A common model of light gauge, metal joist hanger is tested on a wood-to-wood connection for two conditions. One condition follows the commonly used test standard for joist hangers, which allows the support beam to be restrained from horizontal and rotational movement. The second condition (unrestrained) allows the support beam to freely move horizontally and in rotation. The results show that the unrestrained case is much weaker than the standard restrained case. For the model of hanger tested, the average ultimate load for the unrestrained case was 28% of the standard restrained case. The mode of failure for the unrestrained case is different than that for the restrained case. This documents the importance of providing means of restraining the supporting beam by methods other than the connection via the joist hanger. The ASTM testing method for joist hangers may need to be adjusted to account for this possible mode of failure.
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