Simulation of Interactive Cyclic Local-Global Buckling in Steel Members Using Nonlocal Hybrid Element

计算机模拟对于预测建筑物和其他基础设施在地震或飓风等极端情况下的表现至关重要。在这种情况下，钢结构经常由于其部件(梁和柱)的扭转和屈曲而倒塌。这种类型的失效很难在计算机模型中模拟，因为目前的方法不能有效地表示扭转和屈曲的物理机制或它们之间的相互作用。该奖项支持基础研究，以创建一种以新颖的方式表示这些过程的物理过程的方法，从而能够更准确地模拟极端载荷下的结构失效。这项研究的发现和软件技术将增强建筑和其他基础设施的弹性，使国家的社会和经济受益。代表性不足的群体的参与、对具有新知识的学生的教育以及向实践者转让技术将产生更广泛的影响。在地震发生的循环荷载作用下，由于扭转和屈曲的相互作用，钢结构构件经常在极端荷载下失效。这一过程会导致强度损失，最终导致结构倒塌。目前用于模拟这一过程的方法不能直接模拟翘曲、扭曲和屈曲的物理现象，因此在预测失效方面受到严重影响。这项研究是一种新的科学公式，其中以一种新颖的方式表示构件的翘曲和扭转。该公式还允许通过“非局部”方法结合屈曲，从而使结果不是网格敏感的(即它们是客观的)。科学公式将在一个在结构工程师和研究人员中很受欢迎的开源数值平台中实施。这一方法(包括其实施)将通过大量可用的实验数据集和有限元模拟得到严格的信息和验证，并广泛传播给目标受众和用户群体。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Computer simulations are essential for predicting how buildings and other infrastructure will perform under extreme situations such as earthquakes or hurricanes. Under such conditions, steel structures often collapse due to twisting and buckling of its parts (beams and columns). This type of failure is challenging to simulate in computer models, because current methods cannot represent the physical mechanisms of twisting and buckling or their interactions in an effective manner. This award supports fundamental research to create a method that represents the physics of these processes in a novel way, enabling more accurate simulation of structural failure under extreme loads. The findings and software technology from this research will enhance the resilience of buildings and other infrastructure, benefiting the nation's society and economy. The involvement of underrepresented groups, education of students with new knowledge, and technology transfer to practitioners will result in broader impacts. Steel members often fail under extreme loads due to interactions between twisting and buckling under cyclic loading that occurs in earthquakes. This process leads to loss in strength, ultimately leading to structural collapse. Currently used methods for modeling this process do not directly simulate the physical phenomena of warping, twisting and buckling, and are therefore severely compromised in terms of their accuracy in predicting failure. This research is a new scientific formulation in which the warping and twisting of members is represented in a novel manner. This formulation also allows for the incorporation of buckling through a 'nonlocal' approach such that results are not mesh-sensitive (meaning that they are objective). The scientific formulation will be implemented in an open-source numerical platform that is popular among structural engineers and researchers. This approach (including its implementation) will be informed and validated rigorously by extensive available experimental datasets and finite element simulation, and broadly disseminated to target audiences and user groups.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.