Page 283 - Handbook of Structural Steel Connection Design and Details

Welded Joint Design and Production

268 Chapter Three

ensure complete crack removal before subsequent welding is per-
formed on damaged structures.
Ultrasonic inspection has become the primary nondestructive test-
ing method used for most building applications. It can be utilized to
inspect butt, T, and corner joints, is relatively portable, and is free
from the radiation concerns associated with RT inspection. UT is par-
ticularly sensitive to the identification of cracks, the most significant
defect in a structural system. While it may not detect spherical or
cylindrical voids such as porosity, the consequences of nondetection of
these types of discontinuities are less significant.

3.9.8 Post-Northridge details
Prior to the Northridge earthquake, the special moment-resisting
frame (SMRF) with the pre-Northridge beam-to-column detail was
unchallenged with respect to its ability to perform as expected. This
confidence existed in spite of a fairly significant failure rate that had
been experienced when testing these connections in previous
research. For purposes of this section, the pre-Northridge detail is
considered to exhibit the following:
• CJP groove welds of the beam flanges to the column face, with weld
backing left in place and with weld tabs left in place
• No specific requirement for minimum notch toughness properties
in the weld deposit
• A bolted web connection with or without supplemental fillet welds
of the shear tab to the beam web
• Standard ASTM A36 steel for the beam, and ASTM 572 grade 50
for the column, for example, no specific limits on yield strength or
the F F ratio
y u
As a result of the Northridge earthquake and research performed
immediately thereafter, confidence in this detail has been severely
shaken. Whether this detail, or a variation thereof, will be suitable
for use in the future is unknown at the time of writing. More research
must be performed, but we can speculate that, with the possible
exception of small-sized members, some modification will be required
in order to gain the expected performance from structural systems
utilizing this detail.
As was previously stated, testing of this configuration had a fairly
high failure rate in pre-Northridge tests. Still, many successful results
were obtained. Further research will determine which variables are
the most significant in predicting performance success. Some changes,
however, have taken place in materials and design practice that

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