Monitoring and assessing structural damage in historic buildings

Abstract

In the cultural heritage field, the monitoring of the integrity of structures can greatly benefit from 3D digitising techniques. The aim of deformation analysis and structural surveillance is the early detection of damage in order to be able to react appropriately and in good time. The devices that have been traditionally used in the measurement of fissures, cracks and fractures are contact tools whose application depends on accessibility; moreover, they only provide discrete point measurements rather than giving a continuous record of the damage dimension in the whole affected area, as modern 3D modelling techniques can do. Among these techniques, close range photogrammetry is still the most complete, economical, portable, flexible and widely used approach in architectural applications. This paper is focused on the application of close range photogrammetry in the detection and monitoring of structural damage. The following procedure is proposed: the gathering at different epochs of 3D point clouds in the neighbourhood of cracks; the comparison among the successive point clouds by means of shape parameters; and the application of a bootstrap test for the detection of the significant statistical results. This procedure is applied to the analysis of structural damage detected in a masonry structure of cultural heritage interest: Basílica da Ascensión, located in the north-west of Spain. © 2008 The Authors. Journal Compilation © 2008 Remote Sensing and Photogrammetry Society and Blackwell Publishing Ltd.