With constant code changes and the scramble
among manufacturers to make sure their
products comply with the newer codes,
there can be confusion in the specification
community as to which products are approved
for use in the field.
To help our customers better understand
these issues, it's important to first review the
product evaluation process and then discuss
some of the specific product lines that have
been affected by new code changes.
Product Evaluation Process
Products that are not specifically mentioned in
building codes must have some mechanism
for determining if the products comply with
the code. For example, the International
Building Code® (IBC) does not say "Use an
HUS26 to support the ends of joists," but it
does say "Connections depending on joist
hangers or framing anchors, ties and other
mechanical fastenings not otherwise covered
are permitted where approved. The vertical
load-bearing capacity, torsional moment
capacity and deflection characteristics of joist
hangers shall be determined in accordance
with Section 1715.1."
So in order to approve the hanger, a code
official would need to determine if it was
tested and evaluated as required in Section
1715. There are two ways code officials
can assess this; they can personally review
the manufacturer's testing and calculations
required by 1715.1, or they can rely on an
evaluation report published by a product
evaluation agency. Understandably, many code
officials choose to rely on evaluation reports.
To achieve an evaluation report, a manufacturer
must submit product information and
testing to evaluation agencies like ICC-ES and
IAPMO ES. These evaluation services evaluate
the building products based on Acceptance
Criteria. Products that meet the Acceptance
Criteria receive an evaluation report, stating
that the product either complies with the code
or is an alternate to what is specified in the
code. Engineers, specifiers and contractors
may rely on these reports to determine
whether to specify or purchase a particular
product while code officials use them to
verify approval.
As described above, in some cases the
approval criteria for a product is spelled out
in the code. For many other types of products
though, the code and its referenced standards
are not as specific as to how to evaluate a
product. In these cases, IBC Section 104.11
states that "An alternative material, design,
or method of construction shall be approved
where the building official finds that the
proposed design is satisfactory and complies
with the intent of the provisions of the code."
If the code does not specify how a product
is to be evaluated, then it's typically up to the
evaluation agency, working in conjunction
with manufacturers and interested parties, to
develop a specification on how to evaluate a
product, which is known as an Acceptance Criteria
or an Evaluation Criteria. The challenges
for evaluation agencies and manufacturers are
first to develop separate evaluation criteria for
each type of product and then to revise the
criteria whenever the applicable building code
changes or when other changes are merited.
Developing the Acceptance Criteria and then
providing documentation in accordance with
new requirements is a time intensive process
and helps explain why some products may
have evaluation reports for older codes,
but not for newer ones. In many cases, it's
not that the product does not comply with
the newer code, but more likely that the
Acceptance Criteria for the newer code has
not been developed; the manufacturer is in the
process of submitting their updated product
information to the evaluation agency; or the
agency has not yet completed their review of
the submitted information.
Two Simpson Strong-Tie® product lines
without specific evaluation criteria in the IBC,
include Steel Strong-Wall® prefabricated
shearwalls and Simpson Strong-Tie Anchor
Systems® post-installed adhesive anchors for
concrete. Changes in the IBC and in ICC-ES
Acceptance Criteria have affected the evaluation
reports for these products and therefore
should be discussed in more detail.
Anchors In Concrete
Our anchor systems products have been
affected by changes to referenced standards
in the IBC. The 2000 IBC contained new
provisions for the strength design of cast-in-place concrete anchors that became part
of ACI 318-02 Appendix D. Once ACI 318-02
was completed, it was referenced in the 2003
IBC for the design of concrete. For the first
time, that standard contained a mandatory
Appendix D that outlined design requirements
for both cast-in-place anchors (e.g. headed
studs, headed bolts, J-bolts and L-bolts), and
post-installed expansion and undercut anchors (excluding adhesive anchors, powder actuated fasteners and specialty inserts). While
these new requirements were significantly different and more rigorous than design
and analysis methods that had been used in the past, they also significantly reduced
the strength of concrete anchors compared with previous methodologies.
Along with ACI 318-02 Appendix D, the American Concrete Institute also published
a new test standard, ACI 355.2-01, Evaluating the Performance of Post Installed
Mechanical Anchors in Concrete. This test standard became the basis for the new ICC-ES
Acceptance Criteria AC193 for Mechanical Anchors in Concrete. In addition to AC193,
ICC-ES adopted a new Acceptance Criteria AC308 for Post-Installed Adhesive Anchors
in Concrete. These new Acceptance Criteria take into consideration the new provisions
of Appendix D. Since these new criteria covered strength design and concrete only, the
old ICC-ES Acceptance Criteria for adhesive anchors and mechanical anchors (AC58
and AC01, respectively) were revised so that they applied only to masonry elements.
Once the new Acceptance Criteria were published, ICC-ES revised manufacturers'
existing evaluation reports to remove recognition for post-installed anchors in concrete.
New evaluation reports for post-installed anchors in concrete require extensive testing
efforts using the new Acceptance Criteria. For example, tests now have to be performed
in cracked and uncracked concrete, in cleaned and partially cleaned holes, and in
dry and water saturated holes. Furthermore, anchors have to be creep tested at two
temperatures, tested in cracked concrete where the crack width is cycled and tested
in cracked concrete under a simulated seismic test. This is in addition to the many
embedment depths, spacing and edge distances, and load directions that must be
tested for each anchor size.
Simpson Strong-Tie is in the process of completing this laborious effort. Currently,
our Strong-Bolt® anchor carries a 2006 I-Code evaluation report for concrete that
is in compliance with AC193. Our Titen HD® anchor has been tested in accordance
with AC193, and a 2006 I-Code evaluation report for this anchor in concrete will be
available soon. Our two new adhesive anchor products, SET-XP™ Epoxy-Tie® Adhesive and the IXP™ Adhesive Anchor Insert, have been tested in accordance with AC308
and are expected to have an ICC-ES evaluation report by the end of the year. Check
www.simpsonanchors.com for the latest information about our anchor product line.
Prefabricated Shearwalls
Our Steel Strong-Wall® products also have been affected by the Acceptance Criteria
process. When first introduced, ICC-ES did not have an Acceptance Criteria for steel
prefabricated shearwall panels. In its current ICC-ES evaluation report (ESR-1679), this
product was evaluated under the 1997 Uniform Building Codes® and the 2000 I-Codes.
Over the past few years, ICC-ES along with industry (Simpson
Strong-Tie, other manufacturers, design engineers, academia,
associations, etc.) have developed new Acceptance Criteria for
this type of product, which resulted in the publishing of AC322 in
October of 2007 – Acceptance Criteria For Prefabricated, Cold-
Formed, Steel Lateral-Force-Resisting Vertical Assemblies. Part of
the criteria contained in the new AC322 for steel panels was carried
into the existing requirements for wood shear panels, AC130.
Working under the new AC322 and the revised AC130, which
took effect March 1, 2008 and November 1, 2007 respectively,
Simpson Strong-Tie is currently completing the testing and analysis
required to obtain an evaluation report for these products for the
2006 IBC and IRC. In the meantime, many building departments
have developed interim guidelines for acceptance of prefabricated
shearwall panels until 2006 IBC/IRC evaluation reports can be
obtained. Check with your local code official for their policy.
One other important item regarding ICC-ES Evaluation Reports is
the creation of a new report for Simpson Strong-Tie connectors,
ESR-2523. This is what's called an "Index Report." It does not
contain any technical information, but instead lists every stamped
(automated) and welded connector that has an ICC-ES evaluation
report and the respective report number. Connectors included in
ICC-ES Evaluation Reports will be identified by a label or stamp
containing this number, which provides an easy-to-use method for
building inspectors to verify approval.
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Reprinted from the Structural Report, Volume 5, Number 3, July 2008. Subscribe to the Structural Report, our free quarterly newsletter.
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