Service life evaluation system for durability of structures at the time of planning and design

规划设计时结构耐久性的使用寿命评估系统

基本信息

批准号：
12355019
负责人：
OKAMURA Hajime
金额：
$ 23.24万
依托单位：
Kochi University of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

项目摘要

A framework was achieved for the durability in the service life of concrete structures, which is supposed to be carried out at the time of the design and planning before its construction. An evaluation method for initial properties to be achieved in RC structures was developed, in which the factors affecting the properties are construction method, structural details, and material properties and it made possible to evaluate the degree of the influence from each factor quantitatively and to evaluate initial properties of concrete simply. An evaluation method for time-dependent material and structural properties was developed by expanding thermo-hygro analysis system so that the interaction among hydration, micro-pore stricture, and moisture equilibrium can be treated. The concentrations of chloride ion, carbon dioxide, and oxygen were attached to the governing equations in the model and then as much as 100 parameters became included in the element model. It made possible to estimate the time-dependent deterioration of material and structural performance of structure.In the other hand, the model for each factors in durability of concrete structures were also modified as follows : structural behavior of RC member with corroded reinforcing bar, moisture transport in concrete with cracks, hydration rate of concrete with low water to cement ratio, interaction between autogenous- and drying shrinkages, effect of limestone powder on chloride diffusivity in concrete. In addition, fresh properties affecting the long term durability were also investigated. Influence of surface moisture content on the flowability of fresh concrete was investigated. The factors affecting the degree of sinking of coarse aggregate particles into mortar were examined, which affects the uniformity of concrete s composition.

为混凝土结构的使用寿命建立了一个框架，该框架应该在施工前的设计和规划时进行。建立了RC结构初始性能评价方法，其中影响性能的因素有施工方法、结构细节和材料性能，可以定量评价各因素的影响程度，并评价其性能。简单地介绍混凝土的初始特性。通过扩展热湿分析系统，开发了一种随时间变化的材料和结构性能的评估方法，从而可以处理水化、微孔结构和水分平衡之间的相互作用。将氯离子、二氧化碳和氧气的浓度附加到模型中的控制方程中，然后将多达 100 个参数纳入元素模型中。它使得估计材料和结构性能随时间的变化成为可能。另一方面，混凝土结构耐久性每个因素的模型也进行了如下修改：钢筋锈蚀的钢筋混凝土构件的结构行为、湿度裂缝混凝土中的传输、低水灰比混凝土的水化速率、自生收缩和干燥收缩之间的相互作用、石灰石粉对混凝土中氯化物扩散性的影响。此外，还研究了影响长期耐久性的新鲜特性。研究了表面含水率对新拌混凝土流动性的影响。研究了影响粗骨料颗粒沉入砂浆程度的因素，从而影响混凝土成分的均匀性。