Analysis of the charring behaviour of heritage timber using digital image correlation

Heritage buildings represent centuries of human evolution and have immense cultural and social value. Timber is one of the oldest construction materials, and a fundamental element of many historic buildings. Exposure to the natural elements and the process of aging over many centuries reduces fire resistance in heritage buildings compared to modern timber. Despite preservation attempts, fire damage continues to affect heritage timber buildings, often leading to complete destruction. Recent examples include Notre Dame (France), Shuri Castle (Japan) and Vondelkerk (Netherlands). The presented work applies image analysis to monitor charring behaviour of an Eastern Hemlock connection tested using an open pool fire. The influence of the lighting during the test, as well the location of the heat source and the defects present on the member, is observed and analysed. It is established that the presence of blue LED light changes the colour characteristics of the charred pixels. Additionally, results indicate that the fire source location influences the surface charring more than the presence of defects.