Assessing the Contribution of Plank Walls to Lateral Load Resistance in Heritage Timber Frame Barns

Abstract

Heritage timber frame barns are historically and culturally significant buildings, yet their structural properties are often poorly understood. Lack of research leads to overly conservative assumptions being made during structural evaluations for interventions, in turn triggering repairs that can be expensive, invasive, and unnecessary. Load sharing between the frame and building envelope is a particular aspect of these structures that is conventionally neglected. This study presents a modal analysis and model updating procedure to quantify the contribution of a vertical plank wall system to shear stiffness and lateral load resistance in the sheep barn at Howell Living History Farm. The results show that conservative frame-only models greatly underestimate the structure, accounting for only 26% of its stiffness and generating post moments over three times as great as combined models with the building envelope. Based on these results, an approach is proposed to better model these structures, using a homogenized surface area element representation of the building envelope tuned via iterative stiffness updating. This approach offers a practical and physically grounded framework for future modeling of heritage timber frame barns with vertical plank siding, better informing engineering assessments of lateral load resistance to avoid costly and unnecessary repairs.