“The load-bearing performance of CLT wall elements in full-scale fire tests.”

Cross-laminated timber (CLT) is increasingly used in medium-rise timber buildings, among other reasons for rapidity of construction, cost effectiveness and robustness. Like for other building materials, the verification of the load-bearing performance in fire conditions is an important issue. The standard procedure to verify the fire resistance of CLT-wall elements in Europe is tests according to EN 1365-1. At SP (Technical Research Institute of Sweden) and IVALSA (Trees and Timber Institute, Italy) in total six loaded full and large-scale tests of CLT-wall elements, respectively, were performed. The aim was to gain information about initially protected and unprotected elements to be used for classification as well as for validation of calculation models. In the test series, reference tests at normal temperature were included to obtain information about the material tested in fire condition. Furthermore, model-scale fire tests were performed to investigate the loss in stiffness due to fire exposure and different protection types. In general, the load-bearing capacity of the tested CLT elements in the large and full-scale varied in the range 41,8 to 120 minutes depending on the CLT build-up, the leval of load, and the type of protection.