TMS 402/602 COMMITTEE PRESTRESSED SUBCOMMITTEE. Agenda

Transcription

1 CHAIR JOHN CHRYSLER VICE-CHAIR DAVE PIERSON 2 ND VIICE-CHAIR DICK BENNETT SECRETARY ANDY DALRYMPLE SUBCOMMITTEES CONSTRUCTION REQUIREMENTS JONATHON MERK TMS 402/602 COMMITTEE PRESTRESSED SUBCOMMITTEE SUBCOMMITTEE CHAIR Arturo Schultz University of Minnesota 500 Pillsbury Dr. SE Minneapolis, MN (612) aeschultz@umn.edu MOHAMED ELGAWADY MISSOURI UNIVERSITY OF SCIENCE & TECHNOLOGY 1401 N. Pine St. Rolla, MO (573) elgawadym@mst.edu SUBCOMMITTEE SECRETARY STAFF CONTACT, TMS, PHILLIP J. SAMBLANET, (303) , PSAMBLANET@MASONRYSOCIETY.ORG DESIGN MARK McGINLEY FORM & STYLE JAMES FARNY EMPIRICAL JASON THOMPSON GENERAL REQUIREMENTS DIANE THROOP PARTITION & INFILLS CHARLES TUCKER PRESTRESSED MASONRY ARTURO SCHULTZ REINFORCEMENT & CONNECTORS ROCHELLE JAFFE SEISMIC & LIMIT DESIGN JOHN HOCHWALT April 7, :45 11:30 AM Riverside II Room Hampton Inn New Orleans New Orleans, LA 1. Call to Order 2. Antitrust Statement 3. Approval of Agenda Agenda STRUCTURAL MEMBERS FERNANDO FONSECA VENEER & GLASS BLOCK BRIAN TRIMBLE 4. Review of Subcommittee Roster Voting Membership Arturo Schultz, Chair Mohamed ElGawady, Secretary David Biggs Jennifer Bean Popehn Paul Scott Khaled Nahlawi Ed Freyermuth Asok Ghosh Michael Merrigan Corresponding Members Russ Brown Trey Hamilton Dave Woodham Guilherme Parsekian Jenny Tanner Eisenhauer 5. Approval of Minutes 6. Announcements 6.1 Voting on Ballots Ballot 7 Items Due: May 4, 2018 THE MASONRY SOCIETY PAGE! OF! 1 6 TMS _Agenda_2018 Spring Meeting_PR.docx

2 Ballot Opens: May 12, 2018 Ballot Closes: June 10, 2018 Ballot 8 Items Due: July 20, 2018 Ballot Opens: July 28, 2018 Ballot Closes: August 26, Calendar Working Draft: October 2017 (upcoming April 20, 2018) 2018 Annual Meeting Cleveland, OH October 3-6, Holdover TAC Comments 7.1 TAC Comments from 2013 Cycle (2013) TAC Comment 201 TAC Comment: This is confusing to refer to two different editions of ASCE 7 (two different tables from two different editions of ASCE 7) are referred to), particularly when neither is listed in the references at the end of the Code. Revise for clarity. Same issue on Line 60 of the commentary as well. Subcommittee Action: Two more ballots are needed to fully clean up this item. Ballot 07-PR-001 Rationale: Main Ballot 05-PR-001 concerning 2013 TAC comment 201 passed with no negatives. There was one Affirmative with Comment vote from Benson Shing who suggests that the phrase "seismic design criteria proposed by Hassanli" be changed to seismic design factors proposed by Hassanli" in TMS 402 Commentary sections and The Subcommittee agrees with Shing s comment. Proposed Changes: Code: (None) Code Commentary: : To utilize the seismic design criteria factors proposed by Hassanli et al. (2015), the structure would have to be accepted under Section 1.3, Alternative design or method of construction : To utilize the seismic design criteria factors proposed by Hassanli et al. (2015), the structure would have to be accepted under Section 1.3, Alternative design or method of construction. Ballot 7-PR-002 Rationale: THE MASONRY SOCIETY PAGE! OF! 2 6

3 Main Ballot 05-PR-001 concerning 2013 TAC comment 201 was prepared to eliminate references to older versions of ASCE 7 and the IBC. The ballot passed with no negatives. However, one of the IBC was not removed. Proposed Changes: Code: (None) Code Commentary: : The seismic coefficients from IBC 2003, Table and the building height limitations based upon seismic design category are shown in Table CC TAC Comments from 2016 Cycle-None 8. Holdover Public Comments 8.1 Public Comments from 2013 Cycle-None 8.2 Public Comments from 2016 Cycle-None 9. Horizontal Prestressing A revision to Chapter 10 was prepared by David Biggs in the previous Code Cycle and has been subsequently been updated. Biggs noted that the intent of this change is to allow for the use of prestressed beams, lintels and slabs, and not for horizontal prestressing in shear walls. Biggs noted that beams and lintels are to be solid, but slabs can be partially grouted. The revised TMS 402 Chapter 10 was sent as a ballot to the Subcommittee. The votes were 5 Affirmative, 3 Affirmative with Comment, and 1 member did not vote. Nahlawi Comments: Name Page Line A/C/N Comment KN C st paragraph A/C The study is limited to few test samples. The last paragraph in the conclusion states; However, further research and analysis with experimental and theoretical studies is required to assess the effect of masonry strength, tendon eccentricity and initial prestress on the structural performance of this type of elements. C start A Agree with changing walls to members end A Deleting beams, and lintels nd A Added walls ungrouted masonry walls rd A.. prestressed masonry walls members th T A within a wall member th E A has indicated that for walls prestress THE MASONRY SOCIETY PAGE! OF! 3 6

4 C A/C For clarification, suggest to revise to read: Therefore, the ends of masonry beams and lintels must be solid and reinforced to distribute the anchorage of the tendons into the masonry. C A Agree with changes: Design methods are now based upon strength provisions with serviceability checks based upon allowable stress level requirements. A masonry wall member is typically prestressed prior to 28 days after construction, sometimes within C A/C (ACI 318, 2014z) what does z stand for? C A estimates for typical wall applications, unless C A The requirements for prestressed masonry walls members subjected to axial compression and flexure are separated into those with laterally unrestrained prestressing tendons and those with laterally restrained prestressing tendons. This separation was necessary because the flexural behavior of a prestressed masonry wall member significantly depends upon the lateral restraint of the prestressing tendon. Lateral C A of prestressing force to the masonry wall member and stresses C A prestressed masonry walls members, the prestressing force C st A moment strength of prestressed masonry walls members is C st E C What is the change? Not obvious to me. C AC Previously walls were changed to members. Here code side, walls were kept? For the commentary side should walls be changed to members This section was moved from TMS -16 C N Delete section and change to read: For members or list the members and the reference in the commentary C A Added subheading C A Changed table header to read walls and not members C A The whole section is marked, however, only the end paragraph was added to the commentary. The added paragraph is acceptable. C-159 Section 10.6 new C-161 A The shear strength of prestressed walls members is A For walls members with bonded C-161 A that prestressed masonry walls members are reinforced, for walls members without bonded mild reinforcement, C A for prestressed masonry walls members C A accessories is required in masonry walls members Popehn Comments: * Pg C-151: first paragraph added to commentary - move to appropriate location below 10.1 Header * Commentary First paragraph - suggest keeping applicable language of deleted sentence This chapter applies to... * Commentary Suggest adding a reference to Hamilton & Stierwalt paper on what constitutes a restraint THE MASONRY SOCIETY PAGE! OF! 4 6

5 * Code Sections Look at reorganizing sections to have similar member sections adjacent to one another. It currently jumps back and forth between types. * Code section Italicize Pps and P in newly added text. * Code section - to be consistent with and , add italic text Calculation of fps for beams, lintels, slabs * Commentary new text starting Table italicize d before distance. Merrigan Comments: *Commentary reference to Section should actually be *Commentary reference to Section should actually be All corrections and suggestions made by Bean Popehn and Merrigan were made, as well as the corrections suggested by Nahlawi except for the 1 st, 8 th, 17 th and 18 th comments. The following responses are offered: 1 st Comment (in reference to the first paragraph of Chapter 10): The study is limited to few test samples. The last paragraph in the conclusion states; However, further research and analysis with experimental and theoretical studies is required to assess the effect of masonry strength, tendon eccentricity and initial prestress on the structural performance of this type of elements. The referenced paper actually addresses the effects of these three variables in a comprehensive treatment. 8 th Comment (in reference to section ): For clarification, suggest to revise to read: Therefore, the ends of masonry beams and lintels must be solid and reinforced to distribute the anchorage of the tendons into the masonry. The suggested comment does not apply to slabs that can be partially grouted, thus tendon lateral restraint is the common requirement. 17 th Comment (in reference section ): Previously walls were changed to members. Here (on the) code side, walls were kept? Yes, because section is for out-of-plane walls, section is for shear (in-plane) walls, and section is for beams, lintels and slabs. The title for the last section ( ) has been highlighted (as suggested by Bean Popehn) to make this subdivision clear. 18 th Comment (in reference to ): Delete section and change to read: For members or list the members and the reference in the commentary. Section is for out-of-plane walls, section is for shear (in-plane) walls, and section is for beams, lintels and slabs. The title for the last section ( ) has been highlighted (as suggested by Bean Popehn) to make this subdivision clear. Chair Schultz will prepare a single item regarding all changes for horizontal prestressing for an upcoming TMS 402 ballot. 10. Strength Reduction Factor (φ) for Axial Loads Ballot 7-PR-004 Rationale: The formulas specified in Chapter 10 of the TMS 402 Code for the calculation of the flexural strength of masonry members was modified in the 2016 Code Cycle to introduce the strength reduction factor (φ) for the axial load contribution to masonry compressive stress (Pu/φ). However, a value for the strength reduction factor for axial loading in prestressed masonry was not defined in Chapter 10. The ballot proposes using the same strength reduction factor for axial loading in prestressed masonry that is used for flexure (φ = 0.8). This is the same procedure that is used for reinforced masonry, even though a smaller value is proposed for prestressed masonry. THE MASONRY SOCIETY PAGE! OF! 5 6

6 Proposed Changes: Code: The design moment strength shall be taken as the nominal moment strength, Mn, multiplied by a strength reduction factor (φ) of 0.8. The value of φ shall also be taken as 0.8 for axial load. Code Commentary: The same value for the strength reduction factor that is used for flexure (φ = 0.8) is used for axial loading in prestressed masonry. This is the same procedure that is used for reinforced masonry in Chapter 9, but a lower value is used for prestressed masonry. 11. New Code Change Issues/Proposals 11.1 Seismic Coefficients 11.2 Prestressed Masonry Bibliography 11.3 MDG Updates 11.4 Post-tensioning as temporary bracing during masonry construction 11.5 Post-tensioning in shipping/handling of pre-fabricated masonry members 11.6 Check shear stress transfer across thinner webs (now ¾" from 1" previously) 11.7 Other type of pre-stressed walls, such as special pre-stressed masonry shear wall 11.8 Losses 11.9 Outreach and education on Prestressed Masonry to engineers, architects, contractors, masons and others 12. Seismic Coefficients for Prestressed Masonry Task Group Report (Elgawady) 13. Tendon Stress Formula for Prestressed Shear Walls (Elgawady) 14. New Business 14.1 Prestressed Masonry session proposal(s) for 13 th NAMC (Salt Lake City 2019) 15. Next Meeting Date 2018 Annual Meeting in Cleveland, OH, October 3-6, Adjournment THE MASONRY SOCIETY PAGE! OF! 6 6