Background

The American Institute of Steel Construction (AISC) and its Hollow Structural Shape (HSS) Committee is formulating a proposal to the American Society for Testing Materials (ASTM) for a new standard for HSS members and their constituent materials. There are concerns that the new standard and some of its provisions are not consistent with mass and dimensional tolerances of HSS members supplied by producing companies and modern manufacturing techniques. As a result, the AISC sought further information with regard to the dimensional variability in HSS members so that the proposed standard and provisions within it are not unduly punishing to HSS manufacturers/suppliers. This additional information can also be used by the AISC specification committee to better understand the impact of these standard provisions on the design specification. Finally, a relatively recent conference publication (Poag and Zervoudis 2003) highlighted concerns that cracks may form in the corner region of HSS member cross-sections resulting severe cracking during galvanizing processes.

The proposed research effort can be classified as a pilot study that intends to characterize the variability of cross-sectional dimensions and design-related cross-sectional parameters for HSS members and evaluate the tendencies for cracking in the corners of HSS members. The results of the research will provide the AISC HSS Committee better information for the proposed ASTM standard and will also provide the AISC specification committee with valuable information related to cross-sectional variability in HSS members that can be used to influence design specification provisions.

The objectives of the pilot study are: (a) characterize the variation in HSS wall thickness for a representative sample of HSS members provided by HSS producers: (b) characterize the mass variability present in the sample; (c) characterize the variability of parameters used in the specification provisions (e.g. D/t, B/t, R less than or equal to 3t) for the representative sample; (d) characterize the variability in wall thickness to address the suitability of the inherent 0.93t limit on cross-sectional thickness present in the specifications; (e) characterize the variability in flat-to-flat dimensions of HSS members; and (f) examine the HSS member cross-sections for cracking present at the corners of the HSS shapes provided.

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