Stiffeners In General

Bearing Stiffeners
Plain, Intermediate Stiffeners
Diaphragm Connection Plates

There are several types of stiffener errors, the most common of which are misplaced stiffeners, incorrect hole placement, and improper stiffener to flange attachment. Repairs to errors will vary, depending on the type of stiffener. (Bearing, Plain Intermediate, or Diaphragm Connection).

Timing is important when making decisions about repairs. If an error is caught after the stiffener has been tacked into place, but before it has been completely welded, it is not too difficult to remove the stiffener and resolve the error. After the stiffener has been fully welded, removing it becomes a much less desirable option.

Occasionally, a diaphragm connection plate or stiffener is welded to a tension flange in an area where that is prohibited. Usually inspectors require the fabricator only to break the weld, and install the bolted connection in accordance with the design plan. A solution to this type of problem is still under development so this paragraph of this tutorial is incomplete.

Changes in design requirements in recent years have added to the types of errors than can occur with stiffeners. The diaphragm connection plates must always be attached to the tension flange. Usually welding is not allowed. Errors that are made at the compression flange attachment are generally easy to fix. Errors at the tension flange are not. If holes are inadvertently drilled in a compression flange, they can either be filled with bolts, or a connection can be made identically to those used on the tension flange.

Holes are sometimes drilled in the wrong locations in the tension flange. Usually, the best repair when this happens is to custom fabricate a direct attachment to fit the holes as they are drilled in the flange.

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