Residual Stress Measurement of Built-Up I-Section Members via the Center-Hole Drilling Method
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Abstract
The objective of this study was to measure the residual stresses of two built-up I-girders (one
doubly symmetric and one singly symmetric) that are representative of all the experimental
specimens tested in the lateral torsional buckling (LTB) investigations conducted by Slein et al.
(2022) and Phillips et al. (2022). The measured residual stress profiles were compared to the
one-half Best-fit Prawel residual stress profile used in a series of complementary shell finite
element analysis (FEA) simulations conducted by Slein et al. (2022), Deshpande et al. (2021), and
Phillips et al. (2022).
Residual stresses are introduced into components during the manufacturing and fabrication
processes and are independent of any externally applied forces or thermal loads. Resulting from
mechanical, thermal, and/or metallurgical processes, residual stresses are introduced into built-up
I-girders during the manufacturing of the individual plate elements and the welding of the plate
components during fabrication. The residual stresses are self-equilibrating, meaning that the
corresponding cross-section tensile and compressive forces must balance across the section.
Applied stresses are additive to the residual stresses. For the stability limit state, compressive
residual stresses at the flange tips have a detrimental impact on the overall buckling strength of the
member due to the resulting premature yielding.
Two primary classifications for residual stress measurement techniques exist: destructive and
non-destructive. Destructive techniques involve the process of removing a small volume of
material and then measuring the resulting strains, while non-destructive techniques involve using
grain structure and material properties to measure the internal stresses of a member without any
physical alterations. For the current study, the semi-destructive technique of center-hole drilling
was selected. Center hole-drilling is semi-destructive as it involves the removal of a volume of
material, but the holes are generally small enough that they could be repaired without hinderance
to the performance of the specimen. The center-hole drilling technique is described in detail in
ASTM E837 (2020). All the measurements performed during the current work were conducted in
accordance with the governing standard.
The measured residual stress profiles for the two specimens considered were small. All flange
measurements resulted in a similar profile, where the outer thirds of the flange widths had littleto-
no residual stress and the middle third had a spike in tensile residual stress apparently associated
with the web-to-flange weld. Both the webs demonstrated an approximately uniform compressive
residual stress throughout the web. The measured stresses suggest that the one-half Best-fit Prawel
distribution provides a reasonable-to-conservative estimate of the residual stress profiles of the
evaluated members; hence the use of the one-half Best-fit Prawel distribution is justified for the
complementary shell FEA simulations.
Sponsor
Metal Building Manufacturers Association (MBMA); American Institute of Steel Construction (AISC); American Iron and Steel Institute (AISI)
Date
2022-05
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Text
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Technical Report
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