Johansen’s yield model—a widely adopted design model for determining reference lateral design values for wood member connections in heavy timber and mass timber construction—is mandated for use by regulatory authorities in both Europe and North America. However, its origins in tests conducted with earlier-generation wood materials and fastening technology pose limitations to its contemporary employment. Notably, the model does not adequately address the susceptibility of certain wood species and engineered wood products to splitting, nor does it consider the influence of connection geometry. Consequently, the estimates it provides may not consistently align with actual performance in modern mass timber applications. This drawback underscores the necessity for remedial considerations in practice.
While Johansen’s yield model continues to be a crucial tool for determining reference lateral design values for shear connections, a requirement upheld across jurisdictions, its limitations in accounting for material and geometric factors can impede desired structural performance. One approach to counter splitting issues, often encountered with fastener placement near stressed edges but unaccounted for in Johansen’s model, involves integrating vertical reinforcing fasteners in close proximity to the point of stress initiation. This addition not only addresses the innate material concern but also enhances the reliability of anticipated load distribution behavior, thus safeguarding against unforeseen complications. This solution mirrors a well-established reinforcement practice in concrete structures, advocating for the widespread adoption of reinforcing fasteners in analogous situations within mass timber construction.
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