Title: Local effects of bonding on the strength of drystone masonry in Iron-age brochs

Authors: Dimitris Theodossopoulos; Jenny Gilbertson; Wei He; Katherine Primavesi; Bowen Qiu; Franziska Reutter

Addresses: Architectural Technology and Conservation, ESALA, University of Edinburgh, 20 Chambers Street, Edinburgh EH1 1JZ, UK ' Northern Lighthouse Board, Edinburgh, UK ' STRABALA+ architecture, Shanghai, China ' Hitachi Europe Ltd, London, UK ' International Research Centre for Architectural Heritage Conservation, Shanghai Jiao Tong University, Shanghai, China ' Freeletics, Munich, Germany

Abstract: Collapses in drystone prehistoric Scottish broch towers probably started from localised failures at the supports of roofs or decks, settlements, ill-conceived modifications or gradual decay producing long-term accumulation of debris. Another source of instability is their precarious state during excavations. Some of these effects have been simulated as excessive lateral thrust or settlement and are studied here through experimental analysis on wallettes in 1/15 scale, expanding on earlier insight from complete broch models tested to settlement. Wallettes in typical bonds were tested following a parametric study on the effect of thickness, bond and architectural features (openings, corbelled chambers, uneven supports). Failure patterns at overturning and settlement were established triggered at a minimum lateral displacement of one-fifth of the wall thickness. The walls could resist a lateral earth pressure representing debris accumulation at least five times their active earth pressure and resistance to settlement was by arch formation at the base.

Keywords: brochs; drystone masonry; settlement; lateral earth pressure.

DOI: 10.1504/IJMRI.2023.134183

International Journal of Masonry Research and Innovation, 2023 Vol.8 No.6, pp.611 - 634

Accepted: 18 Feb 2022
Published online: 13 Oct 2023 *

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