NATIONAL »U*»AU

OF 8TAWPABD®

LIPKART MAY 1 8 1981

NBSIR 80-2111-6

REVIEW AND REFINEMENT OF ATC 3-06 TENTATIVE SEISMIC PROVISIONS

REPORT OF TECHNICAL COMMITTEE 6: STEEL

Mr. Jerry Iffland, Chairman, American Society of Civil Engineers

Dr. H. S. Lew, Secretariat, National Bureau of Standards

William A. Milek, American Institute of Steel Construction

Dr. Albert L. Johnson, American Iron and Steel Institute

Mr. John B. Scalzi, Interagency Committee on Seismic Safety in Construction

Mr. William A. Sontag, Metal Building Manufacturers Association

Mr. Norman K. Cohn, Steel Plate Fabricators Association

Mr. Clarkson Pinkham, Applied Technology Council

Mr. Charles De Maria, Building Seismic Safety Council

Prepared for use by the:

BUILDING SEISMIC SAFETY COUNCIL

Sponsored by:

FEDERAL EMERGENCY MANAGEMENT AGENCY

Center for Building Technology

National Bureau of Standards

Washington, D.C. 20234

October 1980

U.S. DEPARTMENT OF COMMERCE, Phillip M. Klutznick, Secretary

Luther H. Hodges, Jr., Deputy Secretary

Jordan J. Baruch, Assistant Secretary for Productivity, Technology,

and Innovation

National Bureau of Standards, Ernest Ambler, Director
• iW^>i c O r

|
Abstract

The Tentative Provisions for the Development of Seismic Regulations for

Buildings were developed by the Applied Technology Council to present,

in one comprehensive document, current state-of-knowledge pertaining

to seismic engineering of buildings. The Tentative Provisions are in

the process of beign assessed by the building community. This report

is one of a series of reports that documents the deliberations of a group of professionals jointly selected by the Building Seismic Safety

Council and the National Bureau of Standards and charged with reviewing

the Tentative Provisions prior to the conduct of trial designs. The

report contains the recommendations and records of the committee

charged with review of the steel design provisions. The committee

made 6 recommendations for revisions to the Tentative Provisions

and three additional recommendations. These recommendations were

made to the parent group, the Joint Committee on Review and Refinement,

and their action on these recommendations is documented in a companion

report

Key Words: Building; building codes; building design; earthquakes;

engineering; standards; steel; structural engineering.

iii
TABLE OF CONTENTS

Page

1.0 INTRODUCTION

1.1 General 1 1*2 Committee Summary 1

2.0 COMMITTEE ACTIONS 4

2.1 Recommendations for Change 5 2.2 Recommendations for Trial Design 11

3.0 COMMITTEE RECORDS 12

3.1 Minutes of Meeting 12

3.2 Committee Roster 21

3.3 Selected Committee Correspondence and Applied Technology

Council Comments 24

iv
1.0

INTRODUCTION

1.1 General

The Tentative Provisions for the Development of Seismic Regulations were developed by the Applied Technology Council (ATC) in an effort that included

a wide range of experts in the actual drafting of the provisions. Two

external review drafts were circulated to a large portion of the interested

and informed community of eventual users. However, because the Tentative

Provisions were innovative, doubts about them existed. Consequently, an attempt was made to investigate these doubts and to improve the Tentative

Provisions where possible before an expensive assessment of the Tentative

Provisions was undertaken by conducting trial designs.

This review and refinement project was planned and conducted by the National

Bureau of Standards with the advice and approval of the Building Seismic

Safety Council, a private sector organization formed in 1979 for the

purpose of enhancing public safety by providing a national forum to foster

improved seismic safety provisions for use by the building community.

The assessment of the Tentative Provisions was performed using the committee

structure shown in figure 1. Nine Technical Committees were formed with

interests that collectively cover the Tentative Provisions . The Joint

Committee on Review and Refinement consists of all voting members of the

Technical Committees. The chairmen of the Technical Committees form a Coordinating Committee.

Membership of each Technical Committee is made up of representatives of

organizations that have particular interest in the Tentative Provisions ; the participants are listed in the committee membership section of this

report

In addition to the voting members, each Technical Committee includes a non-voting member from each of the following organizations: The Applied

Technology Council (ATC), the Building Seismic Safety Council (BSSC)

and the National Bureau of Standards (NBS). The ATC representative served

as a technical resource to the committee since he was closely involved with

the development of the provisions of interest to the committee. The NBS

representative was the technical secretary throughout the effort. The

BSSC representative provided a link with the Building Seismic Safety

Council, which will be involved in trial designs and evaluations.

1.2 Committee Summary

Technical Committee 6 had the responsibility of reviewing and recommending

revisions to Chapter 10, Steel, of the Tentative Provisions for the Development of Seismic Regulations for Buildings (ATC 3-06). The committee is

comprised of six voting and three nonvoting members, drawn from industry,

professional organizations, standard development organization and governmental agencies. The first of three meetings which the committee had was held on December 11, 1978 at the National Bureau of Standards, Gaithersburg,

Maryland in conjunction with the organizing meeting. The second meeting

1
JOINT COMMITTEE ON

REVIEW AND REFINEMENT

COORDINATING

COMMITTEE

TECHNICAL COMMITTEES

Committee 1: Seismic Risk Maps

Committee 2: Structural Design

Committee 3: Foundat ions

Committee 4: Concrete

Committee 5: Masonry

Committee 6:

-- \ . Steel

f

. . i

' Jr Committee 7: Wood

Committee 8: Architectural,

Mechanical, and Electrical

Committee 9: Regulatory Use

Figure 1: Committee Structure
was held on February 13, 1980 in Washington, D.C. The third meeting was held in conjunction with the Joint Committee meeting which was held on July 16, 1980 at the National Bureau of Standrds. A brief summary of the

actions taken at each of these meetings is presented below.

At the first meeting, Mr. Jerome S. B. Iff land was elected as chairman

and Mr. William A. Sontag was appointed to serve as the committee's representative to Technical Committee 2, Structural Design. The committee

expressed the intention of concentrating its efforts on the review and

refinement of Chapter 10 and that it will also comment on those provisions

relevant to Chapter 10.

In order to obtain the widest possible participation from all interest

parties in the committee's effort, it was agreed that individual members

of the committee would contact professional and trade organizations.

Specifically, these organizations were asked to submit written comments

to the committee and, in addition, their representatives were invited

to attend scheduled meetings of the committee.

Although the schedule of the second meeting was announced in several

national professional publications and personal contacts which were made

by individual committee members, the meeting was attended only by the

members and their alternates. At this meeting, the committee addressed

all provisions of Chapter 10 with specific reference to written comments

which were submitted to the committee prior to the meeting and responses

to these comments which were prepared by Mr. Clarkson W. Pinkham, the

ATC representative.

In reviewing each of the provisions, the committee introduced the stateof-the-art information, carefully deliberated and incorporated into the

revision where appropriate. It was emphasized that the propoped revision

to the ATC 3-06 document will be used in trial designs for the economic

impact assessment.

Review of the provisions in Chapter 10 was completed during the first

day of the two-day scheduled meeting to the satisfaction of all who

attended the meeting. The committee agreed to vote on each of the

provisions separately. A ballot was distributed to six voting members

on April 22, 1980. Extensive review comments were distributed by

Mr. Charles DeMaria, representing the Building Seismic Safety Council

(BSSC) on the committee, to the committee members on March 24, 1980.

His comments were reflected in the voting. By July 1, 1980, the secretariat had received five ballots out of six voting members.

3
2.0 Committee Actions

'
2.1 Recommendations for Change

REVIEW AND REFINEMENT OF TENTATIVE SEISMIC PROVISIONS

PROPOSED CHANGE

TECHNICAL COMMITTEE: # 6, Steel COMMITEE ITEM NUMBER:

ATC-3-06 SECTION REFERENCE: 10.2.1

Delete 10.2.1 (B)

Change present 10.2.1 (C)and 10.2.1 (D) to 10.2.1 (B) and 10.2.1 (C),

respectively.

Add new 10.2.1 (D)

In AISC specifications 2.5, substitute Vu _< 0.68 in lieu of Vu 0.55.

FINAL BALLOT: 5 YES

0 NO

0 ABSTAIN

1 DID NOT VOTE

COMMENT ON PROPOSED CHANGE:

Deletion of 10.2.1 (B) is to prevent the use of Eq. (2.5-1) of part 2,

AISC Specs, which limits the maximum allowable shear to (0.55 Fy) td.

The committee recommends that the maximum allowable shear be increased

to (0.68 Fy) td.

Addition of sec. 10.2.1 (D) reflects this recommendation.

This is also to be consistant with the proposed AISC specifications.

5
REVIEW AND REFINEMENT OF TENTATIVE SEISMIC PROVISIONS

PROPOSED CHANGE

TECHNICAL COMMITTEE: # 6, Steel COMMITEE ITEM NUMBER

ATC-3-06 SECTION REFERENCE: 10.2

Change the seventh and eighth line to read as follows:

"...members or structural systems."

"Connections which do not develop the strength of the member or structural systems..."

FINAL BALLOT: 5 YES

0 NO

0 ABSTAIN

1 DID NOT VOTE

COMMENT ON PROPOSED CHANGE:

These changes reflect the cases where members need not develop

the full capacity of their cross section.

6
REVIEW AND REFINEMENT OF TENTATIVE SEISMIC PROVISIONS

PROPOSED CHANGE

TECHNICAL COMMITTEE: # 6, Steel COMMITEE ITEM NUMBER:

ATC-3-06 SECTION REFERENCE: 10.4

Delete sec. 10.4.1

Change sec. 10.4.1 to sec. 10.4.1 and to read as follows: "Ordinary moment

frames, space frames in building frame systems, and space frames incorporated

in bearing wall systems shall be designed and constructed in accordance with

Ref. 10.1, Part 1 or Ref. 10.2 or Ref. 10.3."

FINAL BALLOT: 5 YES

0 NO

0 ABSTAIN

1 DID NOT VOTE

COMMENT ON PROPOSED CHANGE:

Combine two separately stated requirements into one.

7
REVIEW AND REFINEMENT OF TENTATIVE SEISMIC PROVISIONS

PROPOSED CHANGE

TECHNICAL COMMITTEE: # 6, Steel COMMITEE ITEM NUMBER

ATC-3-06 SECTION REFERENCE: 10.5.1

Change the "exception" to read as follows:

1. Moment frames in one- and two-story buildings assigned to Seismic

Performance Category C may be Ordinary Moment Frames.

2. Moment frames in one-story building assigned to Seismic Performance

Category D may be Ordinary Moment Frames.

FINAL BALLOT: 5 YES

0 NO

0 ABSTAIN

1 DID NOT VOTE

COMMENT ON PROPOSED CHANGE:

One-story steel frame buildings have performed well during earthquakes.

Addition of "Exception 2" reflects these case histories, and the intent

of sec. 3.3.4 and 3.3.5.

8
REVIEW AND REFINEMENT OF TENTATIVE SEISMIC PROVISIONS

PROPOSED CHANGE

TECHNICAL COMMITTEE: # 6, Steel COMMITEE ITEM NUMBER:

ATC-3-06 SECTION REFERENCE: 10.6.5

Change the first line after the equation to read as follows:

"in place of Equation 1.15-2 of Ref. 10.1."

FINAL BALLOT: 5 YES

0 NO

0 ABSTAIN

1 DID NOT VOTE

COMMENT ON PROPOSED CHANGE:

The committee felt that the present equation is too complicated, and

a simplier form is desired. However, the committee agreed to retain

the equation in its present form, and examine its impact during the

trial design phase. Because the way in which the equation was derived,

the equation should replace only AISC Eq. 1.15-2 which is concerned

with bucking of the column web.

9
REVIEW AND REFINEMENT OF TENTATIVE SEISMIC PROVISIONS

PROPOSED CHANGE

TECHNICAL COMMITTEE: # 6, Steel COMMITEE ITEM NUMBER

ATC-3-06 SECTION REFERENCE 10.6.3

Change the third line to read "axiual force in the columns shall

not exceed 0.75Py."

FINAL BALLOT 3 YES

2 NO

0 ABSTAIN

1 DID NOT VOTE

COMMENT ON PROPOSED CHANGE:

Modifying the 0.6 factor to 0.75 was to reflect the change in the AISC

specifications (1979). Since the 1979 AISC specs, has already incorporated

the 0.75 factor, this item should be deleted (Pinkham's letter of April

24, 1980). It has been suggested that this factor be kept as 0.6 and

evaluate its impact by trial designs.

10
2.2 Recommendations for Trial Design

The committee recommends that the following items be evaluated

in trial designs:

1. The limitation of the axial force in column to 0.6 Fy and to

0.75 Fy (see Mr. Pinkham's letter of April 24, 1980).

2. The use of the equation in sec. 10.6.5 for a minimum web

thickness to be stiffened.

3. The effect of drift limitation on the economy of steel frame

structures (see Mr. De Maria's letter of March 24, 1980).
3.0 Committee Records

3.1 Minutes of Meeting

The minutes of each of the three committee meetings are included in this

report immediately following this page.
Minutes

Technical Committee 6: Steel

December 11, 1979

Room A434, National Bureau of Standards

1. 0 Call to Order

The Secretary of the task committee, H. S. Lew, serving as a temporary chairman called the meeting to order at 11:10 a.m. The secretary briefly reviewed the agenda of the meeting.

2.0 Introduction of Members

Individual members introduced themselves and identified their

affiliation. The following representatives were present:

Name Representative of

Frederick J. Palmer American Institute of Steel

Construction

William H. Smith American Iron and Steel Institute

Jerry Iff land American Society of Civil Engineers

John B. Scalzi Interagency Committee on Seismic

Safety in Construction

William A. Sontag Metal Building Manufacturers Assoc.

Norman K. Cohn Steel Plate Fabricators Assoc.

Clarkson Pinkham Applied Technology Council

H . S . Lew National Bureau of Standards

It was noted that TC 6 did not have a representation from the

Building Seismic Safety Council.

No visitors attended the meeting.

3.0

Selection of Chairman

Fred Palmer nominated Jerry Iff land for chairman and was seconded

by Norman Cohn.

13
By acclamation Jerry Iffland was elected as chairman.

The meeting was turned over to the new chairman.

4.0 Appointment of TC 6 Representative to TC 2

William Sontag was appointed and agreed to serve as TC 6

representative to TC 2.

5.0 Selection of Date for Working Meeting

Date: February 13, 1980 (9:00 a.m. - 5:00 p.m.}

February 14, 1980 (9:00 a.m. - 4:00 p.m.)

Location: Washington, D. C.

Jack Scalzi will assist in locating meeting place.

6.0 Invitation to the February Working Meeting

The secretary mentioned that the date and location of the

February meeting will be announced through the ASCE, NIBS and

NCSBCS newsletters.

The members agreed that it would be desirable to invite specific

groups in addition to the public announcement. Invitation will

be extended to participate in the working meeting;

ASCE Structural Division by Iffland

AISI Technical Committees by Smith

AISC Technical Committees by Palmer

AWS Technical Group by Smith

Res. Council on Structural Connections by Palmer

Steel Deck Institute by Smith

Steel Joist Institute by Palmer

Structural Stability Res. Council by Iffland

Council on Tall Buildings and Urban Habitat by Iffland

7.0 Report from TC 2

Bill Sontag reported that two individuals are nominated for

chairman and vice chairman. They are Howard Simpson, who represents ANSI and Hal Iyengar who represents ASCE. Depending upon

their availability, TC 2 will select their chairman.

8.0 Deliberation of Comments

The committee agreed that only those comments relevant to Chapter 10

will be discussed in TC 6. Those comments raised in TC 2 which are closely related to Chapter 10 will be discussed in TC 6.

14
9.0 Possible Topics of Refinements In Chapter 10

9. 1 Summary of Chapter 10 of ATC-3

Clarkson Pinkham summarized the salient features of

Chapter 10.

o Chapter 10 of ATC-3 deals with six specifications

AISC

AISI - cold-formed steel

AISI - cold-formed stainless steel

SJI - open web joists

SJI - long-span joists

AISI - steel cables for buildings

o Specific modifications to the current AISC specification

was summarized to reflect the strength design approach

in ATC-3.

9.2 Specific Comments Made by the Committee Members

o Exclusion of one-story buildings for use as essential

facility (category D) which do not meet compact shape

and bracing requirement. (Refer to Sect. 10.5.1)

o Full strength requirement for connections and ambiguity

related to load requirements

o Eccentric braced frame not being covered in ATC-3

o Drift requirement for one-story industrial buildings

o Dates for specifications cited as reference

o Design for overturning for high-rise buildings (raising

of forces vs. modification of dead load of structure)

10.0 Comments by the NBS Secretariat

o NBS secretariat will send out mailing labels to the TC 6

members for their use in mailing of comments to the TC 6

members

o The secretary requested that in order to save time, all

comments on chapter 10 should be sent to the NBS secretariat,

to the ATC representative and to the other members of TC 6.

o NBS secretariat will make a limited number of ATC-03 copies

available to those who wish to participate in the February

meeting.

15
11.0 Ad.j ournment

There being no further items before the committee, the meeting

adjourned at 3:45 p.m.

Respectfully submitted,

H. S. Lew, Secretary

16
Minutes

Technical Committee 6: Steel

February 13, 1980

Room 338, 1800 G Street, N.W.

Washington, D.C.

1.0

Call to Order

Chairman Iff land called the meeting to order at 9:00 a.m. This is the

first of a two-day open meeting scheduled for the committee to deliberate

on the issues submitted to the committee by individuals prior to the

meeting.

2.0

Attendance

Name Representative of

N. K. Cohn

D. S. Ellifrit

J. S. B. Iff land

A. L. Johnson

H. S. Lew

C. W. Pinkham

J. B. Scalzi

W. H. Smith

W. A. Sontag

Steel Plate Fabricators Association

Metal Building Manufacturers Association

American Society of Civil Engineers

American Iron and Steel Institute

National Bureau of Standards

Applied Technology Council

Interagency Committee on Seismic Safety

in Construction

American Iron and Steel Institute

Metal Building Manufacturers Association

Chairman Iff land noted that Mr. William Milek will replace Mr. Fred Palmer

for AISC representation. He also noted that Mr. Charles De Maria has been

designated as the representative of the Building Seismic Safety Council.

3.0

Review of ATC 3-06

The secretary reported that specific written comments that have been sent

to NBS have been distributed to the committee members and the written

responses to these comments by the ATC representative have also been sent

to the members by Mr. Pinkham.

It was agreed that the committee review all provisions in Chapter 10 on an item-by-item basis. In reviewing the provisions, the committee also

made reference to the comments made by Mr. De Maria dated March 11, 1977.

Sec. 10.1.: It was noted that the references 10.1 through 10.6 need

to be updated reflecting the lates versions of documents.

It was also recommended that the reference numbering system

be changed from Ref 10.1, etc. to Ref 10-1, etc.

Sec. 10.2.: For the cases of = 0.90 and i = 0.67, it was agreed that

"or structural system" be added to the existing statements

so that they be read as "Members and connections which

develop the strength of the members or structural systems"

and "connections which do not develop the strength of the

member, the structural system or do not conform to Sec.

10. 6. 1(A) 6."

17
10 . 2.1 Delete (B) - This is to prevent the use of Part II the current

AISC specs, for determining shear strength. It

is also to he consistent with the proposed AISC

specs

.

Change (C) to (B)

Change (D) to (C)

Add new (D) In AISC Sec. 2.5 Substitute "Vu <. 0.68"

in lieu of "Vu <. 0.55"

10.2.2 Add a comma to read "... AISI Sec. 2. 1.2. 2 of Ref. 10.2, and

AISI Sec. 3.9.1 ..."

10.2.3 No change

10.3 No change

10. A. 1 Delete

10.4.2 Change 10.4.2 to 10.4.1 and change the statement to read as follows

"Space frames in building frame systems and systems with

ordinary moment frames or where incorporated ... in accordance

with Ref. 10.1, Part 1 or Ref. 10.2 or Ref. 10.3."

10.5.1 Modify the exception to read as follows:

"EXCEPTION:

1. Moment frames in one-and two-story buildings assigned to

Seismic Performance Category C may be Ordinary Moment Frames.

2 . Moment frames in one-story buildings assigned to Seismic

Performance Category D may be Ordinary Moment Frames .

10.5.2 No change

Sec. 10.6 1.

2 . 3.

4.

5.

6 .

7.

4.0 Adj ournment

There being no further items before the committee, the meeting was adjourned at 3:30 p.m.

Respectfully submitted,

H. S. Lew, Secretary

No change

Change ASTM designations to reflect the latest versions.

Change the statement to read "... exceed 0.75 P " instead

of "... exceed 0.60 P ." ^ No change ^ Change the sentence after the equation to read "in place

of Equation 1.15-2 of Ref. 10.1."

Change the statement to read" "Beam to column connected

in special moment frames shall develop..."

Change the statement to read: "Change the start of the

second paragraph eH-Page-5-62-in of AISC Sec. 2.9..."

18
Minutes

Technical Committee 6: Steel

July 16, 1980

National Bureau of Standards

Washington, DC

1.0 The meeting was called to order by acting chairman William Sontag

at 5:30 p.m.

2.0 Those in attendance were: N. K. Cohn

C. W. Pinkham

W. A. Sontag

W. Milek

A. L. Johnson

C. DeMaria

H. S. Lew

W. H. Smith

Jack Scalzi

2 visitors.

3.0 Bill Smith made a request to the committee for a time slot for his

presentation on the eccentric braced frame system before the joint

committee. Smith introduced, in his letter of January 11, 1980, and

at the February 13, 1980 meeting, the eccentric braced frame systems

for committee consideration as an item for possible inclusion in the

revision process of ATC 3-06. At the February meeting it was decided

that this issue be tabled due to the lack of criteria available for

the application of the eccentric braced frame system. At the present

meeting. Bill Smith distributed a subcommittee report on this system

prepared by the Structural Engineers Association of Northern

California's Subcommittee on Eccentric Braced Frame and recommendations to incorporate it in the ATC 3 document prepared by the American

Iron and Steel Institutes' Committee on Construction Codes and

Standards.

In the discussion that followed, it was pointed out that at the

present time it would not be possible to consider the inclusion

of the eccentric brace frame system in trial designs due primarily

to the fact that no bench mark criteria are available to which the

new system can be compared.

A motion was made by William Milek and seconded by Jack Scalzi

that Committee 6, Steel, recommend that the relative merits of

the eccentric braced frame system be evaluated and considered for

inclusion in "the final resource document by BSSC." The motion was carried unanimously.

The committee further recommended that the committee representatives

to Committee 10A (Sontag and Smith) express its view that the

eccentric braced frame system as a special item be considered as

a candidate for trial design.

19
2

The committee agreed that a ten minute slot be allocated for

Bill Smith to make his presentation on the eccentric braced

frame system.

The meeting was adjourned at 6:30 p.m.

Respectfully submitted,

H. S. Lew, Secretary

20
3.2 Committee Roster

COMMITTEE 6: Steel

American Institute of Steel Construction

William A. Milek

American Institute of Steel Construction, Inc.

Wrigley Building

400 North Michigan Ave.

Chicago, ILL 60611

Phone: 312-670-2400

American Iron and Steel Institute

Dr. Albert L. Johnson Alter:

Staff Representative

American Iron and Steel Institute

1000 16th Street, N.W.

Washington, D.C. 20036

Phone: 202-452-7184

Mr. William H. Smith

Regional Director

American Iron and Steel

Institute

Latham Square Building

508 Sixteenth Street

Suite 704

Oakland, CA 94612

Phone: 415-763-6751

American Society of Civil Engineers

Mr. Jerry Iffland (Chairman)

Iffland, Kavanagh, Waterbury

1501 Broadway

New York, New York 10036

Phone: 212-933-2000

Interagency Committee on Seismic Safety in Construction

Mr. John B. Scalzi

National Science Foundation

Room 1130

1800 G Street N.W.

Washington, D.C. 20550

Phone: 202-632-0648

21
Committee 6 (continued)

Metal Building Manufacturers Association

Mr. William A. Sontag

Pascoe Steel Corporation

P. 0. Box 2628

Pomona, CA 91766

Phone: 714-623-1411

(representative to Committee 2)

Alter: Duane Ellifrit

Director of Research & Engineering

Metal Building Manufacturers

Assoc.

1230 Keith Building

Cleveland, OH 44115

Steel Plate Fabricators Association

Mr. Norman K. Cohn

Chief Engineer

Mississippi Valley Structural Steel Co.

Sub. of Bristol Steel & Iron Works

3117 Big Bend Blvd.

St. Louis, MO 63143

Phone: 314-644-2200

Applied Technology Council

Mr. Clarkson Pinkham

President, S B Barnes Assoc.

2236 Beverly Blvd.

Los Angeles, CA 90057

Phone: 213-382-2385

Building Seismic Safety Council

Mr. Charles De Maria

Building Seismic Safety Council

H. J. Brunnier Associates

Structural Engineers

55 New Montgomery Stret

Suite 608

San Francisco, CA 94105

Phone: 415-781-0370

22
Committee 6 (continued)

National Bureau of Standards

Dr. H. S. Lew

Secretariat

Committee 6, Steel

National Bureau of Standards

Rm. B-168, Bldg. 226

Washington, D.C. 20234

Phone: 301-921-2647

23
.

3.3 Selected Committee Correspondence and Applied Technology Council Comments

. SMNN
San Jose State University

WASHINGTON SQUARE

SAN JOSE. CALIFORNIA 951S2

SCHOOL OF ENGINEERING

Department of Civil Engineering and Applied Mechanics (408) 277-2488

March 17, 1980

Mr. Gerald Ifland

Chairman, Committee 6 - Steel

Ifland, Kavanaugh, Waterbury, P.C.

1501 Broadway

New York, NY 10036

Dear Mr. If land:

Mr. William Smith of AISC has asked me to send you these more

detailed versions of my comments on Chapter 10 of the ATC 3-06 Document.

Comment 1

Section 10.1, Reference Documents: The latest versions of documents

should be given in this list. The 1978 Edition of the AISC Specifications has been published since the formation of the original list in

this section.

Comment 2

Design Provisions for Braced Steel Frames: Braced Frame provisions in

the Recommended Lateral Force Provisions of SEAOC required that "all

members in braced frames shall be designed for 1.25 times the force due

to the specified base shear.

I cannot locate an equivalent provision for this extra factor of 1.25

in. the ATC 3-06 provisions; neither in the 0 factor nor in the R factor.

Control on the net area of- bolted bracing connections: The commentary

to Section 1. 5.1.1 of the 1978 AISC Specifications (page 105) states that

the net to gross area ratio:

So as to provide general yielding rather than fracture of net area.

It is most necessary that this area ratio, or a more conservative equivalent, be required for connections in seismic resistant braced frames.

Comment 3

THE CALIFORNIA STATE UNIVERSITY AND COLLEGES

25
March 17, 1980

Mr. Gerald Ifland

Page 2

In general, all provisions should be reviewed (for example, the

tensile capacities of threaded areas of bolts) so as to assure that a substantial amount of yielding deformation can occur before fracture

or sudden failure of an element or connection. The safety factor

against fracture should be 3 to 5 rather than the value of 2 given in

the AISC Section 1.5. 1.1 Commentary.

Sincerely yours.

Professor of Civil Engineering

Chairman, Seismology Committee

Structural Engineers Association of California

TZ:cm

cc: Dr. H. S. Lu, Secretary

Committee 6 - Steel

26
S. B. BARNES AND ASSOCIATES

CONSULTING STRUCTURAL ENGINEERS

S a BARNES johk hoeft

ALB I N W JOHNSON

2236 BEVERLY BOULEVARD

LOS ANGELES CALIFORNIA 90037

362.2365

CLARKSON W PINKHAM ROBERT W BPRACKLEN

April 24, 1980

Mr. Jerone S. B. Iff land

Iff land Kavanagh Waterbury, P.C.

Architects -Eng ineers

1501 Broadway

New York, New York 10036

Dear Jerry:

I am not a voting member of the Committee but I do have one "bone" to pick with one item on the ballot from H. S. Lew.

The item in Sec. 10.6.3 was an item discussed in the letter

from Charles DeMaria but I do not recall the item being

discussed in Washington. If it was decided to modify the

0.6 factor to 0.75 the item should be deleted because that

is already given in that manner in AISC-79 (Sec. 2.3.2.)

As for the merits of the change, I concur with C. De Maria

that the 0.75 factor would be appropriate for those columns

which are not depended on to provide the primary stability

of the building. For the reasons given on page 442 of

ATC-3-06, I do feel that 0.6 factor is important to keep

for those columns providing the primary lateral stability

to the structure. For this reason I could recommend a modification to the current ATC provision but not a deletion.

Even if it were chosen as a final matter to delete this provision, I feel it should remain as is so that the design

office check could see how serious the problem described by

C. DeMaria actually is

cc : W . A . Milek

A. L. Johnson

W. H. Smith

J. B. Scalzi

W. A. Sontag

D. Ellifr it

N . K . C ohn

H. ' S

Lew

C. DeMaria

Very truly yours

CWP.ls C. W. Pinkham

27
H. J. BRUNNIER ASSOCIATES

STRUCTURAL ENGINEERS

55 NEW MONTGOMERY STREET - SUITE 608 • SAN FRANCISCO. CALIFOR NIA 94 1 05 - 415 781.0370

M. J. BRUNNIER 1*82 - 1S7I

H. C. POWERS

H. l_ LYELJ.

C. D. DE MARIA

S. E. TEIXEIRA

A. P. STEVENS

TO: Members of NSB ATC-3 Technical Committee 6

March 24 , 1980

J. S. Iffland. Chairman

F.J Palmer

A. L. Johnson

W. H. Smith, Alternate

J. B. Scalzi

W. A. Sontag

D. Ellifrit, Alternate

N . K . Cohn

E. Pinkham

H. S. Lew, Secretary

Gentlemen:

Enclosed are comments on the steel chapter and related sections

of ATC-3-06. The lateness of submission is a result of my late

appointment to the committee.

Sincerely yours.

Charles De Maria

Building Seismic Safety Council

enclosures

CDD/ng

f

28
STRUCTURAL ENGINEERS

REVIEW OF THE STEEL SECTIONS OF ATC 3-06

TENTATIVE PROVISIONS FOR THE DEVELOPMENT OF

SEISMIC REGULATIONS FOR BUILDINGS

March 19, 1980

GENERAL COMMENTS

The purpose of the present review of ATC 3-06 is to discover and

eliminate any obvious errors and inconsistencies in the document

prior to a program of testing the provisions with trial designs of

a broad spectrum of building types and configurations. The trial

designs may bring to light the need for further modification of the

provisions in order to produce structures comparable with those which

have been observed to perform satisfactorily in past earthquakes or

in order to allow for a more economical use of construction materials.

Following the trial designs, it is absolutely essential that a review

and evaluation of the results and any necessary changes in the provisions

be made prior to their adoption as a model code. In the event of

adoption of the provisions as a code it is also essential that an organization and procedure be established to correct and update the

code as further experience with its application and advances in

seismic resistant design necessitate.

Of prime concern to the steel industry is the effect that drift

limitation criteria will have on the economy of steel frame structures.

This effect should be carefully evaluated in the trial designs. We

recommend that story drift limitations be carefully re-evaluated and

that no stricter limitations be set than those required to provide a reasonable degree of protection for finish materials. We further

recommend that consideration be given to the elimination of drift

limitation requirements foT structures without brittle finish materials.

ATC 3-06 does not mention a type of structural steel system, the

eccentric braced frame, which is undergoing rapid development and

acceptance as an economical seismic resistant system. We recommend

that trial designs include this system and that it be incorporated

into the final document, together with the proper criteria for its use.

29
Review o ! Seismic Regulations

page two

The seismic response modification coefficient, R, for special reinforced

concrete moment frames appears high when compared with the similar

value for special structural steel frames. Work at the University of

California involving cyclic loading at high strain levels suggest a greater differentiation between the two materials. Special concrete

frames are highly rated even though we have little data on the behavior

of such construction during severe earthquakes and know that the

practical problems of designing, detailing and placing the required

reinforcement are so great that the designs must be compromised during

the construction period. We recommend a greater differentiation between

the R values for special steel and reinforced concrete moment frames in

recognition of the superior materials, workmanship and past performance

of structural steel frames.

In general, the provisions of ATC 3-06 which affect the. use of steel

are consistent with the philosophy of the document. This philosophy

involves the application of realistic seismic forces and utilization

of member capacities to resist those forces. Severe drift limitation

criteria however, may prevent the full utilization of member capacities.

Specific comments on the detailed provisions follow.

COMMENTS ON THE DETAILED PROVISIONS OF ATC 3-06

1.6.2 (F) This paragraph is unduly restrictive. Continuous Special

Inspections should be limited to welds determined to be critical by

the person responsible for the structural design. Credit should be

given to "Approved Fabricators" participating in the AISC Quality

Certification Program. The standards for special inspections such as

the AWS Dl.l Structural Welding Code and the Research Council Specification for Structural Joints using ASTM A325 or A490 Bolts should be cited.

1.6.3 (D)

2

Ultrasonic testing of partial penetration groove welds is

meaningless and should be deleted. Visual inspection of the root pass

is the most reliable method of insuring quality.

r 10 .

1

The reference documents should be updated to the most recent

editions. Additional references to AWS D.1.1 Structural Welding Code,

AWS D.1.3 Specification for Welding Sheet Steel, and the Research

Council Specification for Structural Joints using ASTM A325 o^ A490

Bolts should be included.

10.2 It is not clear how the strength of members which have flange

end connections utilizing high strength bolts should be computed.

Is reduction of flange area up to 15% ignored as per Reference 10.1

Section 1.10.1, or is the entire assembly penalized by requiring a capacity reduction factor of 0.67?

30
Rcvic-w of Seismic Regulations

page three

10.2 (cont'd) The capacity reduction factors should be re-evaluated,

considering the reliability of steel and the fact that the factors are

based on the specified minimum yield point which is generally exceeded.

The reference to Section 10.6.1(A)6 should be corrected to read

"Section 10.6, Item 6".

10.5.1 The limitation of Ordinary Moment Frames to one and two story

buildings in Performance Category C and their prohibition in Performance Category D is contrary to the Provisions of Sections 3.3.4 and

3.3.5 which permit their use up to a height of 160 feet for Category

C and up to a height of 100 feet for Category D. It is our opinion

that Sections 3.3.4 and 3.3.5 represent the intention of ATC-06 with

the higher loadings resulting from the lower R value for Ordinary

Moment Frames reducing the need for post elastic performance. In any

event, Ordinary Moment Frames should be permitted for one-story performance Category D structures.

10.6,

Item 1 The modifications to Part 2 of ref. 10.2 make difficult

reading, however, it appears that the compact section and lateral

bracing of compression flange requirements of Part 2 are applicable to

Special Moment Frames. We are in agreement with these requirements.

10.6,

Item 3 Limiting the axial force in columns to 0.60 times yield

creates almost insoluble problems in the design of corner columns of

tall buildings with high overturning moments and the requirement for

orthoganal combinations. High' strength steels are not permitted, and

simply increasing the size of comer columns will not work as differential shortening of corner columns will introduce huge gravity moments

and dishing of floors under vertical loading. We recommend "The axial

force in the columns shall not exceed 0.75 Py".

10.6,

Item 4 The term "plastic capacity of the joint" needs further

definition. Is it the sum of the beam capacities proportioned to the

column above and the column below, or is it the more unlikely combination

of the sum of the beam capacities plus the column above applied to the

column below? It is not clear for conditions A and B if vertical load

is considered in either the plastic moment capacity of the joint or the

strength of the column splice.

10.6,

Item 5 The intent of requiring the panel zone to resist shears

due to deforming the frame 2 times that resulting from the prescribed

forces is not clear. If the intent is to prevent the initial hinge

from being due to shear yielding in the panel zone, this is not necessarily beneficial. High ductility factors of steel frames are merited

in part due to shear yielding in the panel zone without loss of stability.

31
Review of Seismic Populations

page four

10.6, Item 5 (cont'd) The Chen-Newlin formula for critical crippling

stress on a column web was developed from load tests on a small number

of rolled wide flange sections in the 8" to 12" range. The authors

concluded that significant yielding of the web opposite the load was

a "local problem" not affecting the buckling strength of the web and

dismissed this factor from further consideration. ATC 3-06 should

not dismiss this factor, for the significant yielding of the column

web will permit the beam to rotate without developing its plastic

moment. If we accept the Chen-Newlin formula for critical crippling

stress on a column web, and accept the parabolic combination with

shear stresses as proposed in the commentary, and neglect entirely

the axial load stress in the column, then the formula might be substituted for the Equation 1.15-2 of ref. 10.1, but should not be

substituted for Equation 1.15-1. Use of the above formula alone

will permit thinner webs without load stiffeners than Equation 1.15-1

which is already unconservative in that its use allows some inelastic

deformation at the working stress level. In view of the complexity

and uncertainies involved in the formula presented, we recommend that

a simpler formula or procedure be devised to control joint panel zone

thickness.

10.6, Item 6 The same questions concerning the method of computing

member strength raised by Section 10.2 apply to this item.

C. 3. 3.

3

This section should be amplified to permit the use of moment

frames to resist forces in the direction of one axis of the structure

and braced frames to resist forces in the direction of the other axis

of the structure. V?e believe that this is the intent of ATC 3-06,

however, the issue is clouded by use of the term "three-dimensional

space frame" in Section C.3.3.1.

32
NBS-114A (rev. 2-80

U.S. DEPT. OF COMM. 1. PUBLICATION OR 2. Performing Organ. Report No. 3. Publication Date BIBLIOGRAPHIC DATA

REPORT NO.

SHEET (See instructions) NBSIR 80-2111-6 October 1980

4. TITLE AND SUBTITLE

Review and Refinement of ATC 3-06 Tentative Seismic Provisions - Report of

Technical Committee 6: Steel

5. AUTHOR(S)

H. S. Lew

G. PERFORMING ORGANIZATION (If joint or other than NBS. see instructions) 7. Contract/Grant No.

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE 8. Type of Report & Period Covered

WASHINGTON, D.C. 20234

Final

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City. State. ZIP)

Federal Emergency Management Agency

Washington, D.C. 20472

10.

SUPPLEMENTARY NOTES

| | Document describes a computer program; SF-185, FIPS Software Summary, is attached.

11.

ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here)

The Tentative Provisions for the Development of Seismic Regulations for

Buildings were developed by the Applied Technology Council to present,

in one comprehensive document, current state-of-knowledge pertaining to

seismic engineering of buildings. The Tentative Provisions are in the

process of being assessed by the building community. This report is one

of a series of reports that documents the deliberations of a group of

professionals jointly selected by the Building Seismic Safety Council

and the National Bureau of Standards and charged with reviewing the

Tentative Provisions prior to the conduct of trial designs. The report

contains the recommendations and records of the committee charged with

review of the steel design provisions. The committee made 6 recommendations for revisions to the Tentative Provisions and three additional

recommendations. These recommendations were made to the parent group,

the Joint Committee on Review and Refinement, and their action on these

recommendations is documented in a companion report.

12.

KEY WORDS (Six to twelve entries; alphabetical order; capitalize on ly proper names; and separate key words by semicolon s) Building; building codes; building design; earthquakes; engineering; standards;

steel; structural engineering

13. AVAILABILITY 14. NO. OF

CT1 Unlimited

| | For Official Distribution. Do Not Release to NTIS

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