FRP约束海水海砂混凝土研究

In the rapid developing coastal regions of China, the huge demand of sand in the construction industry has led to an acute shortage of river sand, and an abuse of sea sand resulting in many quality problems. Against this background, this project proposes an innovative FRP confined seawater seasand concrete composite structure with internal FRP reinforcement; the concrete will be produced using seasand and seawater instead of river-sand and fresh water (referred to as “sea concrete” hereafter). The use of FRP reinforcement bars instead of steel reinforcements can avoid the major steel corrosion problem in steel reinforced concrete structures using sea sand. This project will first investigate the fundamental behavior of FRP confined sea concrete based on micro- and macro-scale finite element (FE) modelling and experimental studies to develop a tool to predict the distribution of chloride and sulfate ions and their relationships to the mechanical behavior. An advanced 3D FE model will further be developed to model the coupling effects of the distribution of ions and mechanical behavior. After validation with test data, the 3D model will be used to conduct extensive parametric studies to investigate the effects of a number of important factors and develop a stress-strain constitutive model of FRP confined sea concrete. This will form the basis for a comprehensive FE analysis of FRP confined sea concrete under axial and eccentric compression using a fiber model. These together with the results of a comprehensive test programme will be used to develop a design guideline for the FRP confined sea concrete members with and without internal FRP reinforcement. Lastly, a series of experimental studies will be carried to explore the effects of environmental exposure on the FRP confined sea concrete, based on which related design guideline will be developed. The success of this project can aid the rapid development of remote islands and coastal regions with significant economic benefits and environmental merits of preservation of precious natural resources.

我国沿海经济发达地区因基建需要近年相继出现河砂短缺和滥用海砂的现象。针对海砂所携带氯离子会造成钢筋锈蚀，本项目将研究FRP筋替代钢筋的FRP约束FRP筋海水海砂混凝土的基本性能。首先，结合细观与宏观有限元分析与试验测试，确定离子（主要是氯离子与硫酸根离子）在混凝土中的分布规律及其对力学性能的影响；进而建立能考虑离子分布与混凝土受力性能耦合作用的三维有限元模型，经试验数据验证与改进后，用于进行广泛的参数分析，发展FRP约束海水海砂混凝土的应力-应变关系模型。利用上述模型，建立基于纤维模型的FRP约束FRP筋海水海砂混凝土构件有限元模型并进行参数分析，建立FRP约束FRP筋海水海砂混凝土的设计理论。最后，通过试验研究澄清不同暴露环境的影响，发展考虑环境影响的FRP约束FRP筋海水海砂混凝土构件设计方法。本项目相关研究成果将极大促进我国海岛及沿海地区建设及经济发展，对资源及环境保护具有重要意义。

我国沿海经济发达地区因基建需要近年相继出现河砂短缺和滥用海砂的现象。针对海砂所携带氯离子会造成钢筋锈蚀，本项目研究FRP筋替代钢筋的FRP约束FRP筋海水海砂混凝土的基本性能。首先，采用模拟海水浸泡河砂得到了模拟海砂，并研究了模拟海砂和天然海砂的物理特性、离子含量和微观结构，并研究了海砂对混凝土工作性能的影响规律；采用具有不同离子组份及含量的模拟海水和模拟海砂制备混凝土，研究了不同离子种类及浓度对未约束混凝土和FRP约束混凝土力学特性的影响规律；采用天然海水、天然海砂制备混凝土，研究了不同龄期的约束和未约束海砂混凝土、海水混凝土及海水海砂混凝土的力学特性，并验证了现有FRP约束混凝土应力应变关系模型的适用性；研究了CFRP约束海水海砂混凝土柱的尺寸效应及养护龄期的影响；最后，研究了FRP约束FRP筋海水海砂混凝土的力学特性，初步并验证了该构件的有效性。. 通过本项目的实施，积累了大量的海水、海砂混凝土相关试验数据，为后续研究和应用奠定了重要基础。本项目的实施对促进我国海岛及沿海地区建设及经济发展，对资源及环境保护具有重要意义。