コンクリートの凍害および凍害－疲労複合劣化シミュレーション

本研究主要针对混凝土结构的冻害问题，以及外界荷载的组合效应，开发一套细观分析系统。到目前为止，本课题研究的主要目的还没有建立全面的物理力学模型和数值计算方法，较好地完成了原研究计划。两篇关于纯粹霜冻损害的物理模型和数值模拟的期刊论文；一篇关于霜冻作用和静态荷载组合的建模和模拟的论文(正在审阅中)；另一篇关于霜冻作用和疲劳荷载组合效应的论文(正在撰写中)。还发表了几篇会议论文。具体研究成果如下：(1)建立了混凝土材料内部在温度和潮湿条件下产生的孔压的理论物理模型。(2)在刚体弹簧模型(RSBM)的基础上，建立了细观模拟模型，利用建立的孔压模型可以模拟材料的变形。(3)基于多相复合理论，建立了不同冰量、液态水和空气掺量下混凝土的有效弹性模量和强度的表达式，并用径向基函数法对其进行了模拟。(4)对疲劳荷载作用下RBSM的本构模型进行了修正，并考虑了内压引起的冻害。模拟了FTC未损伤混凝土和损伤混凝土的S-N曲线。

This research is mainly to develop a mesoscale analyzing system for the frost damage problems of concrete structures, together with the combining effects by external loads. Till now, the comprehensive physical and mechanical model, as well as the numerical method are still absent, which are the main purposes of this research project.The original research plan has been accomplished well. Two journal papers for the physical model and numerical simulation of pure frost damage; one paper (under review) for the modeling and simulation of combined frost action and static loads; another one (under writing) for the combined frost effect with fatigue loading. Several conference papers are also published. The details of outcomes are as follows:(1) The theoretical physical model has been developed to calculate the pore pressures generated inside the concrete material under variation of temperatures and moist conditions. (2) The mesoscale simulation model has been developed based on Rigid Body Spring Model (RSBM), and using the pore pressure model developed above, the material deformation can be simulated. (3) Based on the multi-phase composite theory, the expression of effective elastic modulus and strength of concrete with different amount of ice, liquid water and air is developed and simulated by RBSM. (4) The constitutive model for RBSM under fatigue loading is modified, and combining with frost damage caused by internal pressures. The S-N curve for FTC undamaged and damaged concrete are simulated.