aci committee 369 - american concrete institute

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ACI COMMITTEE 369 SEISMIC REPAIR AND REHABILITATION

2015 ACI Spring Convention Kansas City, MO

April 13, 2015

2:00 p.m.– 6:00 pm Meeting Minutes – Meeting 3

Members Present: See Appendix 1.

Visitors: See Appendix 1.

1. Welcome and introductions Wassim Ghannoum welcomed the audience, and reviewed the agenda.

2. Approval of Meeting Agenda Moved: Adolfo Matamoros; Second: Jeff Dragovich.

3. Approval of Minutes from Spring Meeting Minutes from the 2014 Fall meeting in Washington DC were approved as presented (posted on committee

webpage).

Moved: McCabe; Second: Dragovich; Abstain: Kenneth Luttrell

4. Update Wassim Ghannoum discussed the 8 substantial technical changes that the committee is planning to pursue

during the summer 2015. Each technical change will be investigated by a separate group. Ghannoum

encouraged committee members to contribute to at least one technical change.

5. ACI 369 and ACI 440 Collaboration In the last meeting, ACI 440 proposed a seismic chapter that some of the ACI 369 committee members

reviewed. The committee members agreed that ACI 369 committee should continue working with ACI

440 to assure that our documents will work well together. Moreover ASCE/SEI41 needs to propose tables

for m-factors and modeling parameters of retrofitted members, emphasizing the need for collaboration

between ACI 440 and ACI 369 committees.

6. ACI 369 and ACI 562 Collaboration Jim Stevens gave a presentation about ACI 562 activities to find the opportunities for collaboration

between ACI 369 and ACI 562. ACI 562 is writing a code document that will be published next year.

This building code will be similar to ACI 318, but for existing buildings, and is aimed to be used as a

standalone provision that also works well with the IEBC. Since both ACI 369 and 562 deal with existing

buildings, these documents need to be consistent. Stevens suggested forming a committee from members

of both committees to work on mutual topics and provide a list of items and goals for collaboration.

7. Task Groups for Technical Changes Wassim Ghannoum talked about the subcommittees for 8 technical changes that the ACI 369 committee

will make over the next summer. Four main task groups are already formed (See Appendix 2). Wassim

Ghannoum asked the committee members to sign up for at least one group. Most of the technical changes

will be balloted before August 2014. The first iteration of comments from balloting process will be

discussed in the summer meeting. The technical changes will be reballoted after the summer meeting, and

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the remaining issues will be resolved at the November convention. Further discussions were made on the

following technical changes:

7.1. Moment Frame Task Group: Update the Modeling Parameters of Beams

Adolfo Matamoros reviewed the beam proposal. He noted that the current beam modeling

parameters in ASCE/SEI 41 are from FEMA 356, and in contrast to columns, have not been

updated for a long time. His task group will develop new tables for nonlinear modeling

parameters and acceptance criteria of beams.

The ballot did not pass due to insufficient votes. Proposed resolution to negative votes are

presented in Appendix 3.

7.2. General Provisions Task Group

Insung Kim reviewed the future proposed changes, as follows:

- Minimum testing requirements for anchors: ASCE 41 does not have minimum testing

requirements for anchors. This issue may become a concern for wall-to-diaphragm anchors in

existing buildings, as they may be in the load path of the structure, and currently there is no

quality control for these components. As a result, ACI 369 needs to develop a set of minimum

testing requirements for the anchors.

- Tension in columns and walls: Please see the discussion in the minutes from the ACI 369 meeting

on 04/12/15 (first day of the convention).

7.3. Shear Walls Task Group

- Stiffness of the walls: Garret Hagen was selected to form a team to investigate various approaches

to compute the flexural stiffness of the wall.

- Modeling Parameters and Acceptance Criteria of slender walls: Anna Birely will update the

tables for modeling parameters and acceptance criteria of slender walls. Her group will also

clarify the use of shear controlled versus flexure controlled walls. Moreover, the m-factors of the

shear controlled walls will be updated.

7.4. Retrofit Techniques Task Group

- Developing tables for Modeling Parameters and Acceptance Criteria of jacketed columns: Sergio

Breña will develop a set of tables for modeling parameters and acceptance criteria of rectangular

and circular jacketed columns based on his ongoing work with his Ph.D. student.

Break (20 minutes)

During the break committee members signed up to participate in at least one task group (See Appendix 2).

The meeting was reinitiated at 4:30 p.m.

8. Reviewing Ballots on the Wall Sections Anna Birely reviewed the balloting results on the wall section and discussed a few negative votes on

the usage of the word “measured” material properties and notations used in the wall section.

The ballot did not pass due to insufficient votes. Proposed resolution to negative votes are

presented in Appendix 4 and Appendix 5.

9. Reviewing Ballots on the General Provision and Notation Sections Adolfo Matamoros reviewed the balloting results on the general provisions for the frame section. Most of

the comments and changes were on the clarification of parameters used in ASCE/SEI 41. The ballot did

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not pass due to insufficient votes. Proposed resolution to negative votes are presented in

Appendix 6. There was further discussion regarding the clarification needed on the parameters used in the computation

of strength. The main focus was on distinguishing between the expected and lower bound material

properties in classification and strength determination of columns. Several options were discussed to

address this issue as outlined in the minutes of the April 12 committee meeting.

The ballot for the notations did not pass due to insufficient votes (see Appendix 7). The change

proposal will not be re-balloted again. Notations will be handled in each subsequent ballot

separately.

10. Summer Meeting First and second week of August were chosen for scheduling the summer meeting. The location of the

meeting will be determined later.

11. Adjournment Moved: Izquierdo; Second: Breña.

Minutes respectfully submitted by: Siamak Sattar.

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Appendix 1: List of Attendees on 04/13/2015 Meeting

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Appendix 2: List of Task Groups and Change Proposal Groups

1 2 3 4 1 2 3 4 5 6 7 8

General Frames Walls Retrofit Columns Beams Joints Anchors Tension wall stiff wall MP Retrofit

Wassim Ghannoum x x x x x x

Siamak Sattar x x x

TAC Contact

Andrew Taylor

Anna Birely O x x

Sergio Brena O x

Casey Champion x x x

Jeffrey Dragovich x

Kenneth Elwood x x

Una Gilmartin x x

Arne Halterman x x x

Wael Hassan x x x x

Mohammad Iqbal x

Jose Izquierdo-Encarnacion x x

Afshar Jalalian x

Thomas Kang x

Dominic Kelly*

Insung Kim O x x x

Laura Lowes x x x x x

Kenneth Luttrell x x

Adolfo Matamoros O x x

Steven McCabe x x

Murat Melek x x

Jack Moehle

Arif Ozkan x x x

Robert Pekelnicky x x

Jose Pincheira x x x

Mario Rodriguez*

Murat Saatcioglu*

Halil Sezen x x x x

Roberto Stark x x x x

Andreas Stavridis*

John Wallace x x

Tom Xia x x x x

Sergio Alcocer

David Bonowitz

Charles Hookham

Shyh-Jiann Hwang

Regan Milam

Andrew Mitchell

Raj Valluvan

Dave Beh

Thomas Bush

Julian Carrillo

Sushil Chauhan

Methee Chiewanichakorn

C Terry Dooley

Anindya Dutta

Simon Foo

Sigmund Freeman

Juan Fuentes

Aysegul Gogus

Garrett Hagen x

Consulting Members

Associate Members

Task Group Change Proposal

Voting Members

Officers

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John (Jack) Hayes

Guillermo Huaco-Cardenas

Mohammad Jalalpour

Brian Knight

Hung-Jen Lee

Andres Lepage

Gang Lu

Leonardo Massone

Yi-Lung Mo

Abbas Mokhtar-Zadeh

Mark Moore

Vilas Mujumdar

Aniruddha Nakhawa x x

Sarah Orton

Dan Palermo

Owen Rosenboom

David Sanders

Mehrdad Sasani

Drit Sokoli

Ying Tian

Michael Valley

John Viise

Jacqueline Vinkler

Ashkan Vosooghi

Travis Welt

Sarah Witt

Meagan Young

Kumars Zandparsa *The committee member has not expressed the areas where he will participate.

Note: Symbol “o” shows the leader of the task group.

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Appendix 3: Resolutions to Ballot Comments and Negatives (CH.17)

Last Name

Item No.

Page No.

Line No. N,

A/C Voter Comment Resolution / Vote Count

1. Kim CH17 103-107 C

Mnc_exp and Mnb_exp

should be defined in Ch.

14 (notations) as well

Noted

2. Kim CH17 General C

ASCE 41 does not use

nominal capacities with

subscript of “n” (e.g. Vn

or Mn) or factored design

forces with subscript of

“u” (Vu, Mu or Nu).

Subscripts “CE” & “CL”

are used for capacity side

and “UD”& “UF” for

demand side.

Subscripts should

correspond to the ASCE

41. For example, Vn,exp

should be VCE.

Changed: CE Capacity based on expected material properties, CL Capacity based on lower Bound, UD Deformation controlled actions), UF force controlled actions

3. Kim CH17 355-356 N

Is “fc’ str” lower bound

or expected strength?

Clarification should be

provided.

Notation changed to fc’,C and clarification added

4. Brena CH17 9 249-250 N

In the following

sentence, the limits

coll,

not ap.

“The database used to

assess the probability of

failure for parameter bp

includes columns with ap

≤ 33. Use caution when

applying the values from

Table 12 to columns with

ap > 33.”

corrected

5. Brena CH17 11 304 N

The reference in the

sentence should be to Eq.

4 instead of Eq. 3

corrected

6. Brena CH17 23 655-658 N

The current definintion

of Vc exp in the standard

does not include

punching strength of

slabs. This section refers

to the punching strength

Notation changed in the document to address Vo and shear strength.

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Last Name

Item No.

Page No.

Line No. N,


of slab-column

connections. Either a

different notation should

be used here or the

definition expanded to

include punching shear

strength of slab-column

connections (ACI 318

Section 22.6.5). Is it Vo,

exp? (see notation)

7. McCabe 6 175-184

Both places refer to

added equations and

terms:

The term Nu is taken

from ASCE 41 and is

based on expected axial

loadings. While this term

does match that found

ASCE 41 it can be

confused with the ACI

318 term, which is based

on fully factored design

loads. This seems to be

potentially confusing. Is

this correct as stated?

Perhaps a change in

subscript might be in

order?

The terms Mu/Vud is

proposed which appears

to be the fully factored

moment and shear design

values, if one applies

ACI 318. However,

ASCE 41 is based on

expected loadings and

uses M/Vd without the

subscript u. This is

inconsistent in my

opinion and potentially

confusing.

Notation changed

8. McCabe 10 302-311 Same as above Notation changed

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Last Name

Item No.

Page No.

Line No. N,


9. Ghannou

m CH17 4 103-107 C

Change notation to Mnce and Mnbe to be consistant with notation elsewhere such as Fye and FyL

Notation changed

10. 6

145-6 159 162

165-7, 172 …

C Change notation to Vne, Vpe

Notation changed

11. 7 174 N

I prefer to have the equation not in commentary but in the body of the code along with definitions. Perhaps equation 4 and 3 can be merged into one. with a general Vn equation then Vne= Vn with expected material properties, VnL = Vn with lower bound material properties. Specify VnL for force controlled, Vne for deformation controlled I agree with allowing ACI 318 shear strength equation ot be used (line 190) it should be kept in the re-organization. Change other term subscripts accordingly.

Equation was moved to the code as suggested. Changes were made to the notation to address comments about expected and lower bound material properties.

12. 6 146 N

Vpe should be defined better. This is suggested: … “shear demand at the expected flexural strength of plastic hinges…” in the commentary one should add that using ACI 318 1.25fyL approach is valid. In the notation section the definition should also

Prefer to leave it as is but open for discussion. With the changes made, the calculation of Vp, now defined as VUF, will be made on the basis of expected material properties.

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Last Name

Item No.

Page No.

Line No. N,


reflect this and specify that hardening should be accounted for.

13. 174 C F’ce instead of f’c,exp Notation changed

14. C F’c,str should be f’cL (lower bound)

Notation changed

15. Rodrigue

z 6 160

The condition of shears in line 160 page 6 seems need an upper limit and isn't this condition similar to the one shown in line 163. Please clarify. The documents should show the background of Equation 3 for shear strength including a comparison or predicted and measured shear strength in tests of RC columns. How the reader decides using either Eq 3 or the shear strength equation given by ACI 318 Chapter 18?

Clarification was added. The information requested is provided in the reference cited. The use of ACI 318 equations was clarified.

16. 219

Regarding the probability of failure Pf mentioned in line 219 how the document shows that this is a reliable figure for Pf?

This information was published in a paper in earthquake spectra and a peer report. Those are cited in the document

17.

Why the numbering of Eqs using letter-number C1 and C2 in page 9 when previous equation are referred to numbers? Why Table C1 and not Table 23?

The notation C is intended to refer to the commentary. Equation 3 was moved from the commentary to the main text in response to another reviewer comment so now the numbering is consistent.

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No.

Last Name

Item No.

Page No.

Line No.

N, A/C

12. Comment 13. Response

18. Kim CH18 100 N

“ or measured” should be deleted. By

definition (ASCE41-13, 7.5.1.4),

expected strength is the mean of

measured values from the material tests

(Or default LB or nominal strength x

multiplier).

Agreed. “or measured”

19. Brena CH18 8 158 A/C “of 0.5 times the … Agreed and revised

per comment.

20. Brena CH18 9 159 N

Coordination with other chapters is needed to use the same notation for modeling parameters (a, b, c). The moment frame chapter uses ap, bp to refer to points in the nonlinear backbone curve to distinguish these parameters from the a and b used in ACI 318. We need to be consistent.

Agreed. Subscripts nl have been added to the modeling parameters

21. Brena CH18 9 170 N

See comment above. There will be a notation conflict with the definition of d in ACI 318. Should be dp, but this is used for prestressed concrete beams in ACI318. This also affects the notation chapter.


22. Brena CH18 15 308 A/C Replace shear wall with structural wall. Agreed and revised per comment.

23. Rodrigu

ez CH18 165 A/C

Regarding lp in line 165 some wording is needed advising the reader that the suggested values might be gross measures of this parameter.

Will be addressed in future ballot addressing revision of modeling parameters.

24. Rodriqu

ez CH18 15 299 A/C

Regarding wall boundary elements in line 299 the wording "elements may be an effective measure..." should read "elements is an effective measure..." The reason is that this document should emphasize on the importance of using wall boundary elements for a significant improvement of a wall's seismic response.

The language "may be" is consistent between all suggested retrofit measures. Consistency should also be maintained with other chapters. No changes have been made.

25.

Huaco-Cardenas Guillermo D

CH18 non

voting

The inclusion of FEMA 440 (2005) - Improvement of Nonlinear Static Seismic Analysis Procedures would be a good reference to be used specially for 7.2.2.2 Nonlinear Static and 7.2.2.3 Nonlinear Dynamic Procedure.

Will be addressed in future ballot addressing revision of modeling parameters.

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No.

Last Name

Item No. Page No.

Line No.

N, A/C 14. Comment 15. Response

26. Brena CH19 7 119, 121

N

Coordination with other chapters is needed to use the same notation for modeling parameters (a, b, c). The moment frame chapter uses ap, bp to refer to points in the nonlinear backbone curve to distinguish these parameters from the a and b used in ACI 318. We need to be consistent.


27. Brena CH19 7 124, 126

N

There will be a notation conflict with the definition of d in ACI 318. Need to find a new way to define d for the backbone curves. The notation chapter uses dp, but this will conflict with the effective depth of prestressing reinforcement in ACI 318.


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No. Last Name Item No.

Page No.

Line No.

N, A/C

16. Voter Comment Resolution / Vote Count

1. Kelly CH16

19 12

A/C

I recommend eliminating “as well as chemical bond.” ACI 408 indicates that bar slip eliminates the chemical bond before the mechanical bond is engaged. Therefore, current equations are only accounting for mechanical bond.

Agreed. (update required.)

2. Rodriguez CH16

13 20

C

References in this section for combined strength under uniaxial or biaxial bending with axial load need to be updated. Restrepo et al. (2013) have proposed a simple procedure for computing the probable moment strength of rectangular and circular columns for both uniaxial and biaxial bending with axial load. Restrepo J., and Rodriguez, M., (2013),“On the Probable Moment Strength or RC Columns”, ACI Structural Journal, V. 110, No. 4

Please provide task group/ committee change proposal. Future work. Mario to submit change proposal

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Page No. Line No.

N, A/C

17. Comment

3. Ghannoum CH20

89 C Should add a definition for - Expected Material

Properties: material properties obtained in accordance with Section 2.2.

4. Ghannoum

C If the above definition is added remove “or

measured” in Vce, Vne, Vpe, etc

5. Ghannoum CH20

C Make sure to update notations as per other

chapter changes due to ballot responses

6. Ghannoum CH20 C F’c,lb should be f’cL

7.

Ghannoum

CH20

C

Definition of m, add at the end: “m-factors are provided in tables providing numerical acceptance criteria for linear procedures for various members”

8. Ghannoum CH20 N Definition of my: remove Eq1.

9. Ghannoum

CH20 C Definition of k (kappa): add at the end: “, ASCE

41 Sections 5.2.6 and 6.2.4.”

10.

11. Kim CH17 103-

107 C

Mnc_exp and Mnb_exp should be defined in

Ch. 14 (notations) as well

12. KIM CH

20 N Section 14.2

Mnc_exp and Mnb_exp should be defined.

13.

KIM CH

20

N

Section 14.2

“ or measured” should be deleted in the

definitions of all the expected material strengths.

By definition (ASCE41-13, 7.5.1.4), expected

strength is the mean of measured values from

the material tests (Or default LB or nominal

strength x multiplier).

14. KIM CH

20 N Section 14.2

Is “fc’ str” lower bound or expected strength?

Clarification should be provided.

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Ghannoum CH20 89 C Should add a definition for - Expected Material Properties: material properties obtained in accordance with Section 2.2.

51 C If the above definition is added remove “or measured” in Vce, Vne, Vpe, etc

52 C Make sure to update notations as per other chapter changes due to ballot responses

53 C F’c,lb should be f’cL

54 C Definition of m, add at the end: “m-factors are provided in tables providing numerical acceptance criteria for linear procedures for

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Page No. Line No.

N, A/C

17. Comment

various members”

55 N Definition of my: remove Eq1.

56 C Definition of k (kappa): add at the end: “, ASCE 41 Sections 5.2.6 and 6.2.4.”

57 C

Definition of m, add at the end: “m-factors are provided in tables providing numerical acceptance criteria for linear procedures for various members”

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