Prestress in Nature and Technics
Licentiatavhandling, 2019

To direct the forces of nature is a central task in the creation of spaces and load-carrying structures for architecture. This research investigates how prestress can be used as a design tool for the creation of material efficient and well-functioning structures, and in early design stages contribute to sustainable, functional and beautiful architecture.

The thesis begins with a discussion about central concepts such as stress and stiffness. Stiffness can be understood as the sum of elastic stiffness and geometric stiffness and the latter is differently influenced by the presence of tensile or compressive stresses. Only structures that are statically indeterminate are possible to prestress so that the stress pattern is affected. The terms externally-equilibrated and auto-equilibrated prestressed structures are introduced.

The design of load-bearing structures for architecture requires a collaboration between architects and engineers and the conditions for a successful collaboration is reflected upon. Prominent design cultures are highlighted and the one this research is linked to is described.

A collection of historic and contemporary examples of prestressed structures is presented. The focus is architectural applications but examples from other realms are also included. From this collection, a framework for prestressed structures is proposed and discussed which considers five perspectives. The first explores the historical knowledge development. The second is devoted to structural mechanical modes of actions where material behaviour, member actions and structural systems are discussed. The third highlights computational strategies and those appropriate for early stage design are distinguished from those suitable for late stage verification. The fourth perspective seeks to establish objectives for why prestress is used. The fifth perspective leads to suggestions for strategies for how the prestress is achieved.

Three papers are included. Paper A presents a numerical method for the form finding of prestressed gridshells consisting of both compressed and tensioned members. Paper B describes a structural design process where methods usually applied by architects are used by structural engineers. The work resulted in the construction of a temporary pavilion consisting of a post-tensioned wooden gridshell called the Wood Fusion Pavilion. Paper C explores under what conditions an unloaded shell formed of a closed surface unattached to any supports can contain a state of membrane stress which can be induced by prestressing. It is concluded that a torus can be prestressed, but there must almost certainly be more to explore.

Geometrical stiffness

Prestress

Form finding

Architecture

Structural design

Stress pattern

Engineering

Conceptual design

SB-H4, Sven Hultins gata 6
Opponent: Adj. prof. Dr. Roberto Crocetti, KTH​, Sweden

Författare

Alexander Sehlström

Chalmers, Arkitektur och samhällsbyggnadsteknik, Arkitekturens teori och metod, Forskning - Arkitekturens teori och metod

Prestressed gridshell structures

Proceedings of the IASS Symposium 2017,; (2017)

Paper i proceeding

Sehlström, A., Isaksson, J., Skeppstedt, M., Lund, M., Ander, M., Gustafsson, J., Williams, C. J. K., Olsson, K-G. Embracing design methods from architects for conceptual design of structures

Unloaded prestressed shell formed from a closed surface unattached to any supports

Form and Force - IASS Symposium 2019 and Structural Membranes 2019,; (2019)p. 167-174

Paper i proceeding

On multi-objective topology optimization and tracing of Pareto-optimal structures

Proceedings of 29th Nordic Seminar on Computational Mechanics – NSCM29,; (2016)

Konferensbidrag (offentliggjort, men ej förlagsutgivet)

The use of virtual work for the formfinding of fabric, shell and gridshell structures

Proceedings of the Advances in Architectural Geometry conference 2018,; (2018)p. 286-315

Paper i proceeding

Moving Mesh and Image Registration in FEniCS

Proceedings of 30th Nordic Seminar on Computational Mechanics – NSCM30,; (2017)p. 180-183

Konferensbidrag (offentliggjort, men ej förlagsutgivet)

Ämneskategorier

Arkitekturteknik

Arkitektur

Geometri

Matematisk analys

Utgivare

Chalmers tekniska högskola

SB-H4, Sven Hultins gata 6

Opponent: Adj. prof. Dr. Roberto Crocetti, KTH​, Sweden

Mer information

Senast uppdaterat

2019-10-10