Computational Design Methods for the Optimization of the Density Distribution in Graded Concrete Components under static and dynamic loading

本研究旨在开发一种数值设计工具，用于确定静力和动力作用下功能梯度结构混凝土构件内的最佳密度分布。该工具应用于设计用于动态加载的功能分级框架组件，然后在ILEK生产并在伯克利进行测试。功能梯度结构元件的特征是其特性随位置的变化而不断变化。混凝土的密度级配(即组件内孔隙率的连续变化)用于准确地调整材料的性能以适应其所受的作用。高冲击区由高性能混凝土组成，而低冲击区由多孔混凝土组成。这种方法可以节省高达60%的材料质量，例如在承受弯曲的地板结构中。初步测试表明，这种新的轻质施工方法具有很高的吸能能力，只有在发展了数值设计方法后，才有可能确定连续的、三维的性能级配模式。由于简化的几何形状、线弹性材料假设以及优化构件刚度的限制，初步研究中实施的优化步骤受到限制。方法仅限于商业上可用的优化工具(ABAQUS Atom)中提供的算法、设计变量和目标函数。不可能改变或调整这些参数。在申请研究资助的范围内开发的设计工具还应能够在考虑静态限制的同时实现导热系数的优化，并使设计受动态作用的密度布局成为可能。然后应免费提供设计工具，为传播新办法作出贡献。加州大学伯克利分校开发了一些优化算法和模拟方法，如描述混凝土材料非线性行为的混凝土损伤塑性模型。自1983年以来，菲利波教授一直致力于描述承受静力和动力作用的混凝土结构。因此，负责相关活动的科学家团队和东道国大学现有的基础设施为成功完成设想的研究项目提供了完美的环境。一旦完成，该项目将提供设计方法，以确定承受静态、温度和动态作用的结构混凝土组件的三维属性等级。除了ILEK目前正在开发的制造流程自动化之外，该设计工具还缺少可靠地生产具有自由、三维密度梯度的结构混凝土部件的环节。

This research aims to develop a numerical design tool for determining the optimal density distribution within functionally graded structural concrete components subject to static and dynamic actions. This tool should be used to design functionally graded frame components for dynamic loading, which are then to be produced at ILEK and tested in Berkeley. Functionally graded structural components are characterized by location-dependent, continuous changes in their properties. Density gradation of concretes (i.e. a continuous change in the porosity within the component) serves to accurately adjust the properties of the material to the actions it is subjected to. High-impact zones are made from high-performance concrete whereas low-impact zones consist of porous concrete. This approach makes it possible to save up to 60% of the mass of the material, such as in floor structures subject to bending. Initial tests showed that this new lightweight construction method was associated with a high energy absorption capacity.Only after developing numerical design methods will it become possible to determine continuous, three-dimensional property gradation patterns. The optimization steps implemented in the preliminary research were limited on account of the simplified geometry, the linearly elastic material assumption, and the restriction to optimizing component rigidity. Methods were limited to the algorithms, design variables, and target functions provided in the commercially available optimization tool (Abaqus Atom). No alteration or adjustment of these parameters was possible. The design tool to be developed within the scope of the applied-for research grant should also enable thermal conductivity optimization whilst considering static restrictions and make it possible to design a density layout subject to dynamic actions. The design tool should then be made available free of charge to make a contribution to disseminating the new approach. Some of the optimization algorithms and simulation methods, such as the Concrete Damaged Plasticity Model to describe the non-linear material behavior of concrete, were developed at the University of California at Berkeley. Prof. Filippou has been conducting research on describing concrete structures subject to static and dynamic actions since 1983. The team of scientists tasked with the related activities and the existing infrastructure at the host university thus provide the perfect setting to successfully complete the envisaged research project. Once completed, this project will provide design methods to determine three-dimensional property gradations for structural concrete components subject to static, thermal, and dynamic actions. Besides the automation of manufacturing processes currently under development at ILEK, this design tool is the missing link to reliably produce structural concrete components with free, three-dimensional density gradation.