【作者】 刘加湾；

【导师】 孙炳楠； 杨骊先；

【作者基本信息】 浙江大学 ， 结构工程， 2003， 硕士

【摘要】 既有混凝土桥梁结构的可靠性评估，是目前我国工程界急待解决的问题。既有混凝土桥梁结构的特点是抗力随时间不断衰减，但目前大多数的可靠度研究都没有涉及到抗力衰减。本文在抗力衰减模型及桥梁荷载模型的基础上，通过建立耐久性极限状态方程，分析计算桥梁可靠度随时间的变化情况。 本文首先考虑混凝土碳化、钢筋锈蚀、材料强度等单因素对桥梁结构抗力衰减的影响，然后在此基础上建立多因素综合作用下的结构抗力衰减模型。其中的重点是钢筋锈蚀对抗力衰减的影响，将钢筋锈蚀分为全面锈蚀及局部锈蚀两种情况。 荷载是桥梁结构上的主要作用之一，包括恒荷载及车辆荷载，它们均可以看成是随机变量。本文在国内外各种调查资料的基础上，分别引入恒荷载模型及车辆荷载模型，其中恒荷载呈正态分布：车辆荷载则为非正态分布，并将其分为一般运行状态及密集运行状态两种情况，分别建立服役期最大值分布函数。 在抗力衰减模型及桥梁荷载模型的基础上，将可靠度理论引入桥梁结构的评定中，推导出了桥梁结构耐久性极限状态方程，并根据耐久性极限状态方程中抗力是时间的函数，以及车辆荷载为非正态分布的特点，应用当量正态法(JC法)编制相应的程序计算桥梁构件的时变可靠度指标。通过一个具体工程实例，分别计算其在一般运行状态及密集运行状态时考虑全面锈蚀及局部锈蚀情况下的可靠度指标，并且讨论了恒载、车辆荷载、钢筋锈蚀速度、钢筋直径等参数对桥梁可靠度的影响。更多还原

【Abstract】 Reliability assessment of existing RC bridge is an urgent role to be reserved in our country. The structural characteristic of RC bridge is that the resisting force is deteriorating in life service of bridge,but most of reliability researches don’t consider the attenuation of resisting force until recent. In this paper,based on resisting force model and load model,the limit state equations of RC bridge are established,thus the time-dependent relationship of RC bridge reliability is analyzed.Firstly,each single factor(concrete carbonation,steel bar corrosion materials strength) related the resisting forces of RC bridges is considered in this paper. Then a resisting force model for multiple factors is created based on two types of steel bar corrosion:general and localized corrosion models.Load is a main factor to influence bridge. The main loads of RC bridge are deal load vehicle load which are random variables. Based on survey data from some researches,dead load model and vehicle load model are presented in this paper. It is quite evidence that dead load model is Gaussian distribution,and vehicle load is non-gaussian distribution,which operates general traffic and rush hour traffic states. At last distribution functions of load modes in life service are presented.Based on the resisting force model and load model,the limit state equations of RC bridge are formulated. According to the resisting force is time-dependent and vehicle load is the non-gaussian distribution,JC method is applied to calculate the time-dependent reliability index of RC bridge. Finally an engineering example is analyzed. Reliability index is determined considering two types of corrosion models and two types of vehicle models. The influences of some parameters,such as dead load live load,corrosion speed,diameter of steel bar,are analyzed.更多还原