Reduced-scale models as strategy for improving the undergraduate learning process in the field of structural engineering

Resumen

In the context of civil engineering undergraduate courses, the analysis and design of engineering structures is one of the competences to be acquired by the students. All the knowledge fields of continuum mechanics with applications to civil engineering, such as the fluid mechanics, the soil mechanics, or the structural engineering, involve a high amount of advanced mathematical and physical concepts. Such concepts lie mainly in the structural kinematics (i.e., the structural displacements and strains) and the associated internal forces (or stress distributions). In the last two decades the understanding and application of these concepts has usually required additional strategies, such as the use of numerical software applied to the simulation of structural systems, the development of lab tests about the mechanical properties of several standard materials (such as steel, wood, concrete or another composite materials) or the in-situ structural analysis of real civil constructions. However, students usually focus on the methodology, hence reducing the correct interpretation of the physical concepts that underlay at each structural model. In fact, such methodology is frequently reduced to be a set of several recipes or rules that only assist to the students in the calculation of standard structural types. Due to these previous reasons, and over the teaching experience of the authors, this work pretends to bring out the great usefulness of the reduced-scale models for the full understanding of the structural kinematics, considering the influence of the constitutive material in the stress-strain response of each structural member. To this aim, a set of structural models were performed in a lab, through the implementation of several electronic devices that allow controlling the application of different types of forces or imposed displacements, as well as the measurement of principal strains at critical member sections. This type of systems was developed for both static and dynamic analysis (including, for example, seismic loads or wind effects); in the second case, the main parameters of a dynamic model, such as the structural mass or the viscous damping, were adequately monitored. As result, students were able to check the response of a structural type in a reduced-scale context, based on the previous calculation of the displacements and load parameters from a theoretical formulation. All these actions provided to the students not only the direct perception and understanding of the structural response, but also the opportunity of evaluating, at least in a qualitative way, the goodness of the corresponding theoretical analysis. Finally, this type of strategies encourages the understanding of the conceptual basis in a structural model, before than its methodology and even, its mathematical formulation, which largely trains the analytical capabilities of students with respect to structural behaviour.