Functionally Graded Concrete for The Civil Infrastructure - A Multifunctional Material System Approach

该项目开发了用于民用基础设施的新型多功能和功能梯度混凝土材料（FGCM）。FGCM由一个结构层内的多个子区域组成，其中不同的混凝土成分遵循预定义的组成函数，例如具有不同厚度韧性的功能梯度纤维增强混凝土板。将进行多尺度测试（包括小尺度试件断裂测试和混凝土板的大尺度测试）、建模和教育计划，以实现项目目标。集成建模将完成不同的本构描述的散装（与特殊梯度有限元）和？分居？（开裂）材料的微观结构，以及一种定制的内聚区模型方法，能够捕捉材料降解和中尺度材料梯度效应。一个虚拟的内部债券（VIB）模型也将制定一个连续的应变局部化的方法，采用一个新的对键电位的概念。一个全面的教育计划显然是必不可少的，因为这个项目的成功，需要教学的学生（内接触）和实践工程师（外接触），以实现多尺度FGCM测试和断裂建模程序。综合研究和教育计划预计将对以下领域产生广泛的影响：基础设施材料研究，通过在UIUC开发综合设计课程的土木工程学生教育？基础设施用功能梯度混凝土材料的工程设计通过开展技术转让活动（例如短期课程）与执业工程师互动，为本科生和研究生研究助理提供研究经验和指导，为代表性不足的学生提供暑期指导和研究经验。

This project develops novel multifunctional and functionally graded concrete materials (FGCMs) for the civil infrastructure. FGCMs consist of multiple sub-regions within a structural layer with varying concrete constituents following a predefined compositional function, e.g. functionally graded fiber-reinforced concrete slab with varying through-thickness toughness. A multi-scale testing (including small-scale specimen fracture tests and large-scale tests of concrete slabs), modeling, and education plan will be undertaken to achieve the project goals. The integrated modeling will be accomplished by distinct constitutive descriptions for the bulk (with special graded finite elements) and the ?separation? (cracked) materials through and a tailored cohesive zone model approach able to capture material degradation and material gradient effects at the mesoscale. A virtual internal bond (VIB) model will also be formulated using a continuum approach for strain localization employing a new pair-bond potential concept. A comprehensive educational plan is clearly essential to the success of this project since teaching of students (in-reach) and practicing engineers (out-reach) are needed to implement the multi-scale FGCM testing and fracture modeling program. The integrated research and education plan is expected to have a broad impact on the following areas: infrastructure materials research, civil engineering student education through development of an integrated design course at UIUC on ?Engineering Functionally Graded Concrete Materials for the Infrastructure,? interaction with practicing engineers through development of technology transfer activities (e.g. short courses), research experience and mentoring for undergraduate students and graduate research assistants, and summer mentoring and research experience for underrepresented students.