August 28, 2013
TO:
PARTIES INTERESTED IN ACCEPTANCE CRITERIA FOR CONCRETE AND REINFORCED AND UNREINFORCED MASONRY STRENGTHENING USING EXTERNALLY BONDED FIBER-REINFORCED POLYMER (FRP) COMPOSITE SYSTEMS
SUBJECT:
Proposed Revisions to the Acceptance Criteria for Concrete and Reinforced and Unreinforced Masonry Strengthening Using Externally Bonded Fiber-reinforced Polymer (FRP) Composite Systems, Subject AC125-1013-R1 (ME/NH) Hearing Information: Thursday, October 17, 2013 8:00 am DoubleTree Hotel 808 South 20th Street Birmingham, AL 35205 (205) 933-9000
Dear Colleague: You are invited to comment on proposed revisions to AC125, which will be discussed at the Evaluation Committee hearing noted above. The criteria is about passive passive FRP composite systems used to strengthen existing concrete and masonry structural elements. The proposed revisions, which are detailed in the enclosed letter from the University of Miami, dated June 27, 2013, are summarized below. 1. Revisions to Section Section 1.3 for addition addition of new ASTM ASTM standards and deletion of outdated outdated ASTM standards. 2. Addition of pure axial compression strengthening test test details to Section 5.2. 3. Introduction of new ASTM standards to Section 5.17 (ASTM D7234 and D7522), and deletion of one ASTM standard (ASTM D4541). 4. Introduction of a new ASTM standard to Table 2 for glass transition temperature testing testing (ASTM E1640), and deletion of one ASTM standard (ASTM D4065). 5. Deletion from Table 3 of 10,000 hours of of aging test duration. ICC-ES Staff Comments: 1. The ICC-ES staff would like to solicit public input in regard to proposed revision revision No. 5, above. It is the staffs opinion that, unless scientific evidence demonstrating that 3000 hours aging is sufficient to make a determination about the long-term durability performance of the FRP
AC125-1013-R1 AC125-1013-R1
2
composites, environmental aging tests at 10,000 hours are still needed for this purpose and may still be used by designers and manufacturers as evidence of long-term performance. The proponent of the criteria who proposed this revision stated that this aging duration has been removed from the ACI 440 Specification Document (under development), and that this is one of their reasons for this revision to AC125, (to make the documents consistent). The ICC-ES staff would like to know why the ACI 440 committee decided to remove aging for 10,000 hours, and how this deletion impacts im pacts designers/manufacturers. 2. The following comments are in regard to glass transition temperature measurements (item No. 4, above): a. In regard to replacing ASTM D4065 with ASTM E1640, it is the staff ’s opinion ’s opinion that this effectively would not be a change at all, since the new version of D4065 (ASTM D406512) does not provide guidance on determining Tg (the old version of ASTM D4065-95 did), and the procedure for determining Tg under ASTM D4065-95 followed the procedure currently outlined in ASTM E1640 based on Loss Modulus. Therefore, existing report holders will not need to retest. b. The ICC-ES staff proposes a new footnote to Table 2 in regard to the addition of the new Tg test procedure (ASTM E1640). The footnote would say: “Tg under ASTM E1640 should be established using the Loss Modulus procedure”. This procedure”. This is needed because the new test method in ASTM E1640 is consistent with the method given in the pr evious standard, ASTM D4065. Should the committee approve the proposed r evisions to the criteria, the ICC-ES staff will not recommend a mandatory compliance date. date. Compliance with the revised criteria will will therefore be at the option of existing existing report holders. However, it should be noted that current applicants applicants for new reports will be required to address any changes that are approved by the committee. You are invited to submit written comments on this or any other agenda item, or to attend the Evaluation Committee hearing and present your views in person. If you wish to contribute contribute to the discussion, please note the following: 1. Regarding written comments: a. You should should submit these via e-mail to
[email protected] or by U.S. mail to the Los Angeles business/regional office to be received by the comments due date. b. Comments received by September 18, 2013, 2013, will be forwarded to the committee before the meeting, and also will be posted on the ICC-ES web site shortly after the deadline for submission. c. ICC-ES will also post to the web site, on October 11, 2013, 2013, comments that miss the above deadline but are received up to ten days before the meeting. meeting. On this same date, memos by the ICC-ES staff, responding to public comments, will be posted to the web site.
AC125-1013-R1
3
d. If you miss the deadline for materials to be forwarded to the committee, we can still have your comments available at the hearing if you provide 35 copies, collated, stapled, and three-hole-punched, either at the m eeting itself or to the Los Angeles business/regional office by October 11, 2013. e.
Proposed criteria, written public comments, and responses by ICC-ES staff will be available at the meeting on a limited number of CDs for uploading to computers. Also, while ICC-ES will not provide any printed copies, the hotel business center will have hard copies for photocopying.
2. Regarding verbal comments: a. If you plan to speak for more than fifteen minutes, or if you have any special needs related to a presentation, please notify ICC-ES staff as far as possible in advance. We will provide a computer, projector, and screen to anyone wishing to make a visual presentation, which in most cases should be i n PowerPoint format. b. Presentations, and any other visual aids for viewing at the meeting (transparencies, slides, videos, charts, etc.), must be provided in advance to ICC -ES, in a medium that can be retained with other records of the meeting. 3. Keep in mind that all materials submitted for committee consideration are part of the public record, and will not be treated as confidential. 4. Please do not try to communicate with any committee members before the meeting about any items on the agenda. We appreciate your interest in the work of the Evaluation Committee. If you have any questions, please contact me at (800) 423-6587, extension 3721, or Nick Horeczko, P.E., at extension 3260. You may also reach us by e-mail at
[email protected]. Yours very truly,
Mahmut Ekenel, Ph.D., P.E. Senior Staff Engineer ME/vc Encl. cc: Evaluation Committee
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ICC EVALUATION SERVICE, LLC, RULES OF PROCEDURE FOR THE EVALUATION COMMITTEE 1.0
PURPOSE
The purpose of the Evaluation Committee is to monitor the work of ICC-ES, in issuing evaluation reports; to evaluate and approve acceptance criteria on which evaluation reports may be based; and to sponsor related changes in the applicable codes. 2.0
MEMBERSHIP
2.1 The Evaluation Committee has a membership of not fewer than nine nor more than twelve, with one of the members named by the ICC-ES president each year to serve as the chairman –moderator.
All members of the committee shall be representatives of a body enforcing regulations related to the built environment. 2.2
Persons are appointed to the committee by the ICC-ES president, from among individuals who have formally applied for membership. 2.3
The ICC-ES Board of Managers, using simple majority vote, shall ratify the nominations of the president. 2.4
Committee membership is for one year, coinciding with the calendar year. Members may be renominated and reappointed, but no person shall serve for more than five consecutive terms. 2.5
In the event that a member is unable to attend a 2.6 committee meeting or complete a term on the committee, the ICC-ES president may appoint a replacement to fill in at the meeting or for the remainder of the member’s term. Any replacement appointed for only one meeting must have prior experience as a member of the Evaluation Committee. Appointments under this section (Section 2.6) are subject to ratification as noted in Section 2.4. 3.0
MEETINGS
3.1 The Evaluation Committee shall schedule meetings that are open to the public in discharging its duties under Section 1, subject to Section 3.
scheduled 3.2 All announced.
meetings
shall
be
publicly
Two-thirds of the Evaluation Committee members, 3.3 counting the chairman, shall constitute a quorum. A majority vote of members present is required on any action. To avoid any tie vote, the chairman may choose to exercise or not exercise, as necessary, his or her right to vote. In the absence of the chairman-moderator, Evaluation Committee members present shall elect an alternate chairman from the committee for that meeting. The alternate chairman shall be counted as a voting committee member for purposes of maintaining a 3.4
July 22, 2013
committee quorum and to cast a tie-breaking vote of the committee. 3.5
Minutes of the meetings shall be kept.
3.6 An electronic audio record of meetings shall be made by ICC-ES; no other audio, video, electronic or stenographic recordings of the meetings will be permitted. Visual aids (including, but not limited to, charts, overhead transparencies, slides, videos, or presentation software) viewed at meetings shall be permitted only if the presenter provides ICC-ES before presentation with a copy of the visual aid in a medium which can be retained by ICC-ES with its record of the meeting and which can also be provided to interested parties requesting a copy. A copy of the ICC-ES recording of the meeting and such visual aids, if any, will be available to interested parties upon written request made to ICC-ES together with a payment as required by ICC-ES to cover costs of preparation and duplication of the copy. These materials will be available beginning five days after the conclusion of the meeting but will no longer be available after one year from the conclusion of the meeting.
Parties interested in the deliberations of the 3.7 committee should refrain from communicating, whether in writing or verbally, with committee members regarding agenda items. All written communications and submissions regarding agenda items should be delivered to ICC-ES. All such written communications and submissions shall be considered nonconfidential and available for discussion in open session of an Evaluation Committee meeting, and shall be delivered at least ten days before the scheduled Evaluation Committee meeting if they are to be forwarded to the committee. Materials delivered to ICC-ES at least ten days before the scheduled meeting will be posted on the ICC-ES web site (www.icc-es.org) prior to the meeting. After this time, parties wishing to submit materials for consideration by the Evaluation Committee must deliver a sufficient number of copies as directed by ICC-ES. Consideration of materials not received by ICC-ES at least ten days before the meeting is at the discretion of the Evaluation Committee. Following the meeting, ICC-ES will make all materials considered by the Evaluation Committee available on the web site for a maximum period of one year following the meeting. The committee reserves the right to refuse recognition of communications which do not comply with the provisions of this section. 4.0
CLOSED SESSIONS
Evaluation Committee meetings shall be open except that the chairman may call for a closed session to seek advice of counsel. 5.0
ACCEPTANCE CRITERIA
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ICC EVALUATION SERVICE, LLC, RULES OF PROCEDURE FOR THE EVALUATION COMMITTEE
5.1 Acceptance criteria are established by the committee to provide a basis for issuing ICC-ES evaluation reports on products and systems under codes referenced in Section 2.0 of the Rules of Procedure for Evaluation Reports. They also clarify conditions of acceptance for products and systems specifically regulated by the codes.
3. Other acceptance criteria and/or the code provide precedence for the revised criteria. Negative votes must be based upon one or more 6.2 of the following, for the ballots to be considered valid and require resolution: a. Lack of clarity : There is insufficient explanation of the scope of the acceptance criteria or insufficient description of the intended use of the product or system; or the acceptance criteria is so unclear as to be unacceptable. (The areas where greater clarity is required must be specifically identified.)
Acceptance criteria may involve a product, material, method of construction, or service. Consideration of any acceptance criteria must be in conjunction with a current and valid application for an ICC-ES evaluation report, an existing ICC-ES evaluation report, or as otherwise determined by the Evaluation Committee.
b. Insufficiency : The criteria is insufficient for proper evaluation of the product or system. (The provisions of the criteria that are in question must be specifically identified.)
EXCEPTIONS: The following acceptance criteria are controlled by the ICC-ES executive staff and are not subject to committee approval:
c. The subject of the acceptance criteria is not within the scope of the applicable codes: A report issued by ICC-ES is intended to provide a basis for approval under the codes. If the subject of the acceptance criteria is not regulated by the codes, there is no basis for issuing a report, or a criteria. (Specifics must be provided concerning the inapplicability of the code.)
The Acceptance Criteria for Quality Documentation (AC10) The Acceptance Criteria for Test Reports (AC85) The Acceptance Criteria for Inspections and Inspection Agencies (AC304) 5.2
Procedure:
5.2.1 Proposed acceptance criteria shall be developed by the ICC-ES staff and discussed in open session with the Evaluation Committee during a scheduled meeting, except as permitted in Section 5.0 of these rules.
d. The subject of the acceptance criteria needs to be discussed in public hearings. The committee member requests additional input from other committee members, staff or industry.
Proposed acceptance criteria shall be 5.2.2 available to interested parties at least 30 days before discussion at the committee meeting.
6.3 An Evaluation Committee member, in voting on an acceptance criteria, may only cast the following ballots:
The committee shall be informed of all pertinent written communications received by ICC-ES. 5.2.3
Attendees at Evaluation Committee meetings shall have the opportunity to speak on acceptance criteria listed on the meeting agenda, to provide information to committee members. 5.2.4
5.3 Approval of acceptance criteria shall be as specified in Section 3.3 of these ru les. 5.4 Actions of the Evaluation Committee may be appealed in accordance with the ICC-ES Rules of Procedure for Appeal of Acceptance Criteria or the ICCES Rules of Procedure for Appeals of Evaluation Committee Technical Decisions.
COMMITTEE BALLOTING FOR ACCEPTANCE CRITERIA 6.0
6.1 Acceptance criteria may be issued without a public hearing following a 30-day public comment period and a majority vote for approval by the Evaluation Committee when, in the opinion of ICC-ES staff, one or more of the following conditions have been met:
1. The subject is nonstructural, does not involve life safety, and is addressed in nationally recognized standards or generally accepted industry standards. 2. The subject is a revision to an existing acceptance criteria that requires a formal action by the Evaluation Committee, and public comments raised were resolved by staff with commenters fully informed.
7.0
•
Approved
•
Approved with Comments
•
Negative: Do Not Proceed COMMITTEE COMMUNICATION
Direct communication between committee members, and between committee members and an applicant or concerned party, with regard to the processing of a particular acceptance criteria or evaluation report, shall take place only in a public hearing of the Evaluation Committee. Accordingly: Committee members receiving an electronic ballot 7.1 should respond only to the sender (ICC-ES staff). Committee members who wish to discuss a particular matter with other committee members, before reaching a decision, should ballot accordingly and bring the matter to the attention of ICC-ES staff, so the issue can be placed on the agenda of a future committee meeting. Committee members who are contacted by an 7.2 applicant or concerned party on a particular matter that will be brought to the committee will refrain from private communication and will encourage the applicant or concerned party to forward their concerns through the ICC-ES staff in writing, and/or make their concerns known by addressing the committee at a public hearing, so that their concerns can receive the attention of all committee members.■
E ffective J uly 22, 2013
July 22, 2013
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A Subsidiary of the International Code Council ®
PROPOSED REVISIONS TO THE ACCEPTANCE CRITERIA FOR CONCRETE AND REINFORCED AND UNREINFORCED MASONRY STRENGTHENING USING EXTERNALLY BONDED FIBER-REINFORCED POLYMER (FRP) COMPOSITE SYSTEMS AC125
Proposed August 2013
Previously revised June 2012, February 2010, October 2009, June 2007, June 2003, April 1997
PREFACE Evaluation reports issued by ICC Evaluation Service, LLC (ICC-ES), are based upon performance features of the International family of codes. (Some reports may also reference older code families such as the BOCA ® National Codes, the Standard Codes, and the Uniform Codes.) Section 104.11 of the International Building Code reads as follows: The provisions of this code are not intended to prevent the installation of any materials or to prohibit any design or method of construction not specifically prescribed by this code, provided that any such alternative has been approved. 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 this code, and that the material, method or work offered is, for the purpose intended, at least the equivalent of that prescribed in this code in quality, strength, effectiveness, fire resistance, durability and safety. ICC-ES may consider alternate criteria for report approval, provided the report applicant submits data demonstrating that the alternate criteria are at least equivalent to the criteria set forth in this document, and otherwise demonstrate compliance with the performance features of the codes. ICC-ES retains the right to refuse to issue or renew any evaluation report, if the applicable product, material, or method of construction is such that either unusual care with its installation or use must be exercised for satisfactory performance, or if malfunctioning is apt to cause injury or unreasonable damage. NOTE: The Preface for ICC-ES acceptance criteria was revised in July 2011 to reflect changes in policy.
Acceptance cr iter ia are developed for us e solely by IC C-E S for pur pos es of i s s uing IC C -E S ev aluation r eports
PROPOSED REVISIONS TO THE ACCEPTANCE CRITERIA FOR CONCRETE AND REINFORCED AND UNREINFORCED MASONRY STRENGTHENING USING EXTERNALLY BONDED FIBER-REINFORCED POLYMER (FRP) COMPOSITE SYSTEMS (AC125) 1.0
INTRODUCTION
1.3.11 ASTM D2584-94, Test Method for Ignition
Loss of Cured Reinforced Resins, ASTM International.
1.1
Purpose: The purpose of this criteria is to establish minimum requirements for the issuance of ICC Evaluation Service, LLC (ICC-ES), evaluation reports on fiber-reinforced polymer (FRP) composite systems under ® the 2012, 2009 and 2006 International Building Code (IBC) and the 1997 Uniform Building Code™ (UBC). Bases of recognition are IBC Section 104.11 and UBC Section 104.2.8.
1.3.12 ASTM D2990-95, Test Methods for Tensile, Compressive, and Flexural Creep and Creep Rupture of Plastics, ASTM International. 1.3.13 ASTM D3029-94, Standard Test Methods for Impact Resistance of Flat, Rigid Plastic Specimens by Means of a Tup (Falling Weight), ASTM International.
1.3.15 ASTM D3045-92, Standard Practice for Heat Aging of Plastics Without Load, ASTM International. 1.3.16 ASTM D3083-89, Specification for Flexible Poly (Vinyl Chloride) Plastic Sheeting for Pond, Canal, and Reservoir Lining, ASTM International.
1.2
Scope: This acceptance criteria applies to passive FRP composite systems used to strengthen existing concrete and masonry structural elements. Properties evaluated include flexural, and shear capacities, performance under environmental exposures, performance under exposure to fire conditions, and structural design procedures. 1.3
1.3.17 ASTM D3165-95, Standard Test Method for Strength Properties of Adhesives in Shear by Tension Loading of Single-Lap-Joint Laminated Assemblies, ASTM International. 1.3.18 ASTM D3171-95, Standard Test Method for Constituent Content of Composite Materials, ASTM International.
Referenced Codes and Standards:
1.3.1
2012, 2009 and 2006 International Building Code (IBC), International Code Council. ®
1.3.2
1997 Uniform Building Code™ International Conference of Building Officials.
2
ASTM D3039-00 , Standard Test Method for Tensile Properties of Polymer Matrix Composite Materials, ASTM International. 1.3.14
The reason for the development of this criteria is to provide guidelines for the evaluation of alternative concrete and masonry structural systems, where the codes do not provide requirements for testing and determination of structural capacities, reliability and serviceability of these products.
1.3.19 ASTM D4065-95, Standard Practice for Determining and Reporting Dynamic Mechanical Properties of Plastics, ASTM International.
(UBC),
1.3.20 ASTM D4541-02, Standard Test Method for Pull-off Strength of Coatings Using Portable Adhesion Testers, ASTM International.
ICC-ES Acceptance Criteria for Inspection and 1.3.3 Verification of Concrete and Reinforced and Unreinforced Masonry Strengthening Using Fiber-reinforced Polymer (FRP) Composite Systems (AC178). 1.3.4
1.3.19 ASTM D7234-12, Standard Test Method for Pull-Off Adhesion Strength of Coatings on Concrete Using Portable Pull-Off Adhesion Testers, ASTM International.
1.3.5
1.3.20 ASTM D7522-09, Standard Test Method for Pull-Off Strength for FRP Bonded to Concrete Substrate, ASTM International.
ASTM C297-94, Test Method for Tensile Strength of Flat Sandwich Constructions in Flatwise Plane, ASTM International. ASTM C581-94, Practice for Determining the Chemical Resistance of Thermosetting Resins Used in Glass-Fiber-Reinforced Structures Intended for Liquid Service, ASTM International.
1.3.21 ASTM E104-85 (1996), Standard Practice for Maintaining Constant Relative Humidity by Means of Aqueous Solutions, ASTM International.
ASTM D696-91, Standard Test Method for 1.3.6 Coefficient of Linear Thermal Expansion of Plastics Between -30C and 30C with a Vitreous Silica Dilatometer, ASTM International.
1.3.22 ASTM E831-00, Standard Test Method for Linear Thermal Expansion of Solid Materials by Thermomechanical Analysis, ASTM International.
1.3.7
ASTM D1141-91, Practice for Preparation of Substitute Ocean Water, ASTM International.
Standard Terminology 1.3.23 ASTM E1142-97, Relating to Thermophysical Properties, ASTM International.
ASTM D2247-97, Practice for Testing Water 1.3.8 Resistance of Coatings in 100% Relative Humidity, ASTM International.
1.3.24 ASTM E1640-09, Standard Test Method for Assignment of the Glass Transition Temperature by Dynamic Mechanical Analysis. ASTM International.
ASTM D2344-84 (1995), Test Method for 1.3.9 Apparent Interlaminar Shear Strength of Parallel Fiber Composites by Short-Beam Method, ASTM International.
1.3.25
1.3.24 ASTM G153-04 Standard Practice for Operating Enclosed Carbon Arc Light Apparatus for Exposure of Nonmetallic Materials, ASTM International.
1.3.10 ASTM D2565-99 (2008), Standard Practice for Xenon-Arc Exposure of Plastics Intended for Outdoor Applications, ASTM International.
2.0
2
DEFINITIONS
PROPOSED REVISIONS TO THE ACCEPTANCE CRITERIA FOR CONCRETE AND REINFORCED AND UNREINFORCED MASONRY
STRENGTHENING USING EXTERNALLY BONDED FIBER-REINFORCED POLYMER (FRP) COMPOSITE SYSTEMS (AC125)
Design Values: The FRP composite material’s 2.1 load and deformation design capacities, that are based on either working stress or ultimate strength methods.
analysis. The engineering analysis shall define failure modes or force and deflection limit states. 5. Use of anchors shall be considered where the FRP composite material bond to substrate is critical.
2.2
Composite Material: A combination of highstrength fibers and polymer matrix material. This FRP composite may be applied either during manufacture of the structural element or at the project location.
4.0
TESTING LABORATORIES AND REPORTS OF TESTS 4.1
Testing laboratories shall comply with Section 2.0 of the ICC-ES Acceptance Criteria for Test Reports (AC85) and Section 4.2 of the ICC-ES Rules of Procedure for Evaluation Reports.
2.3
Cracking Load and Displacement: Load and displacement at which the moment-curvature relationship of the concrete or masonry section first changes slope or at which the cracking moment is reached.
4.2
2.4
Yielding Load and Displacement: Load and displacement at which longitudinal steel reinforcement of the concrete or masonry section first yields.
Product Sampling: Products shall be sampled in 4.3 accordance with Section 3.1 of AC85. 5.0
Passive and Active Composite Systems: Active 2.5 systems are those FRP composite systems where the FRP composite materials are post-tensioned after installation by means such as pressure injection between the composite material and the concrete or masonry section. Passive systems are not post-tensioned after installation. Active systems are outside the scope of this criteria. 3.0
Qualification Test Plan: The intent of testing is to verify the design equations and assumptions used in the engineering analysis. All or part of the tests described in this section, and any additional tests identified for special features of the product or system, shall be specified. The test plan shall be a complete document. Overall, qualification testing must provide data on material properties, force and deformation limit states, and failure modes, to support a rational analysis procedure. The specimens shall be constructed under conditions specified by the manufacturer, including curing. Tests must simulate the anticipated loading conditions, load levels, deflections, and ductilities.
Description: A detailed description of the 3.1 strengthening system is needed, including the following items: 1. Description and identification of the product or system. Identification shall include the ICC-ES evaluation report number.
5.2
Columns:
5.2.1
2. Restrictions or limitations on use. Instructions
QUALIFICATION TESTS
5.1
REQUIRED INFORMATION
Installation Instructions: 3.2 include the following items.
Test reports shall comply with AC85.
Flexural Tests:
Configuration: Column specimens shall 5.2.1.1 be configured to induce flexural limit states or failure modes. Either cantilever or double fixity (reverse curvature) is permitted in specimens. Extremes of dimensional, reinforcing, and strength parameters shall be considered.
shall
1. Description of how the product or system will be used or installed in the field. 2. Procedures establishing quality control in field installation.
5.2.1.2
Procedure: For seismic or wind-load applications, the lateral load procedure shall conform to Figure 3. For gravity (nondynamic) loading applications, the load may be monotonically applied. Axial loads within a specific range shall be applied. The limit states shall be determined based on material properties and an extreme concrete or masonry fiber compression strain of 0.003.
3. Requirements for product handling and storage. 4. Fastener installation into structural elements. 5. For systems that depend on bond between the system and the substrate, on-site testing of bond to the substrate is required. Structural Design: The structural applications of 3.3 the system shall address the following items:
5.2.2
Shear Tests:
Configuration: Column specimen spans 5.2.2.1 shall be configured to induce shear limit states or failure modes. Either double fixity (reverse curvature) or cantilever is required. Extremes of dimensional, reinforcing, and compressive strength parameters shall be considered.
1. Clarification of recognition under either Chapter 19 or Chapter 21 of the IBC or UBC. 2. Complete description of details. 3. Details on how the product or system does or does not comply with Chapter 19 of the IBC or UBC, including conformities and deviations. Details shall include positive statements that the product or system does comply with Chapter 19 or 21 of the IBC or UBC in the following areas . . . ; and negative statements that it does not comply in the following areas. . . .
Procedure: For seismic or wind-load 5.2.2.2 application, the lateral load procedure shall conform to Figure 3. For g ravity (nondynamic) loading application, the load may be monotonically applied. Axial loads within a specific range shall be applied. The limit states shall be determined based on material properties.
4. Details and examples of how the product or system is designed and analyzed, including formulas, with procedures and properties needed for design and
5.2.3
Pure Axial Tests
Configuration: Column specimens shall 5.2.3.1 be configured to induce axial compression limit states or 3
PROPOSED REVISIONS TO THE ACCEPTANCE CRITERIA FOR CONCRETE AND REINFORCED AND UNREINFORCED MASONRY
STRENGTHENING USING EXTERNALLY BONDED FIBER-REINFORCED POLYMER (FRP) COMPOSITE SYSTEMS (AC125)
Load specimens in both directions, to 5.5.1.2.1 find cracking and yielding load and deformation at first cracking. For unreinforced masonry, only cracking load and deformation are required.
failure modes as related to FRP performance. Extremes of dimensional, FRP reinforcing, and strength parameters of the concrete columns to be strengthened by FRP shall be considered. Procedure: The load shall be 5.2.3.2 monotonically applied. The limit states shall be determined based on geometric, material properties and column end support conditions. 5.3
5.5.1.2.2
At least two cycles of loading in both directions under displacement control at each deformation level. The deformation levels shall consist of multiples of the deformation at yielding for reinforced concrete or masonry sections or cracking for unreinforced masonry sections.
Beam-to-Column Joints:
Configuration: The beam-to-column joint 5.3.1 shall be configured to induce joint-related limit states or failure modes. The column portion may be constructed to represent a section between inflection points. Extremes of dimensional, reinforcing and compressive strength parameters shall be considered.
The specimens are loaded in both 5.5.1.2.3 directions until the strengthening system is damaged, its capacity is reached, or desired limit states are achieved. 5.5.2
Configuration: Wall specimens shall be 5.5.2.1 configured to induce in-plane shear limit states or failure modes. Extremes of dimensional, reinforcing and compressive strength parameters shall be considered.
5.3.2
Procedure: The lateral load procedure shall conform to Figure 3. A vertical load shall be continuously applied and varied within a specified range. The limit states shall be determined based on material properties. 5.4
Procedure: Specimens may by axially 5.5.2.2 loaded to consider effects of axial loads. The lateral load procedure consists of:
Beams:
5.4.1
Flexural Tests:
Load specimens in both directions to 5.5.2.2.1 find cracking and yielding load and deformation. For unreinforced masonry, only cracking load and deformation are required.
Configuration: Beam spans shall be 5.4.1.1 configured to induce flexural limit states or failure modes. Either simple or rigid supports are permitted. Extremes of dimensional, reinforcing, and compressive strength parameters shall be considered.
The specimens are loaded in both 5.5.2.2.2 directions until the strengthening system is damaged, its capacity is reached, or desired limit states are achieved.
5.4.1.2
Procedure: For seismic or wind-load application, the lateral load procedure shall conform to Figure 3. For gravity (nondynamic) loading application, the load may be monotonically applied. The limit states shall be determined based on material properties and an extreme concrete or masonry fiber compression strain of 0.003. 5.4.2
5.6
Shear Tests:
Procedure: For seismic or wind-loading 5.6.2 applications, the lateral load procedure shall conform to Figure 3. For gravity load applications, the load may be monotonically applied. The vertical load shall be applied to floors. The limit states shall be determined based on material properties.
Configuration: Beam spans shall be configured to induce shear limit states or failure modes. Either simple or rigid supports are permitted. Extremes of dimensional, reinforcing, and compressive strength parameters shall be considered.
5.7
5.4.2.2
Procedure: For seismic or wind loading, the lateral load procedure shall conform to Figure 3. For gravity loading, the load may be monotonically applied. The limit states shall be determined based on material properties.
Slabs (Flexural Tests):
Configuration: Slab spans shall be configured 5.7.1 to include flexural limit states or failure modes. Either simple or rigid supports are permitted. Extremes of dimensional, reinforcing and compressive strength shall be considered.
Walls:
5.5.1
Wall-to-Floor Joints:
Configurations: The specimens shall be 5.6.1 configured to induce joint-related limit states or failure modes. Extremes of dimensional, reinforcing and compressive strength parameters shall be considered.
5.4.2.1
5.5
Wall Shear Tests (In-Plane Shear):
Procedure: For seismic or wind-load 5.7.2 applications, the lateral load procedure shall conform to Figure 3. For g ravity (nondynamic) loading application, the load may be monotonically applied. The limit states shall be determined based on material properties and an extreme concrete fiber compression strain of 0.003.
Wall Flexural Tests (Out-of-Plane Load):
Configuration: Wall flexural specimens 5.5.1.1 shall be configured to induce out-of-plane flexural limit states and failure modes. Extremes of dimensional, reinforcing, and compressive strength parameters shall be considered.
5.8
Physical and Mechanical Properties of FRP Composite Materials: Required physical and mechanical properties are shown in Table 2. These properties, including creep, CTE and impact, shall be considered in the design criteria and limitations.
Procedure: Specimens may be axially 5.5.1.2 loaded to consider effects of axial loads. The loading in the out-of-plane direction may be applied at third-points, by air-bags or by other means representing actual conditions. The lateral load procedure consists of:
4
PROPOSED REVISIONS TO THE ACCEPTANCE CRITERIA FOR CONCRETE AND REINFORCED AND UNREINFORCED MASONRY
STRENGTHENING USING EXTERNALLY BONDED FIBER-REINFORCED POLYMER (FRP) COMPOSITE SYSTEMS (AC125) 5.9
Exterior Exposure:
for tensile strength, tensile modulus, and elongation according to ASTM D3039.
Procedure: Structural FRP composite 5.9.1 materials are tested according to ASTM G153 or ASTM 3 D2565. Six specimens, measuring /4 inch by 10 inches (19.1 by 254 mm), are required. These specimens also may be cut from a panel that has been coated and painted to represent end-use conditions. Five specimens are exposed to cycles consisting of 102 minutes light and 18 minutes light and water spray in the weatherometer chamber. Minimum duration is 2,000 hours. The blackbody temperature is 145°F (63°C). Both exposed and control specimens are then tested to ASTM D3039, for tensile strength, tensile modulus and elongation. Five other specimens are controlled samples.
5.12.2 Conditions of Acceptance: Conditioned and exposed specimens are visually examined using 5× magnification. Surface changes, such as erosion, cracking, crazing, checking, and chalking, are unacceptable. The exposed specimens shall retain at least 90 percent of tensile properties generated on conditioned specimens. 5.13 Fire-resistant Construction: The effect of the FRP composite system on fire-resistance construction shall be evaluated according to Section 703 of the IBC or UBC. 5.14 Interior Finish: The classification of the fiberreinforced polymer (FRP), composite system as an interior finish shall be determined according to Section 803 of the IBC or Section 802 of the UBC.
5.9.2
Conditions of Acceptance: Control and exposed specimens are visually examined using 5× magnification. Surface changes affecting performance, such as erosion, cracking, crazing, checking, and chalks, are subject to further investigation. The specimens shall retain at least 90 percent of tensile properties generated on control specimens.
5.15 Fuel Resistance: Tested specimens are tested
according to ASTM C581. The specimens are exposed to diesel fuel reagent for 4 hours, minimum. Specimens are tested according to Table 2 for tensile strength, tensile modulus, elongation, glass transition temperature, and interlaminar shear strength.
5.10 Freezing and Thawing: 5.10.1 Procedure: Fifteen samples are conditioned in a 100 percent relative humidity chamber at 100°F (38°C) for three weeks. Each cycle is 4 hours, minimum, in a 0°F (-18°C) freezer followed by 12 hours, minimum, in the humidity chamber. At least twenty cycles are required.
5.16 Adhesive Lap Strength: This test applies to prefabricated systems. Specimens of the adhesive are tested according to ASTM D3165 for exposures in Table 3, and Sections 5.10 and 5.15.
Control specimens and cycled specimens are then tested according to Table 2 for tensile strength, tensile modulus, elongation, glass transition temperature, and interlaminar shear strength. Specimens are tested in the primary direction.
5.17 Bond Strength: 5.17.1 Procedure: The test applies to systems that bond to the substrate. Tests are conducted for tension according to ASTM D4541 D7234 or ASTM C297 or ASTM D7522 where the composite material bonds two substrate elements together, and for shear using a method acceptable to ICC-ES staff. Specimens are exposed according to Table 3 and Section 5.10.
of Acceptance: Control 5.10.2 Conditions specimens and cycled specimens are visually examined using 5× magnification. Surface changes affecting performance, such as erosion, cracking, crazing, checking and chalking, are unacceptable. The cycled specimens shall retain at least 90 percent of the tensile properties determined for conditioned specimens.
5.17.2
Conditions of Acceptance: The bond strength of FRP composite material to concrete shall not be less than 200 psi (1378 kPa). The bond strength of the FRP composite material to masonry shall not be less than 0.5 2.5 x ( f’ m) . In both cases, bond testing shall exhibit failure in the concrete or masonry substrate.
5.11 Aging: These tests shall be considered in design criteria and limitations. 5.11.1 Procedure: Both wet and dry specimens are aged according to Table 3. Both exposed and control specimens are then tested to Table 2 for tensile strength, tensile modulus, elongation, glass transition temperature, and interlaminar shear strength. Specimens are tested in the primary direction. Five specimens per condition are required.
5.18 Drinking Water Exposure: The effect of the FRP composite system when directly exposed to drinking water shall be evaluated based in tests in accordance with NSF 61. 6.0
QUALITY CONTROL
Manufacturing: Quality assurance procedures 6.1 during manufacture of the system components shall be described in a quality control manual complying with the ICC-ES Acceptance Criteria for Quality Documentation (AC10). The quality control program shall include periodic inspections by an inspection agency currently accredited by the International Accreditation Service, Inc. (IAS).
5.11.2
Conditions of Acceptance: Control and exposed specimens are visually examined using 5× magnification. Surface changes affecting performance, such as erosion, cracking, crazing, checking, and chalking, are unacceptable. The exposed specimens shall retain the percentage of tensile properties generated on conditioned specimens noted in Table 3.
Installation: All installations shall be done by 6.2 applicators approved by the proponent of the system. The quality assurance program shall be documented and comply with AC178. Special inspection is required and shall comply with Section 1704 of the IBC or Section 1701 of the UBC and other sections of the applicable code.
5.12 Alkali Soil Resistance: 5.12.1
Procedure: Tests are done on five specimens according to ASTM D3083, Section 9.5, for 1,000 hours. Both conditioned and exposed specimens are then tested 5
PROPOSED REVISIONS TO THE ACCEPTANCE CRITERIA FOR CONCRETE AND REINFORCED AND UNREINFORCED MASONRY
STRENGTHENING USING EXTERNALLY BONDED FIBER-REINFORCED POLYMER (FRP) COMPOSITE SYSTEMS (AC125)
Duties of the special inspector shall be described and included in the evaluation report. FINAL SUBMITTAL
7.0
Crushing of the concrete in compression before yielding of the reinforcing steel.
Yielding of the steel in tension followed by rupture of the FRP laminate.
Yielding of the steel in tension followed by concrete crushing.
Shear/tension delamination of the concrete cover (cover delamination).
Debonding of the FRP from the concrete substrate (FRP debonding).
7.1
The final submittal will consist of a test report or test reports, and a design criteria report, as described in this section. The final submittal shall include the data described in Section 3 of this criteria. Contents of the final submittal are described in the following subsections: Test Report: The independent laboratory shall 7.2 report on the qualification testing performed according to the approved test plan. Besides the information requested in Section 4, the test report must include the following:
The effective strain in FRP reinforcement shall be limited to the strain level at which debonding may occur, ε fd , as defined in Eq. (1a):
1. Information noted in the reference standard. 2. Description of test setup.
fd 0.083
3. Rate and method of loading. 4. Deformation and strain measurements. 5. Modes of failure.
ε
6. Strain measurements. 7.3
fd
0.41
Design Criteria:
nE f t f
0.9 fu
f c ' nE f t f
(1a)
0.9ε fu (SI Units)
The nominal effective stress level in the FRP reinforcement shall be calculated in accordance with Equation (1b):
7.3.1
Design Criteria Report: The report shall include a complete analysis and interpretation of the qualification test results. Design stress and strain criteria for concrete and reinforced and unreinforced masonry systems shall be specified based on the analyses, but shall not be higher than specified in Section 7.3.2.
f fe =0.85.E f. ε fe where ε fe ≤ ε fd
(1b)
Checks must be done to ensure that the strain in the member is at least as high as what is assumed in design. Fibers shall not have a misalignment of more than 5 degrees.
Design stresses and strains shall be based on a characteristic value approach verified by test data. The CTE values determined in Table 2 shall be considered in the design procedure. The creep rupture stress limits as shown in Table 1 shall be considered in the design procedure.
Dependable flexural strengths shall be determined by multiplying the nominal flexural strength, including the effects of fiber according to Equation (1b), by the appropriate flexural strength reduction factor according to the IBC or UBC.
The design criteria report shall provide guidance on protecting the composite materials in areas where they are prone to impact. The design shall consider secondary stresses resulting when dead loads are relieved during application and subsequently reapplied. Adoption of the minimum acceptable standards for design outlined in Section 7.3.2 does not eliminate the need for structural testing.
Design moment capacity for flexure shall be calculated in accordance with Equation (1c). øMn = ø(Ms+Mf )
(1c)
Serviceability: The stress in the steel 7.3.2.1.1 reinforcement under service load shall be limited to 80 percent of the yield strength.
Situations not covered in Section 7.3.2 shall be subject to special considerations and testing, and design values shall be compatible with the conservative approach adopted in Section 7.3.2, and discussed in reference [4]. 7.3.2
f c
f s , s 0.80 f y
(2)
7.3.2.1.2
Creep Rupture and Fatigue Stress Limits: The service stress levels in the FRP reinforcement under service load shall the lesser of the analysis of creep test in accordance with Table 2 or the maximum values in Table 1.
Minimum Acceptable Design Criteria:
Flexural Strength Enhancement of 7.3.2.1 Reinforced Concrete Members: Fiber-reinforced polymer (FRP) composite material bonded to surfaces of concrete may be used to enhance the design flexural strength of sections by acting as additional tension reinforcement. In such cases, section analysis shall be based on normal assumptions of a) plane sections remain plane after loading; b) the bond between the FRP and the substrate remains perfect; c) the maximum usable compressive strain in the concrete is 0.003; d) FRP has a linear elastic behavior to failure.
Flexural Strength Enhancement of 7.3.2.2 Masonry Elements: The flexural strength of a masonry element strengthened with FRP shall be based on the assumptions presented in Section 7.3.2.1. However, the effective strain in FRP reinforcement shall be limited to the strain level at which debonding may occur as defined in Equations (3a) and (3b):
The flexural strength of a reinforced concrete section depends on the controlling failure mode. Failure modes for an FRP-strengthened section include: 6
fe 0.45 fu
(3a)
f fe E f fe
(3b)
PROPOSED REVISIONS TO THE ACCEPTANCE CRITERIA FOR CONCRETE AND REINFORCED AND UNREINFORCED MASONRY
STRENGTHENING USING EXTERNALLY BONDED FIBER-REINFORCED POLYMER (FRP) COMPOSITE SYSTEMS (AC125)
The force per unit width provided by FRP shall be determined from Equation (4).
In Equation (9), the efficiency factor, b, shall be calculated using Equation (10b). Circular Sections: For circular cross 7.3.2.3.1 sections the shape factors a and b in Equations (6) and (9), respectively, shall be taken as 1.0.
(4) (SI units)
Rectangular Sections: Rectangular 7.3.2.3.2 sections where the ratio of longer to shorter section side dimension is not greater than 2.0, may have axial compression capacity enhanced by the confining effect of FRP composite material placed with fibers running essentially perpendicular to the members’ axis. For rectangular sections confined with transverse FRP composite material, section corners must be rounded to a 3 radius not less than /4 inch (20 mm) before placing FRP composite material. Axial compression capacity enhancement by FRP composite material to rectangular sections within aspect ratio h/b > 2.0 shall be subject to special analysis confirmed by test results.
7.3.2.3
Axial Load Capacity Enhancement: FRP composite material may be bonded to external surfaces of concrete or masonry members to enhance axial load capacity. The stress-strain for FRP-confined concrete is illustrated in Figure 1 and shall be determined using the following expressions: 2 Ec E 2 2 E c f c c c 4 f c f c E 2 c
t
2 f c Ec E 2
E 2
(5a)
The shape factors a in Equation (6) and b in Equation (9) shall be calculated using Equation (10), and is shown in Figure 2.
t c ccu
f cc f c ccu
0 c t
(5b)
(5c)
2nt f E f fe D f l 2nt E f f fe 2 2 b h
0.5
(10a)
(10b)
(10c)
(6)
Ductility Enhancement: FRP composite 7.3.2.4 material oriented essentially transversely to the members’ axis may be used to enhance flexural ductility capacity of circular and rectangular sections where the ratio of longer to shorter section dimension does not exceed 2.0. The enhancement is provided by increasing the effective ultimate compression strain of the section.
Circular Cross-section (7)
Non-circular Cross-section
7.3.2.4.1
Circular Sections: Ultimate compression strain of circular sections of diameter D, confined with fiber of effective thickness t f at angle θ = 90° to the longitudinal axis of the member, shall be given by
(8)
εcu
The minimum confinement ratio f l /f’ c shall not be less than 0.08.
0.45 f l fe c 1.5 12 b 0.01 f c c
= 0.004 +
2.5sj
f uj uj
(11)
f cc where f cc is given by Equation (6), and ρsj is (4tf /D).
The maximum compressive strain in the FRPconfined concrete, ccu, shall not exceed 0.01 to prevent excessive cracking and the resulting loss of concrete integrity. The corresponding maximum value of f ′c c shall be calculated using the following stress-strain relationship:
ccu
A h b e Ac b
[() ()]
In Equation (7), the effective strain level in the FRP at failure, fe, shall be given by: fe = fu
2
where,
The maximum confined concrete compressive strength, f’ cc , and the maximum confinement pressure, f l , shall be calculated using Equations (6) and (7), respectively with the inclusion of an additional reduction factor, f = 0.95.
f cc f c f 3.3 a f l
A b a e Ac h
Rectangular Sections: Ultimate 7.3.2.4.2 compression strains of rectangular sections of side lengths B and H where H ≤ 1.5B, and with fiber of effective thickness t f at an angle θ to the longitudinal axis of the member, shall be given by
(9) εcu = 0.004 + 7
1.25sj
f uj uj
f cc
(12)
PROPOSED REVISIONS TO THE ACCEPTANCE CRITERIA FOR CONCRETE AND REINFORCED AND UNREINFORCED MASONRY
STRENGTHENING USING EXTERNALLY BONDED FIBER-REINFORCED POLYMER (FRP) COMPOSITE SYSTEMS (AC125)
where f 'cc is given by Equation (6) and ρ sj is 2tf [(B+H)/BH].
0.85 for three-sided FRP U-wrap or two-sided strengthening schemes;
For rectangular sections confined with transverse FRP composite material, section corners must be rounded 3 to a radius of not less than /4 inch (20 mm) before placing FRP composite material. Ductility enhancement according to Equation (12) shall not be relied on for slender members where the aspect ratio M/VB ≥ 3.
0.95 for fully wrapped sections.
V n V c V s f V f
ρsj ≥
(17)
The shear contribution of the FRP shear reinforcement shall given by Equation (18)
Lap-Splice Confinement: Lap-splices in 7.3.2.5 circular columns can be confined by jackets to prevent bond failure. The required volumetric ratio of FRP composite material, at an angle θ to the longitudinal axis of the member (ρsj ) shall not be less than 1.4 Ab
V f
A fv f fe (sinα cosα)d fv s f
(18)
where:
f s
(13)
pl s f j
Afv = 2nt fw f f fe = feE f
where p is the perimeter of the crack surface forming before splice failure given by the lesser of Equations (14) and (15):
( )
√ ( )
The effective design strain fe is the maximum strain that shall be achieved in the FRP system at the nominal strength and is governed by the failure mode of the FRP system and of the strengthened reinforced concrete member.
(14)
fe = 0.004 0.75 fu for completely wrapped members
(15)
In Equation (13), the circular section is reinforced with n bars each of diameter d b, area Ab, uniformly distributed around the section on core diameter D’ . Required stress to be transferred is f s, and the splice length l s must not be less than l s
≥ 0.025d b
f y
fe = v f u 0.004 for 2-sides or 3-sides (U-wrapped) members
The bond-reduction coefficient shall be computed from Equations (19) through (22): κ v
(16)
f c κ v
For SI: s =
0.3 d b f y
f cu
Le
The jacket stress f j in Equation (13) shall not be taken larger than f j = 0.0015E j ≤ 0.75 f uj .
Le
Note: Rectangular sections cannot generally be effectively confined by rectangular jackets against splice failure, and so no provisions are included here.
k 1k 2 Le 468ε fu
Shear Strength Enhancement of Concrete Elements: Shear strength of circular and rectangular sections of concrete elements can be enhanced by FRP composite materials with fiber oriented essentially perpendicular to the members’ a xis.
k 1k 2 Le
(19)
0.75
11,900ε fu
(SI Units)
2500 (n f t f E f )
0.58
(20)
23,300 (n f t f E f )
f c ' 4000
7.3.2.6
0.75
0.58
(SI Units)
2/3
k 1
f ' k 1 c 27
Shear strengthening using external FRP may be provided at locations of expected plastic hinges or stress reversal and for enhancing post-yield flexural behavior of members in moment frames resisting seismic loads only by completely wrapping the section. For external FRP reinforcement in the form of discrete strips, the center-tocenter spacing between the strips shall not exceed the sum of d/4 plus the width of the strip.
2/3
1 for Completely wrapped d L fv e k 2 for U - wrapped d fv d 2 L e fv for two sides bonded d fv
The design shear strength of an FRP-strengthened concrete member can be determined using Eq. (17). An additional reduction factor shall be applied to the contribution of the FRP system, as follows:
(21)
(SI Units)
(22)
The total shear strength provided by FRP and steel reinforcement shall be limited to the following: 8
PROPOSED REVISIONS TO THE ACCEPTANCE CRITERIA FOR CONCRETE AND REINFORCED AND UNREINFORCED MASONRY
STRENGTHENING USING EXTERNALLY BONDED FIBER-REINFORCED POLYMER (FRP) COMPOSITE SYSTEMS (AC125)
V s V f 8 f c 'bwd
b
=
short side dimension of compression member of non-circular cross section, in. (mm).
bw =
web width or diameter of circular section, in. (mm).
d
distance from extreme compression fiber to centroid of tension reinforcement, in. (mm).
(23)
V s V f 0.66 f c 'bwd
(SI Units)
For rectangular sections with shear enhancement provided by transverse FRP composite material, section 3 corners must be rounded to a radius not less than /4 inch (20 mm) before placement of the FRP composite material.
=
CFRP = Carbon fiber reinforced polymer.
7.3.2.6.1
Rectangular Wall Sections: Nominal shear strength enhancement for rectangular wall sections of depth h parallel to the direction of applied shear force, with fiber thickness t f on both sides of the wall at an angle θ to the members’ axis, shall be given by
D
=
diameter of circular columns, inches (mm).
d b
=
reinforcement bar diameter, inches (mm).
d fv =
effective depth of FRP shear reinforcement, in (mm).
E c =
modulus of elasticity of concrete, psi (MPa).
E f =
modulus of elasticity of material, psi (MPa).
f j = 0.004 E j ≤0.75 f uj (for completely wrapped on all four sides).
E 2 =
slope of linear portion of stress-strain model for FRP-confined concrete, psi (MPa).
Where wall sections have fiber bonded to one side only at an angle ≥ 75 to the member axis, nominal shear strength enhancement shall be taken as
ΔF =
2
V sj = 2t f f j h sin θ
(24)
where
2
V sj = 0.75t j f j h sin θ
(25)
=
0.0015 E j ≤ 0.75 f uj .
Where wall sections have fiber bonded to one side at an angle ≥ 75 degrees to the member axis and with anchorage provided by bonding to the wall ends, the effective strain used to calculate f j shall be determined through full-scale structural testing. Shear Strength Reduction Factor: 7.3.2.6.2 Dependable shear strength enhancement shall be found by multiplying the nominal shear strength given by Equations (18), (24), or (25), as appropriate, by a shear strength reduction factor. Note: These provisions do not apply to shear strength enhancement provided by fiber that does not extend the full section width bonding to perpendicular faces (section ends). These provisions do not apply to shear strength enhancement for flanged sections requiring placement of fiber around re -entrant corners. These cases must be subject to special study. The use of special anchors attaching the FRP composite material at the wall edges may be effective in transferring the design fiber stress between wall or beam and fiber.
compressive stress in concrete, psi (MPa)
f’ c
=
specified compressive strength of concrete, psi (MPa).
f’ cc =
compressive strength of confined concrete, psi (MPa).
f fe
=
effective stress in the FRP; stress level attained at section failure, psi (MPa)
f ′m
=
specified compressive strength of masonry, psi (MPa).
f t′
=
tensile strength of concrete or masonry, psi (MPa).
f l
=
maximum confining pressure due to FRP jacket, psi (MPa).
f fe
=
effective stress in the FRP; stress level attained at section failure, psi (MPa).
f jf
=
confining strength of FRP composite material, (MPa).
f uj
=
ultimate tensile strength of composite material, (MPa).
f j
=
hoop stress developed in jacket material, (MPa).
GFRP = Glass fiber reinforced polymer.
Quality Control: The quality control documents described Sections 6.1 and 6.2 shall be submitted. Nomenclature:
Ac =
cross-sectional area of concrete 2 2 compression member, in (mm ).
Ae
cross-sectional area of effectively confined 2 2 concrete section, in (mm ).
=
2
increase in axial force, lb (N).
=
h
=
long side length of a rectangular column, inches (mm).
k 1
=
modification factor applied to v to account for concrete strength.
k 2 =
modification factor applied to v to account for wrapping scheme.
Le
=
active bond length of FRP laminate, in.
l s
=
reinforcement bar splice length, inches (mm).
=
perimeter of cracked surface, inches (mm).
7.4 7.5
composite
f c
where f j
FRP
in
2
Ag =
gross area of concrete section, in (mm ).
p
Afv =
area of FRP shear reinforcement with spacing 2 2 “s”, in (mm ).
pfm =
force per unit width that the FRP system transfers to the masonry substrate, lb/in (N/m)
psj =
volumetric ratio of retrofit jacket.
AFRP = Aramid fiber reinforced polymer 9
PROPOSED REVISIONS TO THE ACCEPTANCE CRITERIA FOR CONCRETE AND REINFORCED AND UNREINFORCED MASONRY
STRENGTHENING USING EXTERNALLY BONDED FIBER-REINFORCED POLYMER (FRP) COMPOSITE SYSTEMS (AC125)
M u =
bond strength between FRP composite material and concrete or masonry, psi (MPa).
n
=
number of plies of FRP reinforcement.
r
=
sf
=
radius of edges of a non-circular cross section confined with FRP, in. (mm).
efficiency factor equal to 0.55 for FRP strain to account for the difference between observed rupture strain in confinement and rupture strain determined from tensile tests.
μ
=
=
center-to-center spacing reinforcement, in (mm).
displacement ductility level, defined relative to yield or cracking displacement.
g
=
t f
=
effective FRP composite material thickness.
ratio of area of longitudinal steel reinforcement to cross-sectional area of a compression member.
V f
=
shear strength enhancement composite material, lb (N).
f
=
FRP strength reduction factor.
=
0.85 for flexure (calibrated based on design material properties).
=
0.85 for shear (based on reliability analysis) for three-sided FRP U-wrap or two-sided strengthening schemes.
=
0.95 for shear fully wrapped sections.
of
FRP
shear
provided by
V c =
nominal shear strength provided by concrete with steel flexural reinforcement, lb (N).
V s
nominal shear strength provided by steel stirrups, lb (N).
=
w f =
width of FRP reinforcing plies, in. (mm).
=
angle of fiber inclination to member axis, degrees.
εc
=
concrete compression strain.
εcc =
strain at peak stress for confined concrete.
εcu =
ultimate compression strain of unconfined concrete.
εccu =
ultimate compression concrete.
εf
=
strain composite strength.
εfe
=
effective strain level in FRP reinforcement attained at failure, in/in (mm/mm).
ε fd =
debonding strain of externally bonded FRP reinforcement.
strain
material
Referenced Documents 1)
of at
ACI Committee 440.2R-08, 2008, “Guide for the Design and Construction of Externally Bonded FRP Systems for Strengthening Concrete Structures,” American Concrete Institute, Farmington Hills, MI. 2)
Concrete Society, “Design Guidance for Strengthening Concrete Structures Using Fibre Composite Materials,” Technical Report No. 55 (TR55), second edition, Surrey, 2004.
confined designated
3)
Pessiki, S.; Harries, K. A.; Kestner, J.; Sause, R.; and Ricles, J. M., “The Axial Behavior of Concrete Confined with Fiber Reinforced Composite Jackets,” Journal of Composites in Construction, ASCE, V. 5, No. 4, 2001, pp. 237-245. 4)
fu
=
ultimate strain of FRP composite material.
’t
=
transition strain in stress-strain curve of FRPconfined concrete, in/in (mm/mm)
=
strength reduction factor.
a
=
efficiency factor for FRP reinforcement in determination of f’ cc (based on geometry of cross section).
Priestley, M.J. Nigel, Frieder Seible and Michele Calvi, Seismic Design and Retrofit of Bridges (Chapters 1 through 8). John Wiley and Sons, Inc., New York, September 1995, 672 pp. 5)
b
=
efficiency factor for FRP reinforcement in determination of ccu (based on geometry of cross section).
v
=
bond-dependent coefficient for shear.
Lam, L., and Teng, J., “Design-Oriented Stress-Strain Model for FRP-Confined Concrete,” Construction and Building Materials, V. 17, 2003a, pp. 471 -489. 6)
Lam, L., and Teng, J., “Design -Oriented Stress-Strain Model for FRP-Confined Concrete in Rectangular Columns,” Journal of Reinforced Plastics and Composites, V. 22, No. 13, 2003b, pp. 1149-1186. 7)
NSF 61-2003e, Drinking Water Components—Health Effects, NSF International. ■
TABLE 1—CREEP RUPTURE AND FATIGUE STRESS LIMITS IN FRP REINFORCEMENT
PARAMETER
Fiber Type
Stress Type
GFRP
AFRP
CFRP
Creep Rupture
0.20f uj
0.30f uj
0.55f uj
10
PROPOSED REVISIONS TO THE ACCEPTANCE CRITERIA FOR CONCRETE AND REINFORCED AND UNREINFORCED MASONRY
STRENGTHENING USING EXTERNALLY BONDED FIBER-REINFORCED POLYMER (FRP) COMPOSITE SYSTEMS (AC125)
TABLE 2—PHYSICAL PROPERTIES
6
PROPERTY
TEST METHOD
Tensile strength
ASTM D3039
Elongation
ASTM D3039
Tensile modulus
ASTM D3039
Coefficient of thermal expansion (CTE)
ASTM D696 or ASTM E831
8
NO. OF SPECIMENS 2
20
3
Creep
ASTM D2990
Void content
ASTM D2584 or D3171
4
9
1
4
5
2
5
2
5
Glass transition (Tg) temperature
ASTM D4065 E1640 or ASTM E831
Composite interlaminar shear strength
ASTM D2344
7
20
5
20
1
Specimen sets shall exhibit a coefficient of variation (COV) of 6 percent or less. Outliers are subject to further in vestigation according to ASTM E178. If the COV exceeds 6 percent, the number of specimens shall be doubled. 2 Values shall be determined in the primary and cross (90 ) directions. 3 Test duration is 3,000 hours, minimum. 4 Maximum void content by volume is 6 percent. 5 Minimum 140 F (60 C) Tg is required for control and exposed specimens. 6 For terminology, ASTM E1142 is a reference. 7 When using ASTM E831, an Expansion versus Temperature curve as shown in Figure 1 of ASTM E831 shall be developed; two tangents to the curve shall be plotted to coincide with the straightline portions of the curve above and below the inflection point. The point of intersection of these tangents shall be reported as Tg for the material. 8 Creep stresses for design shall be the lesser of the analysis of test or the maximum values in Table 1. 9 Tg under ASTM E1640 should be established using the Loss Modulus procedure. °
°
°
TABLE 3—ENVIRONMENTAL DURABILITY TEST MATRIX PERCENT RETENTION ENVIRONMENTAL DURABILITY TEST
ASTM D2247
Water resistance
ASTM E104 ASTM D1141 ASTM C581
Saltwater resistance Alkali resistance
ASTM C581
Dry heat resistance °
RELEVANT SPECIFICATIONS
ASTM D3045
TEST CONDITIONS
°
100 percent, 100 ± 2 F °
Immersion at 73 ± 2 F Immersion in Ca (CO 3) °
at pH = 9.5 & 73 ± 3 F
TEST DURATION
1,000 and 3,000 and 10,000 hours 1,000 and 3,000 hours
°
For SI: C= (t F – 32)/1.8.
FIGURE 1—STRESS-STRAIN DIAGRAM FOR FRP-CONFINED CONCRETE 11
1,000
3,000
90
85
1,000 and 3,000 and 10,000 hours
1,000 and 3,000 hours
°
140 ± 5 F
Hours
PROPOSED REVISIONS TO THE ACCEPTANCE CRITERIA FOR CONCRETE AND REINFORCED AND UNREINFORCED MASONRY
STRENGTHENING USING EXTERNALLY BONDED FIBER-REINFORCED POLYMER (FRP) COMPOSITE SYSTEMS (AC125)
FIGURE 2—EQUIVALENT CIRCULAR CROSSSECTION
FIGURE 3—TEST SEQUENCE OF IMPOSED DISPLACEMENT
12
