Integrated steel design through automation

Structural engineers lack methods to accurately assess the construction costs of their design choices, particularly in early design phases. Conventional practice for steel structures is to estimate costs based on steel weight, but the cost of a steel structure is a function of many factors independent of the weight of steel. Consequently, engineers lack the basis for design decisions that result in the most economical structures for their clients. Steel fabricators have the expertise and cost data to improve designs, but organizational or contractual barriers often prevent their collaboration when engineers make the cost-critical design decisions. I propose to overcome these barriers with a systems-level design framework that automates the design process from sizing to connection detailing and analytical cost estimation. The automation of the design process and the integration with fabricator cost data allow for integrated design and design exploration to a degree that is impractical today due to the cost and time requirements using existing methods. Detailed-cost estimates are highly dependent on the connections between steel members, which define most of the labor costs. Along with the type of connection, the sizes of the members coming together are a major factor in the cost of a connection. Determining the cost-optimal sizes for a structural frame is beyond the capability, or too computationally expensive, of available optimization methods. The design space, or number of possible size combinations, is typically vast for even small structures. In response, I developed a new method to quickly optimize the member sizes based on minimum cost and all applicable global and local constraints. The method is a novel implementation of the virtual-work method. It utilizes the Pareto set of designs with the global constraint function regarded as a second objective function. This method enables an effective search for optimal or near-optimal sizes that is not practical using metaheuristic methods, and not within the capability of existing virtual-work methods. With known optimal sizes, designers can then use traditional search techniques to efficiently evaluate alternative structural layouts or systems, as removing the size variables reduces the design space by orders of magnitude. The proposed optimization method compares favorably to existing methods for the example problems provided. Most significantly, it achieves better results within just a dozen iterations, than the competing methods do over 10,000s of analyzed designs. I tie this new method of integrated steel design to the broader subject of integrated design and project delivery using case studies. They show how automated systems and electronic data interchanges can overcome the traditional barriers to applying integrated design practices to the construction industry. The tools and knowledge are available, and I hope that this research will contribute to the ever-expanding case to drive broader acceptance of innovative techniques within the industry. With continued innovation, we may finally experience a change point in the industry, where technology drastically drives down costs and increases quality and customer satisfaction. This has been predicted since the beginning of the last century but has yet to materialize at scale

Advisor: Fischer Martin
Lepech Michael 
Miranda Eduardo (Miranda Mijares)