Using instrumented small-scale models to study structural load paths in wood-framed buildings

• We develop a 1/3rd scale model of a light-frame wood structure to determine structural load paths.
• We followed proper similitude scaling requirements to model all of the building components.
• The scale structure is instrumented at roof-to-wall and wall-to-foundation connections.
• Influence coefficients (i.e., load paths) were determined for these connections due to wind uplift loading.
• The structure was validated with full-scale data and results presented in the literature.

A large 1/3-scale model of a light-framed wood structure was constructed in order to study the structural reactions to wind loads in a three-dimensional model of a residential building. Thirty load cells measuring structural reactions at roof-to-wall and wall-to-foundation connections were used to determine influence functions in response to surface pressures generated by extreme winds. The influence functions are used in a database-assisted design (DAD) methodology to estimate failure loads in structures subjected to spatio-temporally varying wind loads. Current numerical methods based on 2D component models alone can lead to underestimated failure loads and inadequate designs. This paper describes the approach to develop the physical models and to validate their applicability to full-scale houses. Non-dimensional modeling techniques are explained, and scale model material properties for sheathing, wood-framing members, nails and truss-plate connections are provided. The need for a robust experimental method for determining influence functions is critical as load distributions are unpredictable in these structurally indeterminate systems. Further, the 1/3-scale physical models provide an economical approach to generate a large dataset of empirically-based models needed to cover a wide variety of geometrically complex houses and to calibrate non-linear numerical analysis programs for further DAD studies. The approach introduced in this study can be applied to more complex roof geometries and also to study the combined effects of horizontal and vertical wind load distributions in wood buildings.