AISC 360 Specifications - Clarifying the Meaning of the Words OBSERVE and PERFORM

When the 2012 edition of the International Building Code (IBC) replaced the IBC 2009 code cycle, one of the significant changes was the deletion of Table 1704.3, “Required Verification and Inspection of Steel Construction.” Along with deleting this table, the terms periodic inspection and continuous inspection also disappeared from the IBC code vernacular regarding structural steel inspection. The IBC code stipulated that special inspections for structural steel be provided according to AISC 360.

AISC 360 introduced two words to determine the frequency of steel inspections: observe and perform. Note the exact AISC 360 definitions of these words in the narrative box at the bottom of this page. More than a decade ago, the words observe and perform mostly replaced the words periodic and continuous, respectively, and anxiety and confusion about their meaning still reign today.

Perform means that the special inspector will check and/or test every welded or bolted connection, including visually inspecting 100% of the welds and bolted connections. This 100% mandate is rooted in the American Welding Society (AWS) D1.1 welding code and the Research Council on Structural Connections (RCSC) code. What the word observe means for the metals special inspector is even more ambiguous because AISC 360 lists dozens of random-basis inspection tasks during construction phases. These tasks include observing the settings on the welding equipment; proper welding materials, preheats and interpass temperatures, and welding position; and other tasks regarding welds and bolted connections.

How much time does the special inspector spend on these random inspections, and how often do they visit the job site to do it? It is entirely up to the special inspector to decide the required time and magnitude of their inspections. AISC stipulates that “the inspector shall, at suitable intervals, observe joint preparation, assembly practice, welding techniques, and performance of each welder, welding operator, and tack welder to ensure that the applicable requirements of this code (AISC 360) is met.” Therefore the special inspector does whatever it takes to determine code compliance.

AISC 360 Chapter N, Section N5 (4)

(a) Observe (O); The inspector shall observe these items on a random basis

(b) Perform (P); These tasks shall be performed for each welded joint or member.

AISC Commentary Chapter N, Section 6.5.2 The inspector shall, at suitable intervals, observe joint preparation, assembly practice, the welding techniques, and performance of each welder, welding operator, and tack welder to ensure that the applicable requirements of this code are met.

For more information or further enthusiastic discourse on topics of CODE, please contact Alan Tuck at: atuck@fandr.com or 540.344.7939