Subject: Proposed Revisions to the Acceptance Criteria for Mechanical Anchors in Concrete Elements, Subject AC R1 (KS/ME).

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1 AC R1 #04 From: Philip Brazil Sent: Tuesday, January 20, :01 PM To: Monique Moody Subject: Response to AC R1 Subject: Proposed Revisions to the Acceptance Criteria for Mechanical Anchors in Concrete Elements, Subject AC R1 (KS/ME). I am writing in response to the letter from John Silva, dated November 17, 2008, and to ask the Evaluation Committee to reconsider its approach to specifying and referencing special inspection requirements in Acceptance Criteria such as AC193 and, ultimately, the evaluation reports that are issued based on them. I have been extensively involved in the development of the special inspection provisions of the IBC for several ICC code development cycles and am aware of the recent change approved by the ICC membership for special inspection of concrete anchors. I would like to draw your attention to Section of the 2006 IBC and compare it to Sections and of the 2003 IBC. Note that Items #2 and #3 of the 2006 IBC specify type and extent (emphasis mine) but Items #3 and #4 in both referenced sections of the 2003 IBC specify type and frequency (emphasis mine). These and many other changes were the result of approval by the membership of Proposal S76-04/05-AM, which was submitted by the Quality Assurance (QA) Subcommittee of the NCSEA Code Advisory Committee. There was another proposal developed independently of S76 for which I was the proponent: S77-04/05-WP. Both proposals including their committee actions are in the attached PDF, which I ask ICC-ES staff to please make available to the Evaluation Committee with this message along with a second attached PDF (see below). Note the length of the modifications to S76 approved by the Structural Code Committee (pages 1-2 of PDF). These were the result of extensive discussions between myself and members of the NCSEA QA Subcommittee after submittal of our separate proposals to ICC. We had not been aware of our separate efforts before the submittal deadline. The modifications were prepared by me with the goal of incorporating the changes proposed by S77 (pages 7-12 of PDF) into those proposed by S76 (pages 3-7 of PDF). The modifications were submitted to the Structural Code Committee as a floor modification and were approved by the Committee without further modification. The result of this effort was a composite proposal containing the best of Proposals S76 and S77. With approval of S76 as amended by the Committee, I withdrew S77. The key to our final agreement on the contents of the floor modification was in the changes highlighted above. In specifying frequency, the 2003 IBC was regulating the number of times a special inspector inspects. In specifying extent, the 2006 IBC regulates the degree to which a special inspector inspects. The distinction is critical to understanding what we accomplished in the 2004/2005 code development cycle and in enabling the administration and execution of the provisions of IBC Chapter 17 on special inspection. Chapter 17 did then and continues to specify a great deal of information on the required extent of special inspections and virtually nothing on its frequency. The frequency of special inspections is best left to the building official, the special inspectors and the design/construction team for the project. Chapter 17 can not and likely never will be developed in such a manner that the required frequency of special inspections is specified in a reliable manner. However, it can and should continue to specify the required extent of special inspections. And, in the code development cycles that followed the 2004/2005 cycle, numerous proposals were submitted to ICC and approved by the membership with that in mind. There is one detail, however, that was not adjusted for consistency with the change from frequency to extent: the definitions of periodic special inspection and continuous special 1 of 17

2 inspection, which refer to the frequency and extent of special inspection. In my view, continuous special inspection means an inspection that requires the special inspector to be present during construction and periodic special inspection means an inspection that the special inspector could accomplish after construction. There are two prominent examples. The first example is the inspection of high-strength bolts providing bearing-type or slip-critical connections. Bearing-type connections could be inspected after the bolts are installed but before they are concealed by finishes or other materials. Slip-critical bolts, however, must be inspected during installation at least because of the need to verify that the faying surfaces have been properly prepared. Table specifies periodic special inspection for bearing-type bolts and continuous special inspection for slip-critical bolts, which is an identification of extent, not frequency. Examples of identifying frequency would be the number of times a special inspector is required to visit the construction site to inspect and the percentage of bolts to be inspected but the IBC does not specify these aspects of special inspection nor does it intend to do so. The special inspection of single-pass and multi-pass fillet welds is similar to that of high-strength bolts. The second example is the inspection of reinforcing steel and concrete placement. Reinforcing steel can be inspected after its placement provided it is done before the concrete is placed. Concrete, however, must be inspected during placement at least because test cylinders need to be prepared to enable testing and verification of specified compressive strength. Table specifies periodic special inspection for reinforcing steel and continuous special inspection for concrete placement, also an identification of extent, not frequency. There are examples of identifying frequency similar to those noted above for high-strength bolts but the IBC also does not specify these aspects of special inspection. The evaluation reports issued by the ICC Evaluation Service frequently identify requirements for special inspection and should continue to do so. The reports also reference the requirements for special inspection in the IBC and should also continue to do so. The concern I have, and the purpose for this message, is to discourage distinguishing between requirements for periodic and continuous special inspection in the evaluation reports. The evaluation reports, especially those for post-installed concrete anchors, do an admirable job of specifying in detail what is required of a special inspector. Extent and frequency are often specified and I encourage this to continue. This level of detail, however, is not possible in the IBC, which relies almost entirely on the distinction between periodic special inspection and continuous special inspection for this purpose. Specifying detailed requirements for special inspection in an evaluation report should be seen as a substitute for the distinction between periodic and continuous special inspection in the IBC. Specifying both leads to confusion and detracts from an understanding of what is expected of special inspection by the building official, special inspectors and design/construction team. Because special inspections are specified in a detailed manner in some evaluation reports but are not specified in a similar manner in the IBC, other than to distinguish between periodic and continuous special inspection, the methods of specifying special inspections in evaluation reports and the IBC are incompatible and a clear distinction between them should be maintained. I have been utilizing ICC-ES, and before them ICBO-ES and NES, evaluation reports for over 30 years. During this time, I have taken great interest in what the reports have said about special inspection and have rarely, if ever, had difficulty in understanding the requirements and their relationship with those in the IBC until the proposal for which John Silva refers in his letter of November 17, 2008 was approved by the membership. In Table of the 2006 IBC (and 2000 and 2003 IBC), continuous special inspection is required for bolts installed in concrete prior to and during placement of concrete where allowable loads have been increased (emphasis mine). Because allowable stress design is not permitted by IBC Section for the design of anchors installed in hardened concrete or where load combinations include earthquake loads or effects (and other reasons), special inspection is not required for any bolts/anchors installed in concrete with rare exceptions (e.g., 2 of 17

3 Section ). Where special inspection is required for concrete construction but not for the bolts/anchors installed in the concrete prior to placement, verification of their installation is the responsibility of the building official who must be at the site after the bolts/anchors are placed but before the concrete is placed in order to accomplish their inspection. Given that there are also special inspectors present for the inspection of the reinforcing steel and concrete placement, there is the real possibility of no inspection of the bolts/anchors, which in my view is not acceptable. Proposal S117-07/08-AMPC (see attached PDF) changes Table to require (1) continuous special inspection of bolts installed in concrete prior to and during placement of concrete where allowable loads have been increased or strength design is used, and (2) periodic special inspection of anchors installed in hardened concrete. With respect to the bolts in Item (1), I strongly endorse periodic special inspection but continuous special inspection is not warranted. Bolts installed in concrete prior to and during placement of concrete can be inspected in the same manner as reinforcing steel. With respect to the anchors in Item (2), this requirement does not belong in the IBC and should be deleted. Post-installed anchors are not specifically permitted in the IBC but can be qualified for use through the alternate means and methods provisions of IBC Section and this has traditionally been done by anchor manufacturers through the ICC Evaluation Service. It is possible for a post-installed concrete anchor to be qualified for use through application of Appendix D of ACI 318 but there are none that I am aware of. It is not clear whether the anchors in Item (2) are intended to include those qualified for use by ICC-ES or other nationally recognized evaluation services but, given the requirement for periodic special inspection within the context of the IBC, there is the real possibility of post-installed anchors not being inspected until after they are installed, which in my view is not acceptable in most cases. If the membership chooses to place requirements in the IBC that are also in evaluation reports issued by ICC-ES, that is their prerogative. However, I would urge the Evaluation Committee to consider the impact that such overlapping provisions in the IBC and ICC-ES evaluation reports have. I recommend that where special inspection is specified in detail, such as with post-installed concrete anchors, whether such inspection is periodic or continuous not be stated. The detailed description of the inspection requirements will suffice. Sincerely, Philip Brazil, P.E., S.E. Senior Engineer Reid Middleton th Street SW, Suite 200 Everett, WA (425) (main) (425) (fax) (425) (direct) Engineers Planners Surveyors 3 of 17

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