ACI 440 Main Minutes S12 - American Concrete Institute

Minutes

ACI Committee 440-FRP Reinforcement

Main Committee Meeting Tuesday, March 20, 2012 – 8:06 am – 11:02 am

Hyatt Regency– Dallas, TX Reunion FH

Chairman: Dr. Carol K. Shield Secretary: Mr. William J. Gold

Attendees: Voting Members (30)ALKHRDAJI, TAREK BAKIS, CHARLES BELARBI, ABDELDJELIL BISBY, LUKE BLASZAK, GREGG BRADBERRY, TIMOTHY BROWN, GORDON BROWN, VICKI BUSEL, JOHN FALLIS, GARTH

GOLD, WILLIAM GREEN, MARK GREMEL, DOUG GROSS, SHAWN HARIK, ISSAM LEE, MICHAEL LOPEZ DE MURPHY, MARIA MYERS, JOHN NANNI, ANTONIO OKEIL, AYMAN

OSPINA, CARLOS RASHEED, HAYDER RIZKALLA, SAMI SEN, RAJAN SERACINO, RUDOLF SHIELD, CAROL SILVA, PEDRO STEERE, SAM THOMAS, JAY WITT, SARAH

Non-Voting Consultant Members (1)BURGOYNE, C J

Non-Voting Associate Members (22)ABD EL FATTAH, AHMED BAE, SANG-WOOK CARLONI, CHRISTIAN CHENG, DAWN CHOI, OAN CHUL DESCHAMPS, DOMINIQUE EKENEL, MAHMUT EL-SALAKAWY, EHAB

GALATI, NESTORE GARNER, ANDRE GUNDBERG, TREVOR KANTIKAR, RAVINDRA KIM, YAIL JIMMY KLEINHAUS, DANIELLE LARSON, PETER MATTA, FABIO

MCCLASKEY, CHARLES ORTON, SARAH QUAGLIATA, MARIO RABINOVITCH, ODED SESHAPPA, VENKATESH STRATMAN, BRIAN

Visitors (8) ERICSON, ALVIN FISCHER, JON LEWIS, CHRIS MARTIN-PFLEGER, KATHY MIDDLESWORTH, JEFF MONTEMAYOR, TOMAS REDDY, D V SAMBLANET, PHILLIP

1. Dr. Shield called the meeting to order at 8:06am 2. The attendees made self-introductions 3. Dr. Shield proposed to modify the agenda to omit the 440-D subcommittee report since the co-chairs

were not present at this meeting and to move the 440-L subcommittee report to the beginning of Agenda item #8, 440 Activities Overview, in order to accommodate schedules. Dr. Shield then invited a motion to approve the revised agenda. Mr. Blaszak moved to approve the agenda. Mr. Busel seconded the motion. The motion carried.

4. Dr. Shield invited a motion to approve the minutes from the previous meeting in Cincinnati. Dr.

Belarbi moved to approve the minutes. Dr. Seracino seconded the motion. Dr. Bakis indicated that there was one date wrong on the 440-K report. The date of publication of the ASTM D 7565 standard should be 2010, not 2009. Dr. Shield indicated that the minutes would be revised to correct this. The motion was put to a vote. The motion carried.

5. Chairman’s report – Dr. Shield began her report with news from TAC. She indicated that the

Technical Committee Manual now includes provisions for allowing Technical Committees to produce videos. Committee voting is done on storyboards that serve as the basis for the videos. She also reported that the rules around membership in subcommittees have now been modified such that the only type of membership on subcommittees is voting member (there are no longer associate member or consulting member levels on subcommittees). Dr. Gross inquired whether one needs to be a member of the Main committee to be a voting member on a subcommittee. Dr. Shield indicated that one would not, however it is recommended. Dr. Shield indicated that committees are being asked to compare definitions in their documents to the CT (Concrete Terminology) document before sending documents to TAC. This is part of an effort to maintain consistency between the CT and committee documents. Committees are being asked not to repeat definitions in committee documents that already exist in the CT unless absolutely necessary.

Dr. Shield announced that Dr. Trey Hamilton will be stepping down as Chair of the 440-L subcommittee and that Dr. Jennifer Tanner would be taking over as Chair of the subcommittee. The committee applauded the work of Dr. Hamilton. Dr. Shield also expressed congratulations to 440 Committee members who were recently named Fellows of ACI. Those included Dr. Shawn Gross, Dr. Maria Lopez de Murphy, and Dr. James Hanson. ACI 440 Committee member Mr. Doug Gremel also had a feature cover article in the February 2012 Concrete International on the Miami Metrorail project. There are two sessions related to FRP at this convention in Dallas. These are Parts I and II of “A Fracture Approach for FRP-Concrete Structures”. These sessions are being co-sponsored with Committee 446 and are being organized by Dr. Maria Lopez de Murphy and Dr. Christian Carloni. There are a total of 11 presentations and ACI is publishing an SP of the papers being presented. Dr. Lopez de Murphy indicated that the SP had already been through review and should be available soon. In upcoming ACI conventions, Dr. Shield reported that there is a session planned for the Spring 2013 convention in Minneapolis. This session is being co-sponsored by Committee 345 and is titled “Advanced Materials and Sensors towards Smart Concrete Bridges: Concept, Performance, Evaluation, and Repair”. Abstracts should be sent to Dr. Jimmy Kim ([email protected]) by July 15, 2012.

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Dr. Shield reminded the committee that we have standardized the meeting schedule for Committee 440 and its subcommittees. She encouraged all subcommittees to remain active throughout the year even if they only meet once per year.

Dr. Shield informed the committee of upcoming conferences:

11th World Pultrusion Conference March 22-23, 2012, Istanbul, Turkey www.pultruders.com

SAMPE 2012 May 21-24, 2012, Baltimore, MD www.sampe.org

ACMBS VI (6th International Conference on Advanced Composite Materials in Bridges and Structures)

May 22-25, 2012, Kingston, Ontario Abstracts due May 31, 2011 – [email protected] Contact Mark Green [email protected] www.acmbs2012.ca

CICE 2012 (6th International Conference on FRP Composites in Civil Engineering) June 13-15, Rome, Italy www.cice2012.it

Green Composites Workshop – Recycling Composites June 21, 2013 Chicago www.acmanet.org

ICCE-20 (20th International Conference on Composites/Nano Engineering) July 22-28, 2012, Beijing, China www.icce-nano.org

SAMPE TECH 2012 October 22-25, 2012, Charleston, SC www.sampe.org

COMPOSITES 2012 Feb. 21-23, 2012, Las Vegas, NV, www.ACMAshow.org

Dr. Shield presented an overview of the status of committee documents:

The guideline provisions for the use of FRP for blast upgrades are now under ACI Committee 370. A ballot on the document by Committee 370 is planned prior to the Fall 2012 ACI Convention. Committee 440 will then have a chance to ballot the document prior to the document being submitted to TAC for review.

The 440.1R will be sent to TAC for review by April 10, 2012. Updates to 440.2R will be discussed later in this meeting The 440.3R document has been returned to ACI staff and it is anticipated that this will be

published this spring. Dr. Shield began a discussion on coordination with ACI Committees 562 and 563. She explained that Committee 562 is currently writing a concrete repair code (similar to ACI 318) and Committee 563 is

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writing a repair construction specification (similar to ACI 301). The intention of Committee 562 is to reference other mandatory language documents. In order to facilitate reference to FRP strengthening systems in ACI 562, Committee 440 needs to first develop a mandatory language material specification for FRP strengthening systems and will eventually need to develop a mandatory language design specification (ACI 562 will currently direct readers to the non-mandatory language 440.2R document, but only in the commentary). The intention of Committee 563 is to either reference mandatory language documents or include specifications directly. Committee 440 will need to produce construction specification language to facilitate the inclusion of FRP systems in the 563 document. Dr. Shield indicated that we have a narrow window of opportunity to have the materials specification for FRP strengthening systems completed and into the ACI 562 document. ACI 562 is aiming to be accepted into the next IEBC code (to be proposed at the May 2013 IEBC meeting). In order for the FRP materials specification to be included in this cycle, this specification must be balloted with negatives resolved and sent to TAC for review by the middle of April 2012. If we miss this deadline, the FRP materials specification will not be included until the next IEBC cycle in 2016. To this end, we will be issuing a ballot on Monday, March 26, 2012 with a short 7-day canvassing period. Negatives on the ballot will be resolved via a virtual (web-based) meeting in early April. Mr. Blaszak asked whether other “feeder” committees were under the same tight schedule. Dr. Shield indicated that the other referenced committee documents are already finished. Mr. Busel asked whether Dr. Shield would be sending out an e-mail to voting members alerting them of these plans. Dr. Shield indicated that she would be and that she would also be sending out an e-mail to schedule a meeting time to resolve negatives. For the ACI 563 document (construction specification for repair materials), Dr. Shield indicated that we have two options: 1) Committee 440 develops a construction specification that ACI 563 references, or 2) Committee 440 drafts language that Committee 563 includes directly in the ACI 563 document. She indicated that with option (1), we maintain control of the document, but with option (2) FRP materials become a larger part of the mainstream with other repair techniques. She indicated that her preference would be option (2). She also indicated that the current plan is to have ACI 563 follow the publication of ACI 562 by one year. Dr. Shield then presented the status of other Committee documents as follows:

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6. 440 Membership Overview – In Dr. Shield’s membership report, she reported that, sadly, ACI Committee 440 member Mr. Jim Speakman recently passed away. She also indicated that the voting membership of Committee 440 continues to be evaluated. Dr. Shield reminded all associate members that the best ways to be considered for voting member status are to attend committee meetings, vote on documents that are balloted (even as an associate member), and become involved in subcommittee work and task groups. The current breakdown of committee membership and breakdown as of the Spring 2012 is shown below:

7. Ballot Results for 440.2R – Mr. Lee reported on the results of the ballot involving new seismic

design recommendations to be included in the next revision of the ACI 440.2R document. The ballot included three items: 1) a new Chapter 13 with seismic recommendations, 2) example problems based on these recommendations, and 3) a new appendix with additional detail on these recommendations. As a result of the ballot, 24 negatives were tallied. Ten of those negatives are related to item (1), nine related to item (2), and five related to item (3). A discussion of the negative comments was held at the 440-F subcommittee meeting. Based on the discussions, seven negative comments were withdrawn or changed to AC. These comments are noted below: Comment

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N1-02 Fallis 2 5 N “Comprehensive investigation … a structure or its elements” not part of the scope this document

Withdrawn

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N1-05 Fallis 8 19 N How is “k” calculated Changed to AC N1-11 Myers 10 2 N If Cf is ignored in the model are there any

concerns if the shear wall is cycled under seismic load that the bond will suffer as the compression region is cycled to resist forces in tension as a Tf component? Perhaps a non-issue at certain drift ratios, but still a question related to bond degradation that I would like to ask. If the answer is that research has not shown any concerns, I will withdraw this negative.

Changed to AC

N1-12 Myers 12 4 N Why is a 0.85 factor used? Has there been calibration based upon different potential failure modes (i.e. FRP rupture, debonding, etc.)? What is the basis for using 0.85? It is not clear.

Withdrawn

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N1-14 Ospina N The efforts of 440F for putting together this new Chapter in ACI 440.2R are appreciated. However, I believe the document could be improved substantially if the following aspects are addressed: First, the seismic strengthening design philosophy of RC structures varies depending of the type of structure being strengthened. Seismic design of RC frame-type buildings is traditionally based on the “strong column-weak beam” concept whereas seismic design of RC bridges and pile-supported piers and wharves follows the “weak column-strong beam” approach. The corresponding strengthening philosophy is to revolve around these concepts too, and sometimes could even drift away depending on the selected seismic performance level targeted for the upgraded structure. Differentiation between the two approaches has significant implications on the applicability of FRP because the strengthening design procedures with FRP may vary. Axial load levels, ductility demands, overstrength factors, and capacity concept principles, among other factors, may dictate different requirements, challenges (and shortcomings) for the intended FRP solution. The proposed Chapter certainly provides designers with tools to handle a wide variety of strength and ductility checks but it lacks substance at the concept level as to what the fundamental design philosophy, strengthening approach, goals and performance objectives should be depending on the RC structure under consideration. Unless the scope is to deal with RC buildings only, the Chapter also needs to provide designers with a clear direction as to how FRP can be used to strengthen RC bridges and pile-supported marine structures such as wharves and piers. These are huge markets for FRP use. How much overlapping there needs to be between ACI 440.2R and ASCE/SEI 41 is something the main committee needs to discuss. From a designer viewpoint, I would like to see explicit guidance from ACI 440.2R to fully understand what FRP can do when conceived as part of a strengthening/rehabilitation solution for different types of RC structures. For the sake of fairness, existing FRP strengthening standards in other countries do not handle this issue well. This is an opportunity for us to stand out. Secondly, I am convinced there is a need to remark firmly, up front, that seismic strengthening of RC structures with FRP is to follow Capacity Design principles. The goal of Capacity Design is to identify flexural yielding regions in the structure, design those regions for specified moment strengths, and then calculate design shears based on the assumption that the flexural yielding regions will develop probable moment strengths (which will likely exceed the specified values). Hence, the Chapter should contain explicit language dictating that the addition of FRP as part of a strengthening or rehabilitation solution shall not trigger a premature brittle shear failure either in the elements being strengthened or anywhere else. Enough info is given on how plastic hinge zones need to be strengthened to enhance their ductility and strength but little language is provided to remark how undesirable it is for a brittle shear failure to develop prior to the plastic hinge developing its full capacity. Explicit guidance is needed to check the shear capacity of FRP-strengthened beams, columns and beam/columns, and the shortcomings or drawbacks of the proposed equations clearly listed, to make sure Capacity Design concepts are fully complied with. Finally, I believe the proposed Chapter has concentrated on the strengthening at local element level with little attention to the effect of FRP strengthening on the overall seismic response of the structure. Whether the FRP strengthening is to be designed using force-based (typical of RC buildings and, very often, bridges) or displacement-based (typical of pile-supported RC marine structures such as piers and wharves, and sometimes bridges (depending on the code or local DOT requirements), there is no guidance as to what the resulting R or m factors will be when strengthening RC structures with FRP. I ignore if this important aspect of the strengthening design process is to become part of future revisions of ASCE/SEI 41. All I am trying to say is it would not hurt for ACI 440.2R to touch base on these key design aspects. If the subcommittee feels there is little information and they do not want to overcommit then please say so and list those areas where more research is needed.

Withdrawn

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N1-43 Shield 12 15 N I disagree with the statement “anchorage of FRP is considered good practice” It isn’t good practice, it is required for the FRP to work, in many cases, the FRP is anchored just with the adhesive. I think what is meant here is that “enhanced anchorage” or maybe “mechanical anchorage” please change the wording.

Changed to AC

N1-45 Shield 12 22-23

N Need to add clarification on the term “length of section in the direction of the shear considered”

Changed to AC

Dr. Ospina indicated that his negative was withdrawn because he realizes that this is not a standalone document. He indicated that his negative was from a designer’s perspective and that the design philosophy for bridges versus buildings can be different. He indicated that he wanted to avoid having the document just mention that wrapping of columns, for example, can be done without looking at other structural effects. He is fine with having the document point the reader to other design documents that cover these issues (e.g., ASCE/SEI 41). Mr. Lee indicated that the scope of this document was intentionally limited to not deal with seismic philosophy. Dr. Silva indicated that the document does make mention of these philosophical issues, but then directs the reader to the appropriate reference documents. Dr. Shield indicated that we should more directly link the seismic document to the reference documents. Dr. Ospina indicated that the reference documents do not take into account FRP. Dr. Silva indicated that ASCE 41 provides this information based on response, not on materials. Dr. Shield indicated that we should indicate specifically how the documents are linked, for example where and how the factors from ASCE 41 should be used with FRP retrofitted sections. Ms. Witt indicated that this may be difficult because the factors cannot be applied to every case. Dr. Ospina agreed and indicated that we should just state that we do not offer guidance on specific factors to use. Dr. Shield indicated that this comment needs to be removed from the items to be withdrawn and we need to have vote on this item. Mr. Lee agreed and indicated that we should also discuss the other points of Dr. Ospina’s negative. Dr. Ospina indicated that we need to have a statement indicating that the designer should follow capacity design principals. Mr. Lee indicated that there are instances where the document is emphasizing recommendations that follow these principals, but that the document does not specifically state that capacity design principals be followed. Mr. Lee indicated that the third part of the negative was outside of the scope of the document. Dr. Ospina indicated that this is really tied to the first part of his negative. Mr. Kantikar indicated that the intent of the document was to address local members only. Motion: Mr. Lee moved to add a sentence into the scope of the document that indicates that this document should be used in conjunction with ASCE 41 and ACI 369. Dr. Ospina seconded. Dr. Shield then invited discussion on the motion. Ms. Witt asked whether we should add other reference documents. Dr. Silva and Dr. Shield indicated that we are referencing ASCE 41 throughout the document and that we should keep only this reference. Upon hearing the motion, the motion was put to a vote. 22 members voted “affirmative”, 0 members voted “no”, and 1 member abstained (Witt). The motion carries. Dr. Shield indicated that the second part of Dr. Ospina’s negative will need to be dealt with later as part of a web ballot.

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Mr. Lee then proceeded to present a series of motions to the committee to resolve the additional negatives on the ballot. He indicated that the first motion was to address negative comments related to organization and technical language. Motion #1: Mr. Lee moved to find the following negatives persuasive and resolve these negatives as indicated in the table below. Comment

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N1-01 Fallis N Entire document reads disjointed and in places difficult to follow. Made suggestions where I can but there are places that are just too difficult to do in isolation. I recommend an editorial group work to clean it up.

Agree. Editorial group to be led by Mark Green will work to improve overall readability of document. Work of EG will commence after technical negatives have been resolved.

N1-15 Ospina 1 25-29 N I think you need to reorganize some of the references listed. The use of the term “seismic rehabilitation of concrete structures” in this paragraph may lead to some confusion. Are you talking about testing of full-scale RC structures strengthened with FRP? Some of the references listed refer to research of local elements, such as beam/column joints (e.g. Ghobarah and Said (2002). Shouldn’t this be listed in the next paragraph instead?

Agree. Will review organization of references and clarify as appropriate.

N1-17 Ospina 1 36-39 N This paragraph is not reading well. Consider relocating the 2nd and 3rd sentences over to Page 2, Paragraph 1, after reporting that the guidelines are not meant to address residual strength of the structure and the FRP retrofit system

Agree. Will make suggested changes.

N1-20 Ospina 4 12 N Replace “position of the neutral axis” with “neutral axis depth”.

Agree. Will revise as suggested.

N1-21 Ospina 8 6 N Revise to read “…the probable flexural strength, Mpr, that can be generated…”


N1-24 Ospina 12 10 N Please add units in Eq. 13-22 Will add following: fc=psi, d=inches, tw=inches, and Vn=lbs

N1-30 Parretti 11 8 N Add “Two possible” before “Conceptual methods for anchorage of….”


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N1-31 Parretti 11 9 N Change: “Any anchorage method must be properly….” To: “Any anchorage method, included the method presented in Figure 13-4, must be properly….”


N1-33 Parretti 12 26 N “Clear” spacing? Please clarify. Will revised to “center-to-center spacing.”

N1-35 Shield N Throughout the document, it is imperative that we indicate the direction of fiber, it is not given anywhere in the figures or text.

Agree. Will indicate fiber direction by adding closely spaced parallel lines.

N1-36 Shield 4 4 N Change “beam” to either “flexural member” or “beam or column” Clearly what is in the figure is NOT a beam

Will clarify text.

N1-37 Shield 4 5 N Need to indicate the direction of fiber in the figure.

See Item N1-35

N1-38 Shield 4 23 N The sentence is incorrect. In addition to rectangular sections with h/b<1.5, you can also use 13-5 for circular sections (and I imagine elliptical sections). Change sentence as follows: …Eq. (13-5) is not valid only for rectangular sections with an aspect ratio h/b <= >1.5.”


N1-39 Shield 7 6 N This sentence as written makes no sense – the wrap can’t be more or less than the requirements, what is about the wrap that you need to meet the requirements – the area? The length?

Agree. Change “… the FRP wrap …” to “… the area of the FRP wrap …”

N1-44 Shield 12 21 N Eq. 13-23 is not an equation, it is a term. Please turn it into an equation.

Agree. Delete equation and incorporate it into text by replacing Lines 19-24 with following: “FPR should be provided on two faces of the wall if Vu exceeds , where Acv is the gross area of concrete section (in units of in2) bounded by web thickness and length of wall in direction of shear force, and fc is in units of psi. The intent of this provision is to inhibit fragmentation of concrete in the event of severe cracking during a severe seismic event.”

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Motion #1 was seconded by Mr. Fallis. Dr. Shield opened the floor for discussion on the motion; there was no discussion. Upon hearing the motion, the motion was put to a vote. 25 members voted “affirmative”, 0 members voted “no”, and 0 members abstained. The motion carries. --------- Mr. Lee then described the list of negatives in the table below that relate to various technical items. Motion #2: Mr. Lee moved to find the following negatives persuasive and resolve these negatives as indicated in the table below. Comment

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N1-04 Fallis 8 9 N Replace “it is recommended” is it yes or is it no?

Delete “it is recommended” (two places in paragraph) and provide stronger language.

N1-06 Fallis 9 18 N What is “enhanced probable flexural strength” and how does it relate here – unclear - explain

Agree. New Line 17-18 sentence: “The shear strength of walls retrofitted for flexure should be evaluated and compared to the shear corresponding to the probable flexural strength of the retrofitted structure.”

N1-07 Gross 5 5 N Change Eq. 13.7 to Eq. 13-6 Agree. N1-08 Myers 1 20 N Modify text from “…lead to

changes…” to “…lead to significant changes…”. Rational: There certainly is some minor change in stiffness depending on the # of plys/strengthening and in addition what I call “apparent stiffness” if any cracks exist (i.e. restriction of existing crack opening).

Agree. New Lines 20-21: “FRP strengthening does not lead to a change in the stiffness or mass that needs to be accounted for in design. As a result, a reevaluation of the seismic demand after FRP strengthening is typically not required.”

N1-16 Ospina 1 34 N Please provide the references associated with the “findings” you report

Change Line 34-35 as follows: “In addition, several installations of FRP strengthened members are known to have experienced seismic events. Failure of these members has not been reported.”

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N1-22 Ospina 8 19 N How do you calculate k? Do we need a figure or an equation?

Clarify source of k by changing Lines 18-20 as follows: “where f is the reduction factor applied to the contribution of the FRP system in accordance with Chapter 11, and k is a reduction factor specified in ASCE/SEI 41 (2007) that depends on the displacement ductility of the section, d, (Sezen and Moehle 2004).”

N1-23 Ospina 12 8 N Eq. 13-21 shows b. Text calls for g. Which one is correct?

Correct term is g.

N1-25 Parretti 5 5 N In Eq. 13-6, define what fs is and how it is calculated.

Change sentence in Line 4-5 to read as follows: “Therefore, regardless of FRP retrofit, the stress in the longitudinal reinforcing bar fs should not exceed the … ”

N1-36 Shield 4 4 N Change “beam” to either “flexural member” or “beam or column.” Clearly what is in the figure is NOT a beam.

Agree. Replace text beginning on Page 3, Line 31 and ending on Page 4 Line 4 with following: “In FRP jacketed beams, the plastic hinge length, Lp, can be approximated using the procedure by Mattock (1950) as twice the beam height (2h). In FRP jacketed columns, the plastic hinge length, Lp, can be computed using Eq. (13-3) (Priestley et al. 1996). 13-3 Where dbl and fy are, respectively, the diameter and yield stress of the longitudinal steel, and g is the clear gap between the FRP jacket and adjacent members, as shown in Figure 13-1. The gap g should be no greater than 2 in. (50.8 mm).”

N1-42 Shield 12 7 N What is b in Eq. 13-21, need to define this or fix the subscript

See Item N1-23

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Motion #2 was seconded by Mrs. Witt. Dr. Shield opened the floor for discussion on the motion; there was no discussion. Upon hearing the motion, the motion was put to a vote. 27 members voted “affirmative”, 0 members voted “no”, and 0 members abstained. The motion carries. --------- Mr. Lee then described the list of negatives in the table below pertaining to recommendations on beam-column joints. Motion #3: Mr. Lee moved to find the following negatives persuasive and resolve these negatives as indicated in the table below. Comment

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N1-09 Myers 9 4 N We should not say “…FRP systems could be one of the most effective solutions…” As written the statement lends doubt. It should be re-written to be decisive in one fashion or another. i.e. “are one of the most effective”

Each negative deals with beam-column joint discussion on Page 9, Line 3-9. Replace with: “Experimental evidence (Pantelides et al. 2008, Silva et al. 2007, Pampanin et al. 2006, Bracci et al. 1992b 1992c) has shown that FRP systems can be an effective solution for increasing the shear and energy dissipation capacity of unconfined joints. Experimental evidence (Pantelides et al. 2008, Silva et al. 2007) has also shown that the FRP used to confine the joints must be properly anchored to be effective. The cited references include information that can provide guidance in determining if an FRP system can be a viable option for enhancing the performance of unconfined joints.”

N1-10 Myers 9 6-7 N The document should provide the details or reference the anchorage details being discussed so the reader has a clear picture of what is being discussed with tolerances.

N1-40 Shield 9 5-6 N I have no idea what this sentence is trying to say, particularly the part that says “providing them with increased tensile strength” I don’t think of joints as having tensile strength, so what really are we doing here?

Motion #3 was seconded by Mrs. Witt. Dr. Shield opened the floor for discussion on the motion; there was no discussion. Upon hearing the motion, the motion was put to a vote. 23 members voted “affirmative”, 0 members voted “no”, and 0 members abstained. The motion carries. --------- Mr. Lee then described the negatives listed in the table below pertaining to cutting slots in an existing structure to allow for continuous placement of FRP reinforcement. Mr. Bradberry asked whether it

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would be appropriate to reference testing on the anchorages. Mr. Lee indicated that this would be more appropriate for the detailing section of the document. Dr. Seracino asked whether the language on the first part of the table on discontinuous be incorporated into the first part. Dr. Burgoyne indicated that there is some upcoming work on fracture mechanics that will help illustrate when additional anchorage is used. He does not think that a blanket statement that it is needed in every case will be necessary. Dr. Shield pointed out that the language only indicates that the transverse wraps may be used; it does not indicate that they have to be used.

Motion #4: Mr. Lee moved to find the following negatives persuasive and resolve these negatives as indicated in the table below.

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N1-03 Fallis 7 1 N “localized cutting of the slab …” What will this do to the structure?

Replace text beginning at Page 6, Line 29 and ending at Page 7, Line 2 with

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N1-27 Parretti 7 1 N Complete wrapping of FRP flexural reinforcement is impractical for beams due to presence of the flooring system. Such recommendation, if adopted, could prevent the use of composites. In place of complete wrapping, the Committee could suggest the use of anchors to prevent FRP delamination, as it was done elsewhere in the document.

following: “Within plastic hinge regions of beams, it is recommended that the flexural FRP reinforcement be wrapped by transverse FRP that wraps completely around the perimeter of the section. Such wrapping provides higher resistance against debonding of the flexural FRP reinforcement under cyclic loading. If the beam is part of a floor system, the wrapping may be achieved by localized cutting or coring of the slab, provided that such modifications do not adversely impact the performance of affected elements. In instances where flexural FRP reinforcement is installed only along the beam soffit, the transverse FRP may not need to wrap completely around the section. In these instances, supplemental anchorage may also be used in conjunction with transverse FRP wrapping to provide sufficient resistance against debonding of the flexural FRP reinforcement.”

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N1-29 Parretti 8 26 N A similar comment as given on Pg 7 Ln 1 applies here as well.

Replace text at Page 8, Lines 26-27 with following: “In order to account for cyclic load effects, the FRP shear strengthening should wrap completely around the perimeter of the section. In cases where the FRP shear strengthening cannot be completely wrapped around the section, Supplemental anchorage may be used in conjunction with discontinuous FRP wraps only when justified by a detailed engineering analysis, project-specific testing, or relevant experimental evidence in cases where the FRP shear strengthening cannot be wrapped completely around the section.

Motion #4 was seconded by Mrs. Witt. Dr. Shield opened the floor for discussion on the motion; there was no discussion. Upon hearing the motion, the motion was put to a vote. 26 members voted “affirmative”, 0 members voted “no”, and 0 members abstained. The motion carries. --------- Mr. Lee then described the negatives listed in the table below pertaining to the use of wall height or wall width when computing capacity that FRP provides to a shear wall. Dr. Okeil indicated that his comment was addressed with a slight difference in that the 0.80 factor is not applied when the height is used – only when the width is used. He indicated he agrees with this resolution. Motion #5: Mr. Lee moved to find the following negatives persuasive and resolve these negatives as indicated in the table below.

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N1-13 Okeil 12 3-7 N Referencing Eq. 11-3 for shear strength calculations in FRP repaired walls may be inappropriate. We went through this with the masonry guide and ended up defining an effective masonry depth equal to the min(height, depth) in Eq. 10-5 of 440.7R-10. A similar approach should apply here. If we have a wall with Hw<Lw, a 45-deg crack will cross a smaller number of strips (≈ 0.8 Hw / sf) than the equation implies (dvf / sf = 0.8 Lw / sf ) as shown below:

Suggest defining dvf as follows: dvf = min(0.8Hw, 0.8Lw)

Agree. Instead of stating that Vf is the contribution of the FRP system to shear strength given by Eq. (11-3), revise to state that Vf = Afv ffe (dfv /sf) where dfv is the smaller of Hw or 0.8Lw

Motion #5 was seconded by Mrs. Witt. Dr. Shield opened the floor for discussion on the motion; there was no discussion. Upon hearing the motion, the motion was put to a vote. 26 members voted “affirmative”, 0 members voted “no”, and 0 members abstained. The motion carries. --------- Mr. Lee indicated that the sixth motion is related to Figure 13-2. He indicated that an appropriate reference would be included as part of the resolution. Dr. Orton indicated that one of her papers would be appropriate and could be added as a reference. She will provide the reference to Mr. Lee. Motion #6: Mr. Lee moved to find the following negatives persuasive and resolve these negatives as indicated in the table below.

d

H

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Comment

# Reviewer Page

# Line


N1-28 Parretti 7 17 N In Fig. 13-2, drawing is unclear. Please provide plan view as well.

Replace sentences in Page 7, Lines 13-16 with following: “A conceptual FRP development detail is depicted in Figure 13-2. Additional details of FRP development and anchorage at ends of retrofitted members can be found in (INSERT REFERENCES BY ORTON ETC.). Any anchorage method must be properly evaluated before it is selected for field use. Such an evaluation should consider FRP strain limits, FRP debonding, and supplementary anchorage requirements.”

N1-34 Rasheed 7 17 N Fig. 13-2 is showing the longitudinal FRP to cross the beam-column joint. This is physically impossible. Either change figure or provide guidance on how the longitudinal FRP continuity is preserved.

N1-41 Shield 11 9 N Need to tell the reader exactly what needs to be considered to “properly evaluate” the anchorage method. (like what was done on page 7 lines 15-16)

Insert after Page 11, Line 10: “Such an evaluation should consider FRP strain limits, FRP debonding, and supplementary anchorage requirements.”

Motion #6 was seconded by Mrs. Witt. Dr. Shield opened the floor for discussion on the motion; there was no discussion. Upon hearing the motion, the motion was put to a vote. 25 members voted “affirmative”, 0 members voted “no”, and 0 members abstained. The motion carries. --------- Mr. Lee indicated that the last motion is related to the comments and resolution in the table below. It is being proposed to find these comments non-persuasive. Mr. Ospina indicated that he agrees with the resolution on his two negatives listed and withdrew these negatives. Motion #7: Mr. Lee moved to find the two remaining negatives in the table below non-persuasive.

Comment

# Reviewer Page

# Line


N1-18 Ospina 3 10 N Please elaborate on why jacketing under the listed conditions is not recommended.

Listed conditions are based on available research and were adopted in previous ballots. WITHDRAWN

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Comment #

Reviewer Page #

Line #


N1-19 Ospina 4 4 N Is the invoked Lp definition valid regardless of the type of beam cross-section? Is it applicable for T-beams? How about beams with a different cross-section? What are the assumptions and limitations behind Mattock’s plastic hinge length definition? How about looking for additional references published after 1959 on the subject of plastic hinge length in beams?

Balloted definition represents consensus of 440F. In addition, definition is consistent with distance prescribed in ACI 318. WITHDRAWN

N1-26 Parretti 5 18 N In Eq. 13-9, provide an equation for l .

Definition is provided in text. Computation is straightforward.

N1-32 Parretti 12 22 N Provide a better definition of Acv and possibly an equation for it.

Definition and terminology taken from ACI 318.

Motion #7 was seconded by Mrs. Witt. Upon hearing the motion, Dr. Shield indicated that she wanted to make sure the committee was aware that we are finding these comments non-persuasive even though Mr. Parretti is not here to discuss them. Dr. Shield opened the floor for discussion on the motion; there was no discussion.. The motion was then put to a vote. 27 members voted “affirmative”, 0 members voted “no”, and 0 members abstained. The motion carries. --------- Mr. Lee indicated that once the document revisions were complete, a new ballot on the examples and appendices would be put forth to the committee. Dr. Shield indicated that the committee is looking forward to this ballot.

8. 440 Activities Overview

440-L – Dr. Meyers reported on the activities of the 440-L subcommittee. He indicated that based on the previous ballot on the durability document, the document is being revised and reorganized. He presented the new table of contents (attached to these minutes as Appendix A) and explained that the intent was to scale Chapter 3 down significantly. This is in line with the original intent of setting guidelines for gathering consistent data for collection into a database. The reorganized document discussed at the subcommittee meeting was well received. The subcommittee will now work on incorporating comments from the last ballot and hopes to ballot the document again this summer. Dr. Shield emphasized that the voting members need to keep in mind that we agreed to a specific scope and format at the last convention in Cincinnati. 440-Task Group on Materials Specification for Externally Bonded FRP – Dr. Shield reported on the efforts of the Task Group. She indicated that a new material specification would be sent out for main committee ballot next week. There will be an additional document that will be circulated with the ballot that explains the scope of the document (what is covered, what is not, what will be left to include later in a construction specification). She reported that one of the major issues that had to be overcome was how to deal with the material properties minimum values. She indicated that the

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durability tests follow ICC-ES AC 125 and that a construction specification will follow and will cover issues around bond and bond testing. Moving forward we will need to further define requirements for Tg. We will also add NSM, laminates, and multi-directional fabrics in future revisions. 440-H – Dr. Gross reported on the activities of the 440-H subcommittee. Currently work is being done to finalize the next revision of 440.1R including converting example problems to SI units. It is expected that the document will be sent for TAC review by April 10, 2012. He also reported that the subcommittee has initiated a task group to look at revisions to the 440.6R material specification for FRP bars. Motion: The 440-H subcommittee moved to request the chair to ask TAC for permission to develop a mandatory language design document. Upon hearing the motion, the motion was put to a vote. 22 members voted “affirmative”, 0 members voted “no”, and 0 members abstained. The motion carries. Dr. Gross then indicated that the subcommittee is planning to ballot a revision to the 440.6R document at the subcommittee level prior to the next convention and is expecting to work on developing a scope document and preliminary outline for a mandatory language design document. It is expected that the mandatory language document will not replace the current design guidelines document (440.1R). The design guidelines will provide additional details (similar to a PCA Notes document) and will include topics that are not far enough along to be considered in a mandatory language document. 440-K – Dr. Bakis reported on the activities of the 440-K subcommittee. Dr. Bakis reminded the committee that the primary mission of 440-K is to transition test methods from ACI 440.3R to ASTM standards. At ASTM, Dr. Russell Gentry is leading this effort. ASTM D 30.10 has now been formed and its scope is to address composite materials that are used in civil structures. D 30.10 bylaws are currently being balloted to allow D30 and D30.10 to be “classified” and allow these committees to develop material specifications. Dr. Bakis encouraged anyone with interest in working on test methods to join ASTM. He indicated that D30.10 will meet jointly with the 440-K subcommittee at each spring ACI Convention. Dr. Bakis indicated that the Bar Alkaline Tension test has now been successfully balloted at ASTM and will be published soon, and ASTM D 7205-06 was reaffirmed as ASTM D 7205-11. Dr. Bakis reported that there D30 is developing test standards for shear pull-off of external reinforcement, strength of embedded bars at bends, and design values for development length and bond. The shear pull-off test for external reinforcements is being led by Dr. Harries, Dr. Hamilton, Dr. Lopez de Murphy, and J. Brown. The latest version is posted on the ACI website under the 440-K subcommittee site. The bar strength at bent regions test is being led by Jon Fischer and is aiming for a ballot at D30 in 2012. Dr. Bakis also indicated that there are still several test methods in 440.3R that need to be transitioned to ASTM. These include B.7 – Tensile Fatigue, B.9 – Relaxation, B.10 – Anchorages, B.11 – Deflected Tendons, and B.12 – Corner Radius. Dr. Shield inquired about how documents are balloted at ASTM. Dr. Gentry indicated that subcommittee votes are first taken, then passed to the main committee. Dr. Shield also asked whether

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one had to join D30 in order to join D30.10. Dr. Gentry indicated that generally you do have to be a member of the main committee to join a subcommittee (but that there are provisions for consulting members to just join the subcommittee).

440-J – Dr. Shield reported that 440-J has been working on a report on stay-in-place FRP formwork. She indicated that this document is being re-drafted to potentially be a journal paper (possibly published in Concrete International). 440-M – Dr. Seracino reported on the activities of the 440-M subcommittee. Several task groups have been working on revisions of the 440.7R document. There has been significant progress on provisions for confinement of masonry and on strengthening reinforced masonry walls. The subcommittee is planning a subcommittee ballot on a revised 440.7R document during the fall of 2012. Additionally, the 440-M subcommittee is working with the 440-E subcommittee on a webinar based on the 440.7R document. Dr. Seracino requested that anyone with quality photos of masonry strengthening with FRP that can be included in this webinar e-mail those photos to him ([email protected]). Long-term tasks of the subcommittee include developing recommendations for strengthening of in-fill walls, strengthening domes/arches, and bond of FRP systems to masonry. There was also discussion at the subcommittee meeting of developing a new document on FRP reinforced masonry (new construction). Dr. Shield requested that the co-chairs of the 440-M subcommittee investigate how to better work with The Masonry Society on this document. 440-E – Dr. Belarbi reported on the activities of the 440-E subcommittee. He indicated that the webinar based on the 440.2R document is currently running on the ACI website. About 200 people

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have taken this webinar. Based on some initial feedback, some of the questions at the end of the webinar are being reviewed and revised. The webinar based on 440.1R will be posted on the website soon, and the webinar based on 440.4R is currently under review by EAC. Revisions to webinars will also need to follow any revisions to these documents. He also reiterated that 440-E is working with members of 440-M on a webinar based on 440.7R. Dr. Belarbi also mentioned that the in-person seminars may be revisited. Dr. Shield indicated that there will be activity around ACI 562 when it is published and that the in-person seminars on this document and the 440.2R document could coincide. Dr. Belarbi also indicated that the webinars could be part of course materials for student education. Dr. Shield indicated that Dr. Vicki Brown should be involved in this. 440-G – Dr. Vicki Brown reported that the next student competition would be held during the ACI Spring 2013 Convention in Minneapolis. The subcommittee is working on refining the rules of the competition, continuing to embed sustainability and cost aspects to the competition, and encouraging use of a wider variety of FRP products in the competition. There are additional rules changes that will help encourage beam solutions over arch solutions which have come to dominate the competition. Dr. Brown indicated that there will be an effort, along with the University of Minnesota, to tune up and calibrate the testing machine prior to the next competition. She also indicated that volunteers for judging and running the competition are needed! 440-I – Dr. Shield indicated that the most recent activity of this subcommittee is an interest in including recommendations on FRP post-tensioned members in the current 440.4R document. ISO TC71-SC6 – Dr. Shield reported that Committee 440 is the official US representative to ISO TC71 Subcommittee 6 (Subcommittee 6 is on FRP Reinforcement). The last ISO TC71 meeting was in June 2011 in Hong Kong. This meeting was attended by ACI 440 member Dr. Scott Smith. The TC71 chair is Dr. Ueda (Japan). The subcommittee is working to develop “Performance Guidelines for Design of Concrete Structures Using Fiber Reinforced Polymers”. The guideline is prescriptive and does not include design equations. There is currently an open ballot on this subcommittee related to renewal of two test method documents.

9. New Business No new business was discussed.

10. Next Meeting and Wrap Up

Dr. Shield informed the committee that the next meeting would be held at the ACI Fall Convention in Toronto (October 21-25, 2012) and that the convention theme is “Forming our Future”. Committee 440 will continue with the 2.5 day meeting schedule.

11. Adjourn Dr. Shield invited a motion to adjourn. Dr. Vicki Brown moved to adjourn; Mr. Gremel seconded the motion. The meeting was adjourned at 11:02am.

Respectfully submitted,

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William J. Gold Secretary, ACI Committee 440

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Appendix A – ACCELERATED CONDITIONING PROTOCOLS FOR DURABILITY

ASSESSMENT OF INTERNAL AND EXTERNAL FIBER REINFORCED POLYMER (FRP) REINFORCEMENT FOR CONCRETE

TABLE OF CONTENTS

Abstract ...........................................................................................................................................................................

CHAPTER 1― Introduction and scope ..........................................................................................................................

1.1― INTRODUCTION .................................................................................................................................................. 1.2― SCOPE ................................................................................................................................................................

CHAPTER 2― NOTATION AND DEFINITIONS ...................................................................................................

2.1― NOTATION ......................................................................................................................................................... 2.2― DEFINITIONS AND ACRONYMS ...........................................................................................................................

CHAPTER 3― DURABILITY OF FRP COMPOSITES .........................................................................................

CHAPTER 4― ACCELERATED CONDITIONING ...............................................................................................

4.1― BACKGROUND ................................................................................................................................................... 4.2― ACCELERATED CONDITIONING PROTOCOLS (ACP) ........................................................................................... 4.3― MASS CHANGE ..................................................................................................................................................

CHAPTER 5― FRP REINFORCING BARS ............................................................................................................

5.1― TENSILE STRESS TEST ........................................................................................................................................ 5.2― BENDING STRESS TEST ....................................................................................................................................... 5.3― SUSTAINED TENSILE STRESS TEST ...................................................................................................................... 5.4― ENCASED AND SUSTAINED TENSILE STRESS TEST ...............................................................................................

CHAPTER 6― EXTERNALLY BONDED FRP .......................................................................................................

6.1― TENSILE STRESS TEST ........................................................................................................................................ 6.2― PULL-OFF BOND TEST ........................................................................................................................................ 6.3― BEAM BOND TEST ..............................................................................................................................................

CHAPTER 7― FUTURE WORK/RECOMMENDATIONS/ON THE HORIZON ...............................................

7.1― ESTABLISHING RETENTION LIMITS FOR FRP REINFORCING BARS ...................................................................... 7.2― ESTABLISHING RETENTION LIMITS FOR EXTERNALLY BONDED FRP .................................................................

CHAPTER 8― REFERENCES ..................................................................................................................................

8.1― REFERENCED STANDARDS AND REPORTS ........................................................................................................... 8.2― CITED REFERENCES ...........................................................................................................................................

Documents

ACI 440 Main Minutes S12 - American Concrete Institute