CAREER: Fracture Analyses in Concrete via Experimentation & Simulation (FRANCES): Examining Discrete Crack and Fracture Modeling of Concrete Under Blast and Impact Loading

本学院早期职业发展（CAREER）计划项目的研究目标是开发一个可重构本构多尺度模型，该模型能够模拟极端载荷下混凝土的动态断裂。 在设计关键防护结构时，混凝土在承受爆炸和冲击等动态载荷时的非线性和断裂行为是一个越来越重要的考虑因素。为了验证将要开发的模型，将使用从落塔冲击试验中收集的试验数据和从钢筋混凝土板上的激波管试验中获得的爆炸响应数据。 冲击和爆炸载荷试验将在位于密西西比维克斯堡的美国陆军工程兵工程研究与发展中心进行。该数值模型将能够模拟离散裂纹萌生，而无需对裂纹路径进行任何预先规定。该数值模型将在流行的商业有限元程序ABAQUS和LSDYNA中实现，并使用项目数据和其他可用的实验测试数据进行验证。本文将对一个七层钢筋混凝土结构在爆炸荷载作用下的行为进行模拟研究。该数值模型的改进也将用于PI目前对牙本质和骨中存在的矿物质和胶原纤维等纳米尺寸颗粒的力学行为的研究。为了更广泛地影响和传播结果，该项目将为设计师和教育工作者开发教育材料。联邦紧急事务管理局第451号出版物中给出的例子将得到扩充，以包括ASCE 7评注中规定的爆炸载荷情况。研究结果也将提供给代码编写机构，如ACI 318，将应变率效应纳入设计规定。除了研究生外，本科生也将通过NSF和大学项目（如EMBA）参与该项目。 与高中学生的外联活动将通过NSF资助的项目ARROWS进行。

The research objective of this Faculty Early Career Development (CAREER) Program project is to develop a fracture-constitutive multi-scale model which is able to simulate dynamic fracture in concrete subjected to extreme loadings. The non-linear and fracture behavior of concrete when subjected to dynamic loads such as blast and impact is an increasingly important consideration when designing critical protective structures. To validate the model to be developed, test data collected from a drop tower impact test and blast response data obtained from a shock tube test on reinforced concrete panels will be used. The impact and blast loading tests will be conducted at the US Army Corps of Engineers-Engineering Research and Development Center at Vicksburg, Mississippi. The numerical model will be able to simulate discrete crack initiation without any pre-specifications about the crack path. The numerical model will be implemented in the popular commercial finite element programs ABAQUS and LSDYNA and verified using the project data and other available experimental test data. The behavior of a seven story reinforced concrete structure subjected to blast loading will be simulated and studied. The enhancements to the numerical model will also be utilized in the PI's current study of the mechanical behavior of nano-sized particles such as minerals and collagen fibrils present in dentin and bone.For broader impact and dissemination of the results, the project will develop educational materials for designers and educators. Examples given in Federal Emergency Management Agency Publication 451 will be augmented to include the blast loading case, as specified in ASCE 7 commentary. The research results will also be made available to code writing bodies such as ACI 318 to incorporate the strain rate effects in design provisions. Besides the graduate students, the undergraduate students will also be involved in the project through NSF and the university programs such as SEARCH. Outreach activities with High School students will be incorporated through the NSF funded project ARROWS.