The construction industry contributes to approximately 40–50 percent of greenhouse gas emissions. This figure includes both the energy consumed during building operations on site and the energy used in the manufacturing of construction materials and products.
Two main strategies have been thoroughly investigated to mitigate the environmental impact of building elements: structural optimisation by minimising the elements’ section and the use of low-carbon materials. This is the reason why wood and wood products such as glued laminated timber are valued and have gained success as a construction material nowadays.
Glued laminated timber, known as ‘glulam’ or GLT, is a composite material made of overlapping layers of wood bonded with synthetic resins and pressed into the desired shape. This type of product is one of the most popular options in civil engineering—while the ability to absorb carbon from the environment makes it a sustainable material.
Additionally, the good mechanical properties of the material along with its low self-weight make it a great seismic performance solution.
The production of GLT elements represents a major advantage in terms of reducing workmanship on site, through the quality of the machined elements and the obtaining of complex geometries with various sizes that can be customised to meet individual specifications and requirements.
The design and execution of civil structures is, however, still dependent on inertia in terms of the geometric dimensioning of structures, which favors constant rectangular sections, easy to size.
Another significant advantage of wood is its strength-to-weight ratio when compared to materials like concrete and steel, making it an excellent choice.
Reducing the weight of the element diminishes the dead loads along with the size of elements in the structure.
Recent Studies Progress
Recent studies have shown that topological optimisation can lead to better dimensions of the element able to support the forces applied.
According to existing studies in the field, the characteristics of the model resulting from different types of analysis in the Finite Element Method, simple regression on metamodels, tests on models or by Monte-Carlo simulation may produce material reductions of over 10 percent.
The topological optimisation is used in a multitude of fields such as aerospace field (for application in the manufacturing process); robotics (in order to reduce the weight of the product, while maintaining the mechanical properties); medical devices (for the shape of the element), the energy and battery life, cases where different scenarios were considered with the variation of geometric dimensions and structural properties, architecture; and civil engineering which was the focus in this current research.
Optimisation model examples are presented where structural analysis and dimensioning constraints defined by Eurocode standards are used in order to create a model of profiles that can reduce the cost of a building with elements made of glued laminated timber and steel.
Moreover, the study of "Introduction to Lightweight Structures" from Ochieng, D. Kiu Publication Extension, demonstrates that optimisation techniques reduce the mass of elements up to 30 percent creating high-performance with low-weight design and reduction of deflection by 15–20 percent. The variation in geometric dimensions of elements, materials, curved elements with large span, height and volume of buildings creates new designs where the elements can be used in a rational manner, reducing the manufacturing process and the cross sections while maintaining the resistance.
At the same time, during the current research campaigns, topological optimisation can be carried out using AI that gives new perspectives and a multitude of possible scenarios.
The methods mentioned above improve cost efficiency and optimise the mechanical performance of structural elements in GLT. However, they derive from analyses that require financial resources, whether in laboratory experiments or through time-consuming programs.
This happens considering that the operation research processing on models using the Finite Element Method (FEM) involves systems solving inequations having as input data the results of the FEM and the geometry variation until the objective function is reached.
This is the current scientific context, where the premises exist for the use of machine learning techniques in order to embed geometry and structural behaviour data obtained by topological optimisation and to reduce the computation requirements for the deployment of such a solution.
Techniques such as deep neural networks or generative adversarial networks have already proven useful for this kind of application. The part this paper addresses is the training data for such an algorithm.
The success of any development in this direction depends on the quality of the training data; for example, the present project proposes some domain limits for the exploration of topologically optimised solutions and presents an algorithm for computing this kind of optimisation task, using the Dassault ABAQUS 2023 software package.
Experimental Campaign And Test Equipment
For the experimental campaign, GLT elements were used in the experiments and tested as well as their combination to ascertain the contact properties.
In terms of the wood species used, spruce was the best solution considering that it is a common species used for the realisation of glued laminated timber elements according to the study of "Metamodel assisted optimisation of glued laminated timber beams by using metaheuristic algorithms" from Pech, S.,Kandler, G., Lukacevic, M. and Füss, J..
The GLT elements are formed by joining together layers of wood material in the form of lamellas with the thickness
