Abstract
Non-destructive field measurement campaign consisting of two parts: (1) dynamic identification tests and (2) timber elements assessment, was conducted on the 18th century timber wharf building made of Norway Spruce in Trondheim, Norway. Currently, the building is undergoing restoration, and the goal of the field measurement campaign is to carefully assess the structural condition of the building while restoring it as closely as possible to sufficient strength for adaptive reuse. Dynamic identification was conducted by measuring ambient vibrations of the wharf using wireless tri-axial accelerometers and a wireless gateway for sensor synchronization and data aggregation. Stochastic subspace identification was used to determine the modal properties of the building: the natural frequencies and mode shapes. Non-destructive tests of selected beams were carried out using ultrasound time-of-flight, experimental modal analysis, and sound wave time-of-flight methods to estimate local material properties, i.e., dynamic elastic modulus. In addition, a resistograph was employed for in-situ density estimation, while a LIDAR scan was used to determine the volume of the structural elements. The results of the field measurements were used to develop the numerical model of the wharf in FEA software Abaqus. The mechanical properties estimated through the non-destructive testing were used for timber material model. The identified natural frequencies and mode shapes of the building were subsequently compared with those from the numerical model of the wharf building. Historic timber buildings possess not only important cultural value but are also benchmarks for gathering information about the future adaptive reuse of buildings, where assessment of existing mechanical properties is important to allow for service life extension with minimum intervention and costs.