Drilling through or notching of TJI® joist flanges should be avoided. However, vertical holes drilled through the top flange of a TJI® joist sometimes occur. These holes are typically 1″ or less in diameter, and may be created by plumbers/electricians during the installation of tubing or wiring. ForteWEB™ has flange notch analysis capability and can assess the impact of the hole (input as a square cut notch with notch depth equal to hole diameter) for a given joist span/load scenario.
Small, top flange holes which occur over the end support for a TJI joist are acceptable without analysis as detailed in Figure 1 below. While ForteWEB notch analysis will show those situations ‘pass’, they also can be compared to a firecut joist end, which is an acceptable detail that does not require analysis. Firecut joists have tapered ends, with the top flange removed no further than the face of the bearing below.
In Figure 1 below a TJI joist is shown with end bearing at support #1 and continuing across support #2. Provided the top flange hole over support #1 does not extend past the face of bearing (indicated by the red dashed line), it is comparable to a firecut detail and therefore allowable. The hole occurs in the portion of the joist that could have been removed (the firecut). Note that the comparison does not apply to the flange hole over support #2 since the joist is continuous over the intermediate support and the flange may be highly stressed in that location. That situation can still be checked using ForteWEB.
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