability in car-following rules and the addition of lanechanging rules under critical state, the lane-changing behavior under critical state is defined as a conflict count. Through 72 schemes of simulation runs, the possible states of the traffic flow are carefully studied. The results show that under the condition of constant saturation traffic conflict count and vehicle speed standard deviation reach their maximums when the mixed rate of heave vehicles is 40%. Meanwhile, in the case of constant heavy vehicles mix, traffic conflict count and vehicle speed standard deviation reach maximum values when saturation rate is 0.75. Integrating all simulation results, it is known the traffic safety in freeway work zones is classified into four levels： safe, relatively safe, relatively dangerous, and dangerous.
