Element location tolerances is a tolerance on hole or

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Element Location Tolerances Is a tolerance on hole or hole pattern location specified in the 2000 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 ±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. 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 shrink- age up to 3/8 in. in a 100-ft-long girder is not uncommon. Furthermore, thermal expansion or contraction in a
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PAGE 15 APPENDIX like length of girder due to a temperature differential of 50° Fahrenheit can cause a change in length of approx- imately 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 D1.1-2000 Section 5.23 is silent on this subject, AISC recommends the following crite- ria: 1. Intermediate stiffeners may deviate from their theoretical location ±2 in. as measured from the 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 percent 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. When forces are to be transferred by contact bearing, is a gap allowed between the contact surfaces ? From the 1999 AISC LRFD Specification Section M4.4, "Lack of contact bearing not exceeding a gap of 1/16- in. (2 mm), regardless of the type of splice used (partial-point-penetration groove welded or bolted), is permit- ted." If the gap exceeds 1/16 in., but is less than 1/4 in., and an engineering investigation shows that the actu- al area in contact (within 1/16 in.) is adequate to transfer the load, then the gap is acceptable. Otherwise, per the 1999 AISC LRFD Specification Section M4.4, the gap must be packed with non-tapered steel shims. Similarly, a tolerance of 1/16 in. for bearing stiffeners is allowed in AWS D1.1-2000 Section 5.23.11.1. Such a gap would presumably be closed under load, bringing the stiffener into full contact bearing. Erection Tolerances How do individual member deviations impact the alignment and erected position of the overall structural steel frame ? In many cases, individual member deviations that exceed established tolerances will have no adverse effect on the overall structural steel frame. However, in other instances, individual member deviations may accumulate and cause the overall structural steel frame to substantially exceed the overall permissible tolerances for plumbness, level, and line. It is essential that the effect of individual member tolerances on the overall structural steel frame
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