Optimum strut-and-tie model for a cantilever curved wall

摘要

Topology optimization can be used as a tool for the development of optimized reinforcement configurations within concrete members. Topology optimization is the process of optimizing the distribution of material within a design domain, so as to increase the efficiency with which the material used. This project will focus on the optimized design of a curved cantilever wall, made of concrete and reinforced through the traditional method of placing reinforcing steel.Sigmund (2001) published the paper, A 99 line topology optimization code written in Matlab, detailing the process of modelling and optimizing a domain to determine the load transfer path within the member. This code employs a finite element analysis operation, this being dependant on the use of square elements.The current code prepared by Andreassen et al only consider domains constructed of square, uniform finite elements, thus having limited capabilities in modelling structures. The overall aim of this project is to modify and make additions to the code to extend its capabilities in modelling domains constructed of non-square quadrilateral elements with non-uniform geometry and volume.A curved domain was arbitrarily formed and loaded with a single point load. One boundary along its least dimension was fixed. A finite element mesh was created for this domain and was used as the input for the modified optimization code. This code successfully optimized the topology of the given domain, producing results that showed the possibility of developing an optimized strut-and-tie model.Whilst the optimization program functioned, the mesh used to define the domain was too coarse, proving the results unusable for the development of an objective, optimized topology. The formation of a closed form truss structure, required for a strut-and-tie model, was seen to be forming, but a producing a strut-and-tie model from such would have been highly subjective and inefficient. A refinement of the finite element mesh, allowing for a lower minimum member size will allow for the development of an objective topology optimization. In doing so, an efficiently designed strut-and-tie model can be produced.