Experimental investigation of the lateral loading response of a full-scale timber structure combining different bracing systems

Abstract

Timber structures often combine multiple lateral load-resisting systems whose interaction under serviceability loading remains insufficiently understood. This study presents a full-scale experimental investigation into the lateral response of a single-storey timber mock-up comprising lightweight timber frame wall diaphragms, a roof diaphragm, and a centrally positioned moment-resisting frame. Two loading scenarios (both in serviceability limit state to understand its initial, pre-yield behaviour) were examined, in which a horizontal load was applied at the roof diaphragm level: one without additional vertical load (Test-1) and one with a uniformly distributed roof dead load of 1 kN/m 2 (Test-2). Extensive instrumentation enabled a detailed assessment of load distribution, deformation behaviour, and system interaction. The results show that the lateral response is governed mainly by the interaction between the structural components rather than the summation of their individual stiffnesses. Without additional vertical load, the timber walls carry most of the horizontal load, while the moment-resisting frame (MRF) engages only at higher load levels. When a vertical load is applied, friction between the roof and walls increases significantly, reducing overall deformation and leading to a more stable, uniform load distribution. In this case, a large part of the horizontal load is dissipated through friction, and the relative contribution of the MRF remains limited, although more consistent throughout loading. Despite identical detailing, the wall diaphragms exhibited markedly different stiffness and deformation responses, highlighting the sensitivity of full-scale timber systems to construction tolerances and boundary conditions. Overall, the findings demonstrate that vertical dead loads must be considered when assessing the lateral response of timber structures.