Horizontal Support of Historic Roof Structures: Design and Structural Efficiency

Abstract

In historic buildings, a variety of different types of timber roof structures reflecting different building traditions and different ideals for the inner space are found. In Sweden, damage to historic roof structures due to a lack of support for horizontal thrust is common. Knowledge of the relation between structurally efficient horizontal support and the extension of a structure in space is essential for obtaining an adequate understanding of the development of building techniques and for making sound decisions concerning restoration. An approach that involves a classification of horizontal supporting structures, together with a mechanical model that defines and distinguishes between inner and outer support, is introduced, with the aim of offering a tool for comparison of different roof-truss designs with focus on the occupation in space. Comparison of the efficiency of different designs is carried out by comparing horizontal stiffness. Eleven different designs divided into four spatial groups have been analyzed.