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Teaching of Structural Analysis Into the Future

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Teaching of Structural Analysis Into the Future Civil Engineering Research in Ireland 2020 Teaching of Structural Analysis into the Future Dermot O’Dwyer, Department of Civil, Structural and Environmental Engineering, Museum Building, Trinity College Dublin, Ireland email: [email protected] ABSTRACT: The curricula of modern engineering programmes achieve a greater number of learning outcomes and cover a broader range of subject areas than ever before. This has resulted in a reduction in the hours that are available to teach structural engineering. At the same time the work of graduate structural engineers has changed and is likely to change further in the future. This paper considers what the kernel of essential knowledge for structural engineering should contain. More specifically it explores what elements of this kernel must be taught in university. The paper does not result in a definitive list of topics but makes some initial suggestions and promotes a rationale by which such a list might be arrived at. The paper argues that it is import to acknowledge that much of structural engineering analysis is pragmatic. Many of the basic theories are simplifications that are useful only in certain circumstances with certain materials. This complicates identifying a small set of structural engineering rules, Newton’s Laws excepted. While structural engineers should have knowledge of mechanics of solids, elasticity and methods of analysing statically indeterminate structures the level of complexity that needs to be achieved is not immediately clear. Modern structural engineering practice suggests that some areas of structural engineering analysis, such as the flexibility method, are obsolete; however, some of these methods are useful for exploring important concepts and developing qualitative analysis skills. Qualitative analysis skills are vitally important because most structural analysis is performed using computer software and it is essential that an engineer is able to critique the output from such programs. Qualitative analysis is a key skill in structural design. The paper also considers how the role of structural engineers is likely to change with the increased use of artificial intelligence and machine learning, and with the development of parametric modeling packages that allow engineers to vary the form of a structure and observe the changes in structural response instantly. The paper also considers whether there is a need for different objectives when it comes to selecting topics that should be taught at undergraduate and at postgraduate level. Undergraduate curricula should ensure basic competence: equilibrium of forces, the relationship between stresses and strains and knowledge of the failure mechanisms for different materials and structure type etc. Should postgraduate curricula be designed to ensure that knowledge of a wide variety of specialist techniques, such as: fracture mechanics, classical elasticity, continuum mechanics, structural optimisation, design and analysis of plates and shells etc. are maintained within the engineering profession? From this basis the paper tries to address the core competences that every structural engineer should have as well as the core knowledge that would be essential for students to further develop their knowledge of structural engineering once they have graduated. KEY WORDS: Engineering education; Structural Engineering; Structural analysis; Structural design; Engineering Curriculum; Future. 1 INTRODUCTION taught in college are rarely used in practice. As a result the structural engineering curriculum is changing. This paper This paper is intended to be the starting point in a discussion on considers what the core curriculum for structural engineering what should be included in current and future structural should contain. engineering curricula. This is not a trivial question. While some traditional analysis The engineering curriculum has always been full. In the past methods, such as graphic statics, can be omitted without civil and structural engineers studied a wide variety of technical significant consequences the loss of other types of hand subjects within the broad field of engineering science and spent analysis, such as influence line diagrams, may hinder students many hours working on design projects. Modern engineering developing a full understanding of structural behavior. curricula try to cover these areas while also dedicating more Similarly, while all structural and civil engineering time to structured group-work, report writing and students must have a knowledge of mechanics of solids, what communication skills. Although students spend longer in aspects of mechanics of solids are core? As structural college, the number and range of technical fields that engineers embrace an ever wider variety of materials should students must master is considerably broader than in the past. mechanics of solids and mechanics of materials be studied in As a result the time available to teach structural engineering greater detail? Should the emphasis on linear-elastic matrix has reduced. At the same time the work of a structural engineer methods move from teaching the basic algorithms to an has changed and some methods of analysis and design that increased emphasis on were traditionally 429 Civil Engineering Research in Ireland 2020 understanding and overcoming the limitations of such forget that this theory is a combination of three separate methods? Where does plastic analysis fit when most structural concepts. These are: analysis is performed using linear-elastic theory? What will the core skills of a civil/structural engineer be when structural 1. The internal forces in a beam must be in equilibrium designs can be developed by autonomous algorithms that take with the externally applied loads. 3D general arrangement models as their input? 2. The internal forces developed in the beam are related to internal deformations of the material in the beam. 2 STRUCTURAL ANALYSIS & PRAGMATISM 3. The beam fails when the internal forces (stresses) or It is possible to interpret the history of the development of internal deformations (strains) exceed the capacity of structural engineering as the gradual development of ever more the material the beam is formed from. sophisticated mathematical models [1,2,3,4,5,6]. This interpretation is correct but it is not necessarily complete. This The first point, which was understood by Galileo and was given is an important point to consider because it is easy to imagine in a general form by Coulomb in the 1770s is clear today but that the core canon of structural engineering is fixed. This is not was poorly understood for many years [7]. Coulomb necessarily the case. specified the need for the internal forces along the section A- D in Figure 2 to be in equilibrium with the applied load. He Engineers Bending Theory stated that the longitudinal stresses must develop an internal Consider engineers’ bending theory, which is arguably among moment and that there was a need for forces with a the most useful structural engineering theories. It began with vertical component to counteract the vertical load. the work of Galileo, and was developed by Marriott, James and However, the discussions following James Barton’s Daniel Bernoulli, Euler, Coulomb, Hodgkinson, Navier and paper on the Boyne Viaduct to the ICE in 185 5, shortly others. Figure 1 shows a sequence of assumptions of how the before Jourawski’s work on shear was published in 1856, internal longitudinal stresses are distributed in a cross-section shows how the shear forces in a beam were poorly understood of the base of a cantilever [3]. [8,9]. Figure 2. Equilibrium of the internal forces and external loads [7] Regarding the second point, the relationship between stress and strain in a beam made from an elastic material is far more complex than = . This formula and the familiar = work well for simple steel universal beams but with larger plate girders effects such as shear lag must be considered. The third concept, that of material failure criteria is also treated in a very simple manner when designing steel beams. It is notable that when designing other components it is often essential to consider the full stress and strain tensors and to take account of fracture mechanics and fatigue. The important point is that many of our analysis methods are based on assumptions that are not universally true. There is often a conflict between teaching as much “useful” material as possible and ensuring that the underlying assumptions are covered in detail. One particularly relevant example is the use Figure 1. Stress distributions and calculated moment of elastic methods, and computer programs based on elastic capacity of a cantilever [3]. methods, to calculate the internal forces in reinforced concrete structures. This procedure is justified by the safe The wonder to a modern engineer is that the final “correct” theorem of plasticity but many engineers today learn solution took so long to emerge. However, engineers today elastic analysis without getting a thorough grounding in have the benefit of hindsight and typically use structural plastic theory. materials that have well defined properties. The profession is In the past structural analysis was not as essential as we so comfortable with engineers’ bending theory that it is easy to consider it today. The gothic cathedrals were constructed without formal calculation, although being based on arches it was 430 Civil Engineering Research in Ireland 2020 possible for their builders to rely on models to ensure
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