【作者】 刘重霄；

【导师】 向阳开；

【作者基本信息】 重庆交通大学 ， 桥梁与隧道工程， 2008， 硕士

【摘要】 由于混凝土碳化、钢筋锈蚀、车辆荷载的不断重复及增加以及养护维修欠缺,桥梁结构在服役一段时间后将产生各种结构损伤,导致结构承载力降低,运营状况不能满足规定要求。所以合理评估既有桥梁承载能力是保证线路安全的一项重要工作。本文针对既有钢筋混凝土桥梁,充分考虑钢筋锈蚀、混凝土劣化、粘结强度衰减等因素对结构承载力的影响,研究各种损伤与承载力的关系,将各种损伤演化率引进到结构抗弯、抗剪等实效模式的抗力计算式中,构造以时间为因变量的抗力表达式,对桥梁承载能力进行了分析和评估;并通过建立承载能力极限状态方程,研究了桥梁可靠度随时间的变化情况,将动态可靠度与损伤评估结合起来,从而实现对既有钢筋混凝土桥梁的承载能力及寿命的评估和预测。本文以“混凝土碳化-钢筋锈蚀与混凝土劣化-锈蚀钢筋混凝土构件的力学性能退化-锈蚀桥梁结构承载力评估”为主线,论文对以下几方面做了系统研究:(1)对混凝土碳化深度随时间变化规律做了研究,为进一步研究混凝土中钢筋锈蚀提供了基础;(2)对影响钢筋混凝土梁承载力的各种因素进行了分析;(3)通过分析引起锈蚀钢筋混凝土结构性能退化的影响因素,探讨了对锈蚀钢筋混凝土基本构件进行非线性有限元模拟的分析方法,并用有限元程序ANSYS,对不同锈蚀率下锈蚀钢筋混凝土梁的力学性能退化规律进行了分析研究;(4)根据理论成果,研究了锈蚀钢筋混凝土梁承载能力的合理计算方法,并代入时间因素得到了以时间为因变量的既有钢筋混凝土结构抗力表达式;(5)在桥梁结构承载能力衰减模型及桥梁荷载模型的基础上,推导出了损伤状态下桥梁结构承载力极限状态方程。将可靠度理论引入桥梁结构的评定中,对一实际的预应力钢筋混凝土简支梁桥进行了承载能力及预期寿命的评估和预测,并编制了相应的计算程序。最后,对进一步工作的方向进行了简要的讨论。更多还原

【Abstract】 Due to concrete carbonation, steel-bar corrosion, vehicle load increasing and deficiency of maintenance, some bridges expose various structural deterioration ,and it maybe cause the loss of bearing capacity and the decrement in performances of structures resulting in unsafe factors compared with the requirements of the design code. Therefore, the reasonable evaluation on the bearing capacity of existing bridges is an urgent issue in order to insuring the safety of the structures.In this paper,base on considering the factors as steel-bar corrosion、concrete deterioration,bond strength decay which influence the structure bearing capacity, studying the relation between damage and bearing capacity. introducing each damage evolvement rate into the structure resistance expression of flexural capacity and shear capacity , constructing the resistance expression base on variable ingredient of time and accordingly,by construct limit state equation,study the reliability change with time,combine the dynamic reliability with damage assess, the evaluation and forecast of existing bridge capacity and life is come ture.In accordance with the study process of“concrete carbonation-mechanical properties of corrosive steel-bars and concrte degenerate—deterioration of mechanical properties of corrosive reinforced concrete members—durability estimation of corrosive bridge structure bearing capacity”,systematical study of corrosive concrete structures, is summarized by the author as follows:(1) The rule of carbonation depth changed by time is discussed, it make the basis of the next studying of the corrosive steel-bar (2) various of factors which influence the capacity of bridge is analyse.(3)by study the factor which lead the degenerate of capacity of bridge, probe and discuss the method of Nonlinear finite element to simulate the corrded reinforced beam,and with the help of ANSYS, the degenerate rule of mechanical properties of different corrosive ratio is study and analyses (4) on the basis of academic, the reasonable method of bearing capacity is studied, educing the expression of resistance by introduce the factor of time (5) On the basis of degenerate model of bridge capacity,the limit state expression in damage state is educed ,introduce reliability theory into the evaluation and forecast of bridge.the capacity and life of a real Pre-stressed concrete bridge is evaluated and forecasted ,and a program based on the example are coded respectively. And finally, the direction of further research is briefly discussed.更多还原