Paper

(In)Determinacy: Material and Joint Constraints to Unleash Tectonic Thinking

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Abstract

Tectonics has been defined as the art of joinings. The focus on expressive potential of joints differentiates tectonic material systems, those built from multiple visible components, from atectonic material systems, those bonded or made solid by and, in some cases, indistinguishable from the joints. Kenneth Frampton’s account of the history of modern architecture through construction reinterpreted Gottfried Semper’s Four Elements as two categories of building crafts: the tectonics of the frame, that is the “lightweight linear components…assembled to encompass a spatial matrix” associated with tension; and the stereotomics of the earthwork, produced through “the piling up of the heavyweight elements” and associated with compression. That places wood and some metal assemblies in the first category, and cast-in-place concrete and masonry in the latter. Although joints are central to tectonic thinking, the implication of different structural methods of joining, and their primarily shear and friction forces, are mostly absent in the discourse. This paper argues that structural determinacy is an important differentiator between tectonic and atectonic expression by eliminating rigid joints. To test this idea, the constraint of determinacy was introduced through material choice in a design project for a Structural Systems course. Constraints are essential in any pedagogy to focus learning and avoid cognitive overload. For example, in previous years the course introduced constraints of program and site to focus structural decisions on load path patterns and hierarchy without added complexities of enclosure or type. Students could make material decisions based on conceptual drivers or interests, but the fear of complexity in the assignment resulted in many misguided and self-imposed limits. Students selected certain material and joint types, specifically concrete flat slabs or steel moment frames, believing it would simplify model making and diagramming of lateral systems, i.e. being able to ignore joints and their dynamic movement in detailing and the configuration of systems. The decision was quickly regretted once calculations with indeterminate rigid structures became too complex. This represented a challenge for this one-semester course—the only structures course in the curriculum—which limits content to determinate systems. This necessitated more one-on-one guidance, often with imperfect shortcuts that did not improve learning. To address this issue, a new iteration of the course introduced a new constraint of determinacy, requiring a wood structure where all joints are naturally pinned. The intention was to introduce more complexity in compositional design, physical modeling and details and, in turn, simplify the quantitative analysis. This paper draws on tectonics discourse to explain the pedagogical motivations and methods, analyze student learning outcomes and performance in comparison with previous iterations of the course, and share insights from student reflections. Findings suggest that the physical modeling of joints to simulate pinned behavior increased understanding of the torsional effects of configurations, increased student interest in the pragmatic and aesthetic implications of joint detailing, and in the context of wood, placed new and unprompted attention on the connection to the ground and its expressive potential. Refocusing on pinned joints motivated tectonic thinking, improved learning, and increased the quality of quantitative analysis.

Keywords: determinacy, structural systems, tectonics, joints, timber

How to Cite:

Laboy, M., (2023) “(In)Determinacy: Material and Joint Constraints to Unleash Tectonic Thinking”, Building Technology Educators’ Society 2023(1), 282-291. doi: https://doi.org/10.7275/btes.1965