3.3. Element Location Tolerances

3.3.1. Is a tolerance on hole or hole pattern location specified in the AISC Code of Standard Practice?

No. Neither the ±1∕16-in. tolerance, where applicable, on overall length of members framed to other steel parts nor the 1∕16-in. clearance on size of standard holes should be construed as implying that the tolerance of ±1∕16 in. also applies either to the maximum tolerance on hole location within a pattern of holes or to the position of intermediate connections.

3.3.2. What is the tolerance on location of intermediate and longitudinal stiffeners?

When intermediate stiffeners are spaced at a distance that is approximately equal to the girder depth, weld shrinkage up to 3∕8 in. in a 100-ft-long girder is not uncommon. Furthermore, thermal expansion or contraction in a like length of girder due to a temperature differential of 50 °F can cause a change in length of approximately 3∕8 in. In view of these and other factors, there is a need for a tolerance on the location of longitudinal stiffeners. Because AWS D1.1 Clause 5.23 is silent on this subject, AISC recommends the following criteria:

1. Intermediate stiffeners may deviate from their theoretical location ±2 in. as measured from the closest girder end.

2. Diaphragm and other connection stiffeners may deviate from their theoretical location by no more than twice the thickness of the stiffener.

3. Longitudinal stiffeners may deviate from their theoretical location by a distance equal to 1% of the girder depth.

4. If longitudinal stiffeners are interrupted by vertical stiffeners, the ends should not be offset by more than half the thickness of the longitudinal stiffeners.

3.3.3. When forces are to be transferred by contact bearing, is a gap allowed between the contact surfaces?

AISC Specification Section M4.4 states: “Lack of contact bearing not exceeding a gap of 1∕16 in., regardless of the type of splice used (partial-joint-penetration groove welded or bolted), is permitted.” If the gap exceeds 1∕16 in. but is less than ¼ in. and an engineering investigation shows that the actual area in contact (within 1∕16 in.) is adequate to transfer the load, then the gap is acceptable. Otherwise, per AISC Specification Section M4.4, the gap must be packed with non-tapered steel shims.