钢筋砼构件氯离子侵蚀下钢筋初始锈蚀时间的计算方法-结构工程专业论文.docxVIP

北京工业大学工学硕士学位论文关键词：氯离子 北京工业大学工学硕士学位论文 关键词：氯离子 耐久性动态可靠度 钢筋初始锈蚀时间 圆形截面 矩形截面 ．U． AB AB STRACT It has been proVed that the resistance of the member of reinf’orced concrete sCmcture is continuously changing with its service—time。 The result of this fact is that the reliability of the structure is changing with the service—time，that is，the reliabmty is dynamic。Recently，a lot of research regarding the durability and dynamic has been made jn tbe natjon and abroad。 Because commonly出e degenefatjon of the fesistance begins with the corrosion of the steel in the concrete，i“s very imponant for durabmty research to cou眦the beginning corrosion time ofthe steel in t}幢concrete a There is a lot of chloride in ocean enviroment which is a main reason of the steel corrosion， so we must predict thickness of chlorine ion in order to count the beginning corrosion time of the steel under sea environment。But current calculating formuIa is unsuitable not only to counting the beginning corrosion time of the steel， but also to practically apllying because its hypotheses is much too ideally and the innuence of section shape。 So ， based on preVious research achieVement and the knowledge regarding molecular movemem and calculus a11d numerical Value analysis，practical calculating method is set up in this p印er： 1．Traditional model is transfb蛐ed and its ajlti—model is set up，which makes the calculation ofbegi衄ing corrosion time ofsteel Very easy； 2．Based on tlle first FICK dimlsion law，mathematical model oftwo，dimension difrusion of Cl～is set up and baSed on this，one—dimension dif如sion model ofCI—ofcircular secnon： 3． Di行erential arithmetic is utilized to set up the n哪erical value arithmetic of the diHhsion model of circul甜and rectangular section； at the same time，the stability ofthe numerical value arimmetic is analyzed； 4． Modi母ing coe街cient is used to modify the traditional model： 5． Mally factors rcgarding the modifying coemcients of circular and rectallgular section are analyzed： (1) It is theo