【作者】 严甜；

【导师】 李惠；

【作者基本信息】 哈尔滨工业大学 ， 防灾减灾工程及防护工程， 2010， 硕士

【摘要】 大型桥梁结构在服役期间由于受外界环境、荷载等因素的影响,性能不断退化。为了保障桥梁结构服役期间的安全与可靠,需对结构进行检测和维修。不恰当的维修决策将导致桥梁结构全寿命周期成本过高,或引起桥梁结构失效造成严重的经济损失,因此,开展桥梁结构的全寿命设计方法的研究具有重要的现实意义。本文基于马尔可夫决策过程(Markov Decision Processes,简记为MDP)对桥梁结构全寿命成本及桥梁结构的维修策略开展研究。本文主要内容如下:首先,针对隐式极限状态方程且非线性程度较高时,响应面法求解可靠指标的误差大,而采用Monte Carlo抽样包括重要抽样方法,虽然精度高但计算效率低,对于结构有限元分析进行抽样几乎不能实现的状况,本文提出采用Kriging插值技术建立极限状态超曲面的代理模型,在验算点处应用Monte Carlo重要抽样方法对代理模型抽样进而求得结构的失效概率。结果表明:方法在隐式极限状态方程且非线性程度较高时精度良好,同时较Monte Carlo抽样或重要抽样效率高。其次,建立了基于MDP的全寿命成本分析方法,采用值迭代法得到结构寿命周期最优维修策略。研究结构的自身转移矩阵、维修决策影响矩阵及状态综合转移矩阵的确定方法,并以此为基础建立桥梁结构性能退化的马尔可夫模型及桥梁结构全寿命最优维修决策模型。最后,以桥梁结构全寿命总成本最小为目标,以可靠指标为约束建立桥梁结构全寿命总成本评价模型;采用基于MDP的全寿命分析方法确定一般桥梁结构的最优初始抗力和全寿命周期内的最优维修策略,研究初始抗力、抗力衰减规律、折现率、失效费用对桥梁结构全寿命周期内可靠指标、总成本及维修决策的影响规律。更多还原

【Abstract】 Large bridges are deteriorating continuously during their service lives, because of external environment, load and other factors. Necessary maintenance and inspection should be taken on bridge structures for ensuring safety and reliability during service. However, irrelevancy maintenance policies may lead to high life-cycle cost or structural failure, cause enormous economic loss. Life-cycle design of bridge structure has great research significance. This dissertation focuses on investigation of life-cycle cost and maintenance policy of bridge structure by using a Markov Decision Processes-based (MDP) modeling approach. The main contents are as follows:Firstly, a new method based on Kringing technology and Monte Carlo important sampling was proposed for structural reliability analysis. Kriging technology can be used to alleviate the computational burden as well as response surface method (RSM). However, surrogate model constructed by Kriging technology is more accurate than that constructed by RSM, especially when the limit state function is strong nonlinear. Monte Carlo important sampling was used to obtain the failure probability of this surrogate model. The results show that the proposed method has excellent accuracy and is more efficient than the direct Monte Carlo sampling and important sampling.Then, a life cycle design method based on MDP was proposed and value iteration method was used to identify optimal maintenance policy. In order to build the Markov degradation model of bridge structures and determine the optimal maintence policy, the methods used to determine the self-transition matrix, decision-effect matrix and joint-transition matrix were researched.Finally, holding the objective of minimization of expected life-cycle cost, the economic model of bridge life-cycle design was developed to satisfy the reliability index. A MDP modeling approach was used to identify optimal structural initial resistance and their associated maintenance policies. The effects of initial resistance, resistance deterioration, discount rate and failure loss on bridge life-cycle costs, reliability index and maintenance policy were discussed.更多还原