# Optimization of Glulam Regular Double-Tapered Beams for Agroforestry Constructions
## 1 Introduction  
Until the Industrial Revolution, timber was one of the main materials used in construction. However, with the popularization of new materials such as steel and reinforced concrete, timber's use began to decline due to the limited size of the timber elements, which hindered their use in large-scale constructions. At the end of the 20 th century, that limitation of wood as a building material would disappear with the emergence of what is known as gullam (i.e., glued laminated timber). This new material allows for large-span structures and provides great freedom of design. Glulam is created by bonding together layers of timber with a moisture-resistant adhesive, which makes it stronger and more stable than traditional timber. As a result, gullam has become a popular choice for architects and engineers in the construction of large buildings and structures [1]. Today, timber is seen as a key material for the sustainable future of construction, both for its technical and environmental qualities. Among its outstanding technical qualities, it is worth noting that timber is one of the building materials with the lowest weight-to-strength ratio. It has great insulating properties; a high degree of safety in case of fire due to the surface carbonization that is produced under the action of fire; and acts as an insulator, is easy to assemble, and has great aesthetic appeal, making it a popular choice for architects and builders [1]. Regarding its environmental qualities, timber is a renewable resource; it is one of the materials used in construction that requires less energy and emits less carbon dioxide in its manufacturing process [2; 3], since, to obtain it, continuousreforestation with growing trees is necessary, which guarantees the continuity of carbon dioxide sequestration and thus contributes to reducing the greenhouse effect [4]. In addition to its advantageous characteristics, timber is of great agro-industrial interest, as it is still used today as a structural element in cellars and other agricultural constructions inspired by traditional agricultural constructions. Nevertheless, a deeper understanding of timber structure optimization could promote its use in a wider range of projects and applications. The optimization of structures involves finding the most cost-effective structural design by minimizing the amount of material required that, at the same time, meets the predefined criteria, such as strength, stability, and displacements within the structural design and safety standards. Although research on structural optimization dates back to the 1970s [5; 6; 7], only in the last two decades has there been significant progress in its development [8; 9; 10; 11; 12], largely due to the implementation of artificial intelligence techniques such as genetic algorithms. However, most of the research focuses on steel [13; 14; 15; 16] and concrete [17; 18; 19; 20] structures, with timber structures [21; 22; 23] largely ignored by the scientific community. Nonetheless, there are some references studying the optimization of timber trusses using the mixed integer non-linear programming method [24; 25], prior to the development of the current Eurocode 5 [26; 27], which establishes the design rules for timber structures. In order to improve on the earlier attempts at optimization, [PERSON] et al. [28] addressed the two-dimensional optimization of timber trusses by programming genetic algorithms according to the Eurocode 5 [26; 27] requirements. Later on, the authors extended the previous investigation; the optimization was carried out on a three-dimensional roof structure composed of glulam trusses with purlins arranged accordingly [29]. Both papers were based on cost optimization, taking into account the high manpower required for triangulated structures as well as different geometric configurations.