Optimizing Tied - Arch Bridges for Sustainability: A Study on Arch Size and Shape Modification

1 Introduction In a continuously evolving world, the field of civil engineering plays an increasingly fundamental role in a nation’s development. The need to create sustainable and resilient infrastructure, capable of minimizing environmental degradation and pre- serving natural resources for future generations, has become an absolute priority. In fact, Long et al. [1] affirm that the impact of global emissions and climate change is significantly influenced by urban centers worldwide, encompassing only 2 % of the Earth’s surface yet contributing to nearly 80 % of carbon emissions from human activities. The urban setting directly shapes our living standards, social welfare, and health. Therefore, the attributes and excellence of our infrastructures play a pivotal role in favoring urban sustainability and the overall health of our surroundings, considering that they constitutes at least 50 % of our national wealth [1]. In this context, parametric designs and optimization algorithms emerge as essential tools for guiding the decision-making process in civil engineering, enabling the planning of efficient and environmentally responsible solutions. Hence, extensive research and practical applications of new materials, construction methods, and design techniques are necessary [2]. This thesis focuses on modern optimization algorithms and parametric designs to evaluate the environmental impact of tied-arch bridges (a common infrastructure type worldwide). The focus is directed towards the arch’s shape and geometries with the aim of reducing steel requirements, consequently lowering costs and carbon dioxide emissions. To achieve this objective, a real tied-arch bridge was analyzed to validate the algorithm. This first chapter serves as an introduction to the topic. The second chapter begins with an introduction to the fundamental concepts of the optimization process, guiding the reader to the subsequent discussion on structural optimization. It further delves into the properties of tied-arch bridges and influence lines. Finally, the chapter addresses the analyses conducted on them in accordance with the Eurocodes, followed by the definition of the Global Warming Potential (GWP) [3], [4]. In the third chapter, an extensive exploration of the algorithm is given. This includes an in-depth look at the modeling of the optimization problem, the process of sizing and modeling the arch, the development of a finite element model (FEM), and the management of constraints. This chapter is the most comprehensive, and great care and attention were given to its content. 1