Scaling effect on the moment and shear responses of three types of beam-to-column connectors used in mass timber buildings

•Scaling effect investigated on timber beam-to-column connections.•Full-scale and ¼-scale down connections showed similar failure modes.•Full-scale and ¼-scale down connections showed similar non-linear responses.•¼-scale down connections tended to have higher capacities, typically 20% higher.•Scaled down timber systems accurately replicate the behaviour of full-scale systems. To fully understand the structural behaviour of large structural systems under given loading scenarios, experimental testing of the entire system or of a representative part of it is often required. However, due to limited laboratory space and budget restrictions, tests are frequently performed on scaled down systems. The scaled tests allow investigating the influence of a large number of parameters, therefore providing in-depth understanding of the structural system response, an opportunity rarely achievable in full-scale testing due to cost related issues. As timber is known to be sensitive to size effects, it is unclear (i) how accurately tests performed on a scaled down timber structure would reproduce the full-scale system response and (ii) how scaled tests results must be interpreted to consider the scaling effect. This paper experimentally investigates the full-scale and quarter-scale moment and shear non-linear responses of three types of beam-to-column connectors currently used in post-and-beam mass timber buildings. Moreover, the paper discusses (i) how tests performed on scaled down timber buildings can be extrapolated to full-scale structures, and (ii) presents recommendations for the scaled down specimens to best replicate the response of the full-scale ones. A total of 12 full-scale and 18 quarter-scale tests were performed. Considering the scaling factor, results show that the overall non-linear responses of the quarter-scale connections closely match the full-scale responses. However, still taking into account the scale factor: (i) the average ratio of the quarter-scale to full-scale elastic stiffness is 0.74 and (ii) the tests performed on the scaled down connections typically result in a capacity 1.2 times higher than the capacity of the full-scale systems. Results also demonstrate the importance of using steel or aluminium connectors with similar material ductility in both the scaled down and full-scale connectors.