NBSIR 80-2111-7 mill

A1110S 087053

Review and Refinement of

ATC 3-06 Tentative Seismic Provisions

Joint Committee on Review and Refinement

1

Coordinating Committee

Technical Committee

Committee 1: Seismic Risk Maps

Committee 2: Structural Design

Committee 3: Foundations

Committee 4: Concrete

Committee 5: Masonry

Committee 6: Steel

Committee 8: Architectural, Mechanical and

Electrical

Committee 9: Regulatory Use

Report of Technical Committee 7:

; Wood

This report documents the deliberations of a group of professionals jointly

selected by the Building Seismic Safety Council and the National Bureau

of Standards and is for use in modifying the Tentative Provisions for trial designs

U.S. Department of Commerce

National Bureau of Standards

National Engineering Laboratory

Center for Building Technology

Washington, D.C. 20234 October 1980

NBSIR 80-2111-7

REVIEW AND REFINEMENT OF ATC 3-06

TENTATIVE SEISMIC PROVISIONS

Report of Technical Committee 7: Wood

Daniel H. Brown, Chairman, American Plywood Association

Charles W. C. Yancey, Secretary, National Bureau of Standards

Thomas E. Brassell, American Institute of Timber Construction

Thomas G. Williamson, American Society of Civil Engineering

Marco F. Venturino, Interagency Committee on Seismic Safety in Construction

Roderick B. Buchan, National Forest Products Association

Lawrence A. Soltis, United States Forest Products Laboratory

Edwin G. Zacher, Applied Technology Council

Roy G. Johnston, 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

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 engineerng 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 provisions for the design and detailing of wood structures.

The committee made 14 recommendations for revisions to the Tentative

Provisions . 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.

Keywords: Building; building codes; building design; earthquakes; engineering

standards; structural engineering; wood.

iii
TABLE OF CONTENTS

Page

1.0 INTRODUCTION 1

1.1 General 1

1.2 Committee Summary 1

2.0 COMMITTEE ACTIONS 5

2.1 Recommended Changes 5

3.0 COMMITTEE RECORDS 22

3.1 Minutes of Meetings 22

3.2 Roster 25

3.3 Selected Committee Correspondence and Applied

Technology Council Comments 27

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 7 held its organizational meeting on Tuesday December 11,

1979 at the National Bureau of Standards. Three of the six designated

voting members were in attendence. It should be noted that the American

Socity of Civil Engineers - of the six designees - had not named a representative at the time of the meeting. Therefore, only five voting members

were expected to be in attendence.

1
JOINT COMMITTEE ON

REVIEW AND REFINEMENT

COORDINATING

COMMITTEE

TECHNICAL COMMITTEES

Committee Is Seismic Risk Maps

Committee 2: Structural Design

Committee 3: Foundat ions

Committee 4: Concrete

Committee 5: Masonry

Committee 6: Steel

Committee 7: Wood

Committee 8: Architectural

,

Mechanical, and Electrical

Committee 9: Regulatory Use

Figure 1: Committee Structure
Mr. Daniel Brown (American Plywood Association) and Mr. Robert Hewett (National

Forest Products Association) were elected Chairman and Vice Chairman respectively.

Also, Mr. Edwin Zacher (ATC) was selected as the committee's representative to

Committee 2 on Structural Design.

The remainder of the day-long meeting was devoted to discussions of some ATC 3-06 provisions of concern to the Committee such as: a) orthogonal con- nection provisions, b) R and 0 factors, and c) computation of the natural

period of buildings with relatively flexible diaphragms according to the

provisions. Messrs. Brown and Hewett raised a number of prepared questions

and comments, and it was expected that some of their concerns would be translated into written proposals for revisions to the ATC 3-06 provisons in

Chapter 9.

The one-day Public Meeting scheduled for February 22 in San Diego was can- celled in mid-February for several reasons: 1) the committee had received

no response from the public, expressing an interest in attending the meeting;

2) several of the committee members were prohibited by travel limitations

from attending; 3) only one set of written comments had been received by

the Secretariat; and 4) it was the concensus of the committee that most

of the recommendations received from Mr. Daniel Brown could be discussed

by phone. No futher meetings were scheduled by the committee.

On 9 January, 1980, a set of written recommendations were received from

Mr. Daniel Brown (APA) . The transmittal letter was dated 4 January 1980.

Concurrently, Mr. Brown sent a copy of his recommendations to the other

committee members. Mr. Edwin Zacher (ATC) responded to Mr. Brown's recommendations in a letter dated 1 February 1980. In addition, Mr. Zacher

addressed several anticipated comments from other committee members. The

Secretariat received no other written recommendations or comments pertaining

to Mr. Brown's recommendations. One more sequence of comments by Mr. Brown

and response by Mr. Zacher occurred before the evolution of a final set of

recommendations for committee ballot.

On 10 March 1980, the Secretariat to Committee 7 received a memorandum from

the Secratariat of Committee 9 (Regulatory Use) which contained two review

comments from members of Committee 9. One comment was from Mr. David E.

Johnson (National Association of Home Builders) who suggested that the

guidelines for top plates (para. 9.7.1(B)) be expanded to cover the specific

case of studs being located directly beneath the joists. The other comment was from Mr. G. Robert Fuller (Interagency Committee on Seismic Safety in

Construction) who suggested that the anchor bolt requirements contained

in Section 9.7 be made more stringent. These comments were transmitted

to the members of Committee 7 on 24 March 1980 and the members' responses

on 31 March. Receiving no other responses to these recommendations, the

Secretariat sent a copy of Mr. Zacher 's response to each committee member

on 6 May 1980 and followed up on the written correspondence with a phone

canvass on the dates of May 15 and 16. It was determined from the canvass

that the committee members were in agreement with Mr. Zacher 's position

of not making either of the suggested revisions. This result was conveyed

to the Secretariat of Committee 9 in a memorandum dated 29 May 1980, thereby

terminating action on the subject recommendations.

3
A final set of suggested revisions to Chapter 9 and to a couple of other

Chapters was prepared by the Secretariat and transmitted to the members

of Committee 7 as a letter ballot on 27 May 1980. The recommended revisions

stemmed solely from the suggestions of Mr. Daniel Brown and the corresponding

responses of Mr. Edwin Zacher. The results of the balloting are indicated

beside each ballot item in the set of recommendations included herein.

<r

4
2.0 Committee Actions

2.1 Recommended Changes

"

• /

O tvt ' 1 1 is. ; • ’ ' y .

; •:!
REVIEW AND REFINEMENT OF TENTATIVE SEISMIC PROVISIONS

PROPOSED CHANGE

TECHNICAL COMMITTEE: #7, Wood COMMITTEE ITEM NUMBER:

ATC-3-06 SECTION REFERENCE: 9.1

Add new references:

9.15 Plywood Design Specifications, APA, 1978

9.16 Plywood Diaphragm Construction, APA, 1978

FINAL BALLOT : 5 YES

NO

ABSTAIN

DID NOT VOTE

COMMENT ON PROPOSED CHANGE:

Plywood working stresses are included in the Plywood Design Specification

It will be necessary in some cases to check the shear strength of plywood

in order to design a plywood diaphragm by the principles of mechanics.

This information is not contained in any of the other references in

Chapter 9.

6
REVIEW AND REFINEMENT OF TENTATIVE SEISMIC PROVISIONS

PROPOSED CHANGE

TECHNICAL COMMITTEE: #7, Wood COMMITTEE ITEM NUMBER: 2

ATC-3-06 SECTION REFERENCE: 9.1

Change Reference 9.12 to read:

One- and Two-Family Dwelling Code , 1975*

*One of the affirmative voters made an editorial note that the latest edition

of this code is 1979 . FINAL BALLOT: YES

NO

ABSTAIN

DID NOT VOTE

COMMENT ON PROPOSED CHANGE:

As written in 9.12, it appears as though each of the three model codes has

a one- and two-family code. The One- and Two-Family Dwelling Code is a single document written by the four model code organizations, the three

listed in 9.12 plus the American Insurance Association.

7
REVIEW AND REFINEMENT OF TENTATIVE SEISMIC PROVISIONS

PROPOSED CHANGE

TECHNICAL COMMITTEE: #7, Wood COMMITTEE ITEM NUMBER:

ATC-3-06 SECTION REFERENCE: 9 - 2

Change the capacity reduction factor, for shear on diaphragms and shear

walls, from 0.75 to 0.85.

FINAL BALLOT : 5 YES

NO

ABSTAIN

DID NOT VOTE

COMMENT ON PROPOSED CHANGE:

The change was suggested on the basis of the results of a diaphragm test

program conducted by the American Plywood Association. It was found that

the average load factor against failure was 3.65, which exceeds the product

of the multiplying factor, 2, (see Section 9.2) times 0.85 by more than 2.

In light of this comparison, the Committee agreed to increase the value of

<t> from 0 ; 75 to 0.85.

8
REVIEW AND REFINEMENT OF TENTATIVE SEISMIC PROVISION?

PROPOSED CHANGE

TECHNICAL COMMITTEE: #7, Wood COMMITTEE ITEM NUMBER: 3(B)

ATC-3-06 SECTION REFERENCE: 9.2

Revise the tabulation of strength reduction factors as follows:

All stresses in wood members </> = 1.0

Bolts and other timber connectors

not listed below <t> = 1.0

Shear on carriage bolts not

having washers under the head <b = 0.67

Lag screws and wood screws <t> - 0.90

Shear on diaphragms and shear

walls as given in this chapter <t> = 0.85

FINAL BALLOT: YES

NO

ABSTAIN

DID NOT VOTE

COMMENT ON PROPOSED CHANGE:

The change deletes the </> values for nails in shear in plywood diaphragms of

Group III species members ($ = 0.82) and Group IV species members (</> = 0.65)

because these values are included in Tables 9-1 and 9-2 of ATC-3-06. The </> value for shear on diaphragms and shear walls was changed from 0.75 to 0.85

per Committee Item No. 3(A). The two previous values of <t> (0.90 & 3.6/N)

for lag screws and wood screws were changed to a single value of = 0.90.

9
REVIEW AND REFINEMENT OF TENTATIVE SEISMIC PROVISIONS

PROPOSED CHANGE

TECHNICAL COMMITTEE: #7, Wood COMMITTEE ITEM NUMBER: 4

ATC-3-06 SECTION REFERENCE: 9.4.1(c)

Delete this subsection.

FINAL BALLOT: _5 YES

NO

ABSTAIN

DID NOT VOTE

COMMENT ON PROPOSED CHANGE:

This change was approved in view of the fact that the 1977 edition of the

National Design Specification (Reference 9.1) has covered this requirement.

10
REVIEW AND REFINEMENT OF TENTATIVE SEISMIC PROVISIONS

PROPOSED CHANGE

TECHNICAL COMMITTEE: #7, Wood COMMITTEE ITEM NUMBER: 5

ATC-3-06 SECTION REFERENCE: 9.5.3(A)

Replace the existing language with the following: Reference 9.1 shall be

modified as follows: In 8. 8. 1.4, replace the existing language with

"When more than one nail or spike is used in a joint of a frame or similar

component, the total design value shall be determined in the same manner

as is done in 8.3. 2. 3." In 8.8.6, change two-thirds to one-half .

FINAL BALLOT: 4 YES (1 with comment)

1 NO

ABSTAIN

DID NOT VOTE

COMMENT ON PROPOSED CHANGE:

The opinions of the negative voter were that: 1) Section 8. 3.2.

3

of the

National Design Specification (NDS) does not apply to nails; thus the

proposed change is inappropriate and is not substantiated, and 2) there

is no justification for the suggested change in NDS 8.8.6 since the twothirds factor has been in the NDS since its inception. The affirmative

voter that had comments was of the opinion that Committee 7 should be

hesitant to reference the NDS and then to suggest changes in the NDS.

He also felt that the modifications suggested for the NDS were based on "gut" feelings rather than fact.

11
REVIEW AND REFINEMENT OF TENTATIVE SEISMIC PROVISIONS

PROPOSED CHANGE

TECHNICAL COMMITTEE: #7, Wood COMMITTEE ITEM NUMBER: 6

ATC-3-06 SECTION REFERENCE: 9.5.3(B)

Remove this subsection and transfer it to Section 9.6.3.

FINAL BALLOT: _5 YES

NO

ABSTAIN

DID NOT VOTE

COMMENT ON PROPOSED CHANGE:

The Committee agreed with the imposition of special requirements in Category D

construction in so far as plywood over gypsum sheathing is concerned. It was

felt that prohibiting the use of gypsum sheathing as a part of the seismic

resisting system was not justified for Category C construction. This opinion

was based on the results of some shear tests on walls using plywood applied

over gypsum wallboard. The average load factor obtained in the testing

program was greater than 4.5.

12
REVIEW AND REFINEMENT OF TENTATIVE SEISMIC PROVISIONS

PROPOSED CHANGE

TECHNICAL COMMITTEE: #7 , Wood COMMITTEE ITEM NUMBER

ATC-3-06 SECTION REFERENCE: 9.6.3

The existing sentence in subsection 9.5.3(B), without the heading, should

become the first sentence in Section 9.6.3.

FINAL BALLOT : _5 YES

NO

ABSTAIN

DID NOT VOTE

COMMENT ON PROPOSED CHANGE:

13
REVIEW AND REFINEMENT OF TENTATIVE SEISMIC PROVISIONS

PROPOSED CHANGE

TECHNICAL COMMITTEE: #7. Wood COMMITTEE ITEM NUMBER: 8

ATC-3-06 SECTION REFERENCE: 9.7.1(A)

Section 9.7.1 can be modified as follows: ...provided at not over 6 feet on center for buildings two stories, 20 feet, or less in height and at not over 4 feet on center for buildings over this height but three stories, or

35 feet or less in height . Anchor bolts shall have a minimum embedment of

8 diameters.

FINAL BALLOT : _3 YES

_2 NO

ABSTAIN

DID NOT VOTE

COMMENT ON PROPOSED CHANGE:

The proposed change was predicated on the fact that the Uniform Building

Code has permitted anchor bolt spacing of 6 feet for many years with no documented detrimental consequences in recent earthquakes including the

1971 San Fernando, California Earthquake. One minority view was that in

the Great Alaska Earthquake there were some sill/foundation anchorage

failures caused by undefined forces. Until we know what kind of forces

are acting, the anchorage requirements should be more, rather than less,

conservative. A second view was that bolts should not be less than 5/8 in

diameter at 4'0" on center with at least 7 in embedment. The need for

strengthening the anchorage provision was also suggested by a member of

Technical Committee #9.

14
REVIEW AND REFINEMENT OF TENTATIVE SEISMIC PROVISION?

PROPOSED CHANGE

TECHNICAL COMMITTEE: #7, Wood COMMITTEE ITEM NUMBER

ATC-3-06 SECTION REFERENCE: 9, 7. 1(c)

Delete the word "stud" at the end of the sentence and add the following

" . .

studs unless specifically excepted In Section 9.7.3 .

FINAL BALLOT: * YES

NO

"ABSTAIN

"DID NOT VOTE

COMMENT ON PROPOSED CHANGE:

15
REVIEW AND REFINEMENT OF TENTATIVE SEISMIC PROVISIONS

PROPOSED CHANGE

TECHNICAL COMMITTEE: #7, Wood COMMITTEE ITEM NUMBER : 10

ATC-3-06 SECTION REFERENCE: 9 - 7 - 3 ( B )

Add the sentence: "Blocking need not be provided at horizontal joints."

FINAL BALLOT: YES

NO

1 ABSTAIN

DID NOT VOTE

COMMENT ON PROPOSED CHANGE:

It was the view of the proponent of this change that for conventional lighttimber construction it is not necessary to block horizontal joints in plywood

sheathing. The primary basis for this opinion was the results of four tests on walls which were sheathed with 5/16" cedar panels. The minimum ultimate

load obtained for these Group IV species (i.e. the lowest strength group

recognized for sheathing applications) was 4400 lb. It is implied that this

magnitude is sufficiently high to preclude the failure of the plywood bracing

panels

.

16
REVIEW AND REFINEMENT OF TENTATIVE SEISMIC PROVISIONS

PROPOSED CHANGE

TECHNICAL COMMITTEE: #7, Wood COMMITTEE ITEM NUMBER: 11

ATC- 3-06 SECTION REFERENCE: Table 9-1

o Change the table heading to read: ALLOWABLE SHEAR IN POUNDS PER FOOT FOR

HORIZONTAL PLYWOOD DIAPHRAGMS WITH FRAMING OF DOUGLAS FIR-LARCH OR

SOUTHERN PINE

o The entry under lOd nails should be corrected from 3/8 " to 5/8 "

.

o Revise Footnote 1 as follows: ^ Space nails 10 inches on center for floors

and 12 inches on center for roofs along intermediate framing members . Allowable shear values for nails in framing member of other species set

forth in Table 8. 1A NDS (REF. 1) shall be calculated for all grades by

multiplying the values for nails in STRUCTURAL I by the following factors : Group III, 0.82 and Group IV, 0.65 .

o Change the wording under the column heading "BLOCK DIAPHRAGMS" to read:

Nail spacing at diaphragm boundaries (all cases) , at continuous panel

edges parallel to load (Cases 3 and 4) and at all panel edges (Cases 5 and 6)

FINAL BALLOT: _5 YES

NO

ABSTAIN

DID NOT VOTE

COMMENT ON PROPOSED CHANGE:

This set of editorial changes is necessary to make Table 9-1 agree with

Table No. 25-J of the 1979 Edition of the Uniform Building Code.

17
REVIEW AND REFINEMENT OF TENTATIVE SEISMIC PROVISIONS

PROPOSED CHANGE

TECHNICAL COMMITTEE: #7, Wood COMMITTEE ITEM NUMBER:

ATC-3-06 SECTION REFERENCE: Table 9-^2

Revise the table as shown on the attached sheet.

FINAL BALLOT: 5 YES

NO

ABSTAIN

DID NOT VOTE

COMMENT ON PROPOSED CHANGE:

The table was updated to agree with Table No. 25-K of the 1979 Edition of

the Uniform Building Code. This is primarily an editorial change involving

the re-arrangement of columsn with no changes in the numbers in the table.

The previously omitted allowable shear value (200) for siding attached with

8d nails at 4 inches on centers was inserted r

18
TABLE

NO.9-2

-ALLOWABLE

SHEAR

FOR

WIND

OR

SEISMIC

FORCES

IN

POUNDS

PER

FOOT

FOR

PLYWOOD

SHEAR

WALLS

WITH

FRAMING

OF

DOUGLAS

FIR

LARCHiOR

SOUTHERN

PINE 1 |

INCH

•»•mm

r*

O—

O 1 r*\ | o Q | w-> ^ 1 >r if • 1 • - '*+ * * 5* 1 -: o* ; • l 2*1 * »• 1 —E £ J'*

52;-'

gt!?|

S- st • -1 ji O

O 1 ^ 3 1 1 wo o o <-l —

PI Tj

S3 | f. TT 1 o o . r-~ oc PI ro - ?: 25 % r-i rsg^ - S 30 | rs ' JC— S | pi ' i ?§

M • « Sc 2 ,

•• • 2 « sil- * U «J

T3 T3 "2 I

T3 ^ * S 1 ' sS- 

— “ M «• c £

-li X c#

do

O

c»Xi •m

r»

>" ' o o bn- O

OOGm rr ^ r- SS ^ ! • O 1 c

ft_ 1 « ^ j c. o , v W < o lio ^ “ •

C.

m

4.

C ^ C

o; 2 \ o b o W~1 1-^1 pTT K

O<N

QO<^i ! . 99r (3^ ^ o bo

rM r*m ^^ S§

ao* ( w* ;5. X1

4* o b o 2 PIS c b -r p> = !:_ m • r Si-5s * O 1ft 3SS T3 T3 TJ

vO 30

O

N J-

»cc

^r:

53

u

>C ac

_

w « a “ - «s

— =!*!: Iso.s — — “ *J x^*- + C

;* xk;?

X

1;S=: I f ‘J c — o ^ — — 1«S»- « >C jC

r ' fV -

'* om

%sooo*m

•i 4k <

OCD6DX

h*to

C

l), c

c. STRUCTURAL

II

and

other

gtadet

covered

m

l*

liC

Standard

No.

25-9

Plywood

Panel

Siding

in

Grades

C.overetl

in

l)BC

Standard

No

25-9

». c c U U

<J§ §

II

•12 5 Z C > -3 W o ° 3 o 2 5 2

j; * o G. T3 C ~ « * i ao ^ 0 - 1 i 22 -T3

*> 2 = s

*—Ho H,^o - V T ; u a o ^ X - .a 2 - .c

-= if rj

hi c 3 s fc $ -* E c

•3 5 

m_ -o -q ° c c

«• £ o ^ j — C ** W - -C | C 55 f i w o 2=o coC£ * C

i* £2 “ £C E

-a

p«

ui \

<S) -J Q £ 0 -3 — b 1 -

-3

r < ^

CO T3C - c« SiH D c I- _ V. U c 5 -i o <5 £ 6

J*5 o t . N O E

w* * C —

-O * 6 * b ^ e s ? c E 3 = E 5 i c w o 2 b 3 s ? c -- 3 >c » 3 £E

T3 - b1 £ b i c H Z S

-o )

>s

>* 2 c* = b£ as — E TM ” »

-3

JZCu£5 % l — -o 3 3 y 5 £ 3 * i § ?

C. 2

Q. *•

-%

wJ 5 ? w

W%

U

J - > S' — >V 2 a

j=

—z m * * -c

-9

C

CL3CO ^3

<£3

T3 * W > C o w

-C ^ r

19
REVIEW AND REFINEMENT OF TENTATIVE SEISMIC PROVISIONS

PROPOSED CHANGE

TECHNICAL COMMITTEE: #7, Wood COMMITTEE ITEM NUMBER: 13

ATC- 3-06 SECTION REFERENCE: 1.3.1

Modify the last line to read ’’conventional light timber construction as permitted in Section 9.5^."

FINAL BALLOT : 3 YES

1 NO

ABSTAIN

1 DID NOT VOTE

COMMENT ON PROPOSED CHANGE:

The revision subjects one- and two-story wood frame dwellings, not over

35 feet in height and located in areas having Seismicity Index 3 or 4,

to the requirements of Seismic Performance Category C (Section 9.5). As was indicated by the person not voting, the intent of the change is not

clear. The negative voter was strongly opposed to this change in that

he felt the provisions of Section 9.7 as presently required are more

than adequate to assure a safe building.

20
REVIEW AND REFINEMENT OF TENTATIVE SEISMIC PROVISIONS

PROPOSED CHANCE

TECHNICAL COMMITTEE: #7, Wood COMMITTEE ITEM NUMBER: 14

ATC- 3-06 SECTION REFERENCE: 14*6

Add to the reference documents: 1) Plywood Design Specification, 1978, APA

and 2) Plywood Diaphragm Construction 1978, APA.

FINAL BALLOT: _5 YES

NO

ABSTAIN

DID NOT VOTE

COMMENT ON PROPOSED CHANGE:

This is an editorial change.

21
3.0 Committee Records

3.1 Minutes of Meetings

The minutes of the only meeting of the committee, held on December 11, 19879,

follow this page.

22
Minutes of First Meeting

Technical Committee 7 : Wood

Review and Refinement of Tentative Seismic

Provisions (ATC 3-06)

The first meeting of Technical Committee 7 was held on Tuesday, December 11,

1979 at the National Bureau of Standards. The meeting was called to order

at about 12:10 p.m. by Acting Chairman Charles Yancey. The following

members were in attendance:

Name Affiliation

Robert Hewett

Dave Gromala

Daniel H. Brown

Edwin G. Zacher

Charles Yancey

Roy G. Johnston

National Forest Products Association

U, S. Forest Products Laboratory

American Plywood Association

Applied Technology Council

National Bureau of Standards

Building Seismic Safety Council

It was announced that the American Society of Civil Engineers had not

yet named a representative to Committee 7. Mr. Thomas Brassell, the

committee representative from the American Institute of Timber Construction

and Mr. Marco Venturino, the committee representative from the Interagency

Committee on Seismic Safety in Construction, were not present. Mr. William

Kirkland was a visitor at the meeting.

The first agenda item was the selection of a permanent committee chairman

from among the voting members. Mr. Daniel Brown was nominated and unanimously elected as chairman. The committee also elected Mr. Robert Hewett

to serve as vice chairman. Mr. Brown chaired the remainder of the meeting.

The next action was the selection of a representative to Technical Committee #2 (Structural Design). Mr. Edwin Zacher was tentatively selected

pending confirmation that the selection of a non-voting member on Committee 7 as representative to Committee 2 was permissible. Dr. Edward Pfrang

of the National Bureau of Standards was subsequently questioned on this committee

action and he indicated that since the wood industry representatives were

in agreement on the selection that it would be permitted to stand.

The committee then discussed the projected number of days required for

the February Public Meeting. It was the general feeling of the members

23
that a one-day meeting should be sufficient. The next meeting was scheduled for Friday, February 22 in San Diego, CA. Mr. Hewett volunteered to secure a meeting place and to notify the committee's secretary

as to the arrangements.

In the remaining time before lunch, discussion was initiated on some of

the concerns of the Wood Committee. Mr. Zacher led the discussion by

identifying the following items of concern: a) orthogonal connection

provisions, b) R and <j> factors and c) computation of the period of

buildings with relatively flexible diaphragms according to the ATC 3-06

provisions. It was felt that the last item will impact on the deliberations of Technical Committee 2.

The committee broke for lunch at 1:00 p.m. and reconvened at 2:00 p.m.

Discussion continued on the previously-mentioned areas. Mr. Brown

indicated that he had sent to Mr. Zacher some comparative diaphragm

designs, generated by his interpretation of some of the wood provisions

in ATC 3-06. Mr. Zacher commented on Mr. Brown's analyses and also

circulated copies of some comparisons of shear wall design that he had

prepared while reviewing both the Uniform Building Code (1973 and 1976

editions) and the ATC 3-06 provisions. Mr. Hewett raised a number of

prepared questions with Mr. Zacher and in so doing generated a good deal

of discussion on factors and on the interpretation of the provisions

as they apply to conventional light frame construction. Mr. Hewett indicated that some of his questions and concerns would be translated into

proposals for revisions. All individual proposals for revision are to

be sent to the secretary, Charles Yancey, and they will be immediately

transmitted to Mr. Zacher, the ATC representative.

Regarding the announcement of the February Public Working Session, it was suggested that there should be some provision for obtaining a written

reply from the people who intend to attend a given session.

There being no further business, the committee adjourned at about 3:45 p.m.

Respectfully submitted,

0 /

Charles Yancey

24
3.2 Roster

COMMITTEE 7: Wood

American Institute of Timber Construction

Mr. Thomas E. Brassell

Vice President of Technical Services

American Institute of Timber Construction

333 West Hampden Avenue

Englewood, CO 80110

Phone: 303-761-3212

American Plywood Association

Mr. Daniel H. Brown (Chairman)

American Plywood Association

P. 0. Box 11700

Tacoma, Washington 98411

Phone: 206-565-6600

Interagency Committee on Seismic Safety in Construction

Mr. Marco F. Venturino

Supervisor, Structural Engineering

Western Division

Naval Facilities Engineering Command

P. 0. Box 727

San Bruno, CA 94066

Phone: 415-877-7340

National Forest Products Association

Roderick B. Buchan

National Forest Products Association

Forest Industries Building

1619 Massachusetts Avenue, N.W.

Washington, D.C. 20036

Phone: 202-797-5882

25
Committee 7 (continued)

United States Forest Products Laboratory

Mr. Lawrence A. Soltis, Engineer

U.S. Forest Products Laboratory

P. 0. Box 5130

Madison, WI 53705

Phone: 608-264-5600

Applied Technology Council

Mr. Edwin G. Zacher (representative to Committee 2

H.J. Brunier Associates Structural Design)

55 New Montgomery

Suite 608

San Francisco, CA 94105

Phone: 415-781-0370

Building Seismic Safety Council

Mr. Roy G. Johnston

Brandow & Johnston Associates

1660 W. 3rd Street

Los Angeles, CA 90017

Phone: 213-484-8950

National Bureau of Standards

Mr. Charles Yancey

Secretariat

Tentative Seismic Provision Project

Committee 7: Wood

National Bureau of Standards

Rm. B-168, Bldg. 226

Washington, D.C. 20234

Phone: 301-921-2137
3.3 Selected Committee Correspondence and Applied Technology Council Comments

Exhibit A

li Jan. 18 memorandum to committee from secretariat

1 Exhibit B March 31 ATC response to comments from TC 9.

Exhibit C May 6 memorandum announcing telephone canvass.

Exhibit D May 6 memorandum to secretariat of TC 9.

Exhibit E May 7 ATC response to comments from Dan Brown.

Exhibit F May 27 transmittal of letter ballot.

Exhibit G May 29 memorandum to secretariat of TC 9.

27
Exhibit A

/ V r UNITED STATES DEPARTMENT OF COMMERCE

National Bureau of Standards

Washington. D.C. 20234

*r4TtM O*

January 18, 1980

To Members of Technical Committee 7: Wood

Thomas E. Brassell

Daniel H. Brown (Chairman)

Marco F. Venturino

Dave Gromala

Edwin G. Zacher

Roy G. Johnston

Robert Hewett

Dear Member:

This is to inform you that the only comment I have received so far

on the chapter pertaining to Wood in ATC 3-06 was submitted by

Daniel H. Brown of the American Plywood Association in his letter

dated January 4, 1980. This material has already been distributed.

I will keep you informed as additional comments come in.

Sincerely,

unarxes xancey, secretary

Committee 7: Wood

cc: E. V. Leyendecker

Edward 0. Pfrang

Roland Sharpe
Exhibit B

H. J. BRUNNIER ASSOCIATES

STRUCTURAL ENGINEERS

55 NEW MONTGOMERY STREET - SUITE 608 - SAN FRANCISCO. CALIFORNIA 94 105 - 415 781-0370

Mr. Charles Yancey, Secretary

Technical Committee No. 7 fl Tentative Seismic Provisions Project

Room B-168, Building 226

National Bureau of Standards

Washington, D.C. 20234

Dear Charles

This is in response to the memorandum from Patrick W. Cooke.

1. The double plate requirement applies only to conventional light timber construction "which require no

engineering analysis". A single plate could be used

in an engineered construction. The control necessary

to align horizontal and vertical members implies

that the system is engineered and, therefore, single

top plates could be used and splice details to

provide adequate continuity or continiuty equivalent

to a four foot lap splice of a double plate should

be provided.

2. This stance is the opposite of the stance taken by

industry members of Group 7 who wanted to reduce the

requirement. My previous response on this problem

adequately answers this comment.

I have not sent this response to the committee.

H. J. BRUNNIER 1082 • 1971

H. C. POWERS

H. L. LYELL

C. D. DE MARIA

S. E. TEIXEIRA

A. P. STEVENS

March 31, 1980

Very truly yours

"Structural Engineer

29
Exhibit C

UNITED STATES DEPARTMENT OF COMMERCE

National Buraau of Standards

Washington. D C. 20234

May 6, 1980

To Members of Technical Committee 7: Wood

Tentative Seismic Provisions Project

Daniel H. Brown, Chairman

Marco F. Venturino

Thomas E. Brassell

David Gromala

Dear Member:

In a letter dated 24 March 1980, I sent you a package containing two recom- mendations from Technical Committee 9. To facilitate the resolution of the

comments by Messrs. Johnson and Fuller in time for the June 5-6 meeting of

the Coordinating Committee, I will be conducting a telephone canvass of the

members of Technical Committee 7. In this regard I am enclosing a copy of

the response of Mr. Edwin Zacher to the comments in question. Please

review Mr. Zacher' s response as well as the original comments and formulate

an opinion as to what changes, if any, to Chapter 9 of ATC 3-06 are warranted.

I will then call you in about a week from the date of this letter to

record your position. The results of this poll will be forwarded to

Mr. Daniel Brown, Chairman of Technical Committee 7.

Thank you for your cooperation.

it. Charles W. C

Technical Committ

. tancey'. Secretary

mmittee 7: Wood ^

Attachment

cc: Edwin G. Zacher

William Kirkland

E. V. Leyendecker

Edward 0. Pfrang
Exhibit D

May 6, 1980

Memorandum for Patrick W. Cook*, Project Leader

Building Rehabilitation Technology

From: Charles V. C. Yancey

Structurea and Materials Division

Subject x Bevies Consents of ATC Technical Co—lttee 9 Belatlve To Technical

Coonittee 7 ....

Attached Is a copy of the response of Mr. Edwin G„ Zacber to the two comments

hy nesbers of Technical Coonittee 9, as cited la your snorndw to as dated

10 March 1960. Mr. Zachar Is the ATC representst1ve on TC 7 and as such le

quite familiar with tha background to end Intent of the ATC provisions In

Chapter 9 (Mood). Whereas I have seat e copy of your neaorandum (with

attachment) to each member of TC 7* X have neither sent them e copy of

Mr. Zacber's latter dated 31 March 1980 nor polled their response. Therefore. 1 cannot nor Inform you of the final dasposition of these comments

.

Technical Coasdttaa 9 will be notified ea to the decisions reached by

TC 7. prior to the Jane 5-4 masting of the Coordinating Committee.

V/. Attachment
Exhibit E

H. J. BRUNNIER ASSOCIATES

STRUCTURAL ENGINEERS

55 NEW MONTGOMERY STREET . SUITE 508 - SAN FRANCISCO. CAUFORNIA 94105 - 415 781-0370

H. J. BRUNNIER 1B82 - 1971

H. C. POWERS

H. 1_ LYELL.

C. D. DE MARIA

S. E. TEIXEIRA

A. P. STEVENS

May 7, 1980

Mr. Charles Yancey, Secretary

Technical Committee No. 7 Tentative Seismic Provisions Project

Room B-168, Building 226

National Bureau of Standards

Washington, D.C. 20234

Dear Charles:

This is in response to the comments from Dan Brown under his cover letter of April 25, 1980. The item numbers coincide with those on his list.

1.3 As noted in my original comment the 0 factor charge was dependent on possible actions in other committees, especially

Committee 2. At this point there seems to be no move to

change the design force sections and the 0.85 0 is appropriate.

1.4 The existing sentence of 9.5.3, without the heading, should

be made the new first sentence of 9.6.3.

1.5 Section 9.7.1 can be modified as follows: provided at

not over 6 feet on center for buildings two stories, or 20

feet, or less in height and at not over 4 feet on center

for buildings over this height but three stories, or 35 feet

or less in height .

1.6 This reference should be to Section 9.5 but the phrazing

& 2.1 should be modified to read as follows: Conventional

Light Timber Construction as permitted in Sec. 9.j>. Add

the following to the third sentence of Section 9.7.1:

" studs unless specifically excepted in Sec. 9.7.3 . Add the following sentence to Section 9.7.3B: " Blocking

need not be provi ded at horizontal joints ". These accomplish

the intent of Dans comments. The seven diameter embedment

requirement is more consistent than a specified length.

UBC has a conflict between Sec. 2907(c) and Table 26-G.

I suggest, however, for the sake of simplification, that we make the embedment 8 diameters: 4 inches for 1/2 inch bolt,

5 inches for 5/8 inch bolt, etc.

32
Exhibit E

H. J. BRUNNIER ASSOCIATES

STRUCTURAL ENGINEERS

May 7, 1980

Mr. C. Yancey, Secretary

response to comments

from Dan Brown

page two

2.4 Modify the language proposed in my previous response

regarding Section 9.5.3 as follows: in a joint of a frame or similar component of the seismic resisting

system the total .

I have not sent this response to the committee.

Very truly yours

EGZ/ng

33
diibit F UNITED STATES DEPARTMENT OF COMMERCE

National Bureau of Standards

Washington. D.C. 20234

May 27, 1980

MEMORANDUM FOR Members of Technical Committee 7 : Wood

Thomas E. Brassell

Daniel H. Brown

Roderick B. Buchan

David Gromala

Marco F. Venturino

From: Charles W. C. Yancey, Secretary

Committee 7: Wood

Subject: Suggested Changes to Chapter 9 of ATC 3-06

All of the suggested changes to Chapter 9 of the ATC 3-06 document have

been compiled and are enclosed. You should refer to letters from

Mr. Dan Brown (dated 4 January and 25 April 1980) and Mr. Ed Zacher

(dated 1 February and 31 March) for the applicable background material.

Also, I have enclosed a copy of a letter from Mr. Zacher, dated 7 May,

which you have not previously been sent. You are asked to vote on each of the changes. Please indicate your vote (Affirmative, Affirmative

with Comment, or Negative) in the right hand margin adjacent to each

item. You are asked to make your comments directly on the orange copy

and return it to Dr. E. V. Leyendecker at:

In view of the fact that the results of this ballot should be discussed

at the June 5 and 6 meeting of the Coordinating Committee, your immediate

response is requested. Although the allotted review time seems quite

short, practically all of the recommended changes were listed in

Mr. Zacher' s letter of 1 February 1980. As a time expedient, I will

call you next week to record your vote. Then, the written ballot can

be sent to Dr. Leyendecker as mentioned above.

Enclosures

cc: Edwin G. Zacher Roy G. Johnston

E. V. Leyendecker Roland Sharpe

Edward 0. Pfrang William Kirkland

Room B168 Building 226

National Bureau of Standards

Washington, DC 20234.
V.1

Exhibit G

May 29, 1980

MEMORANDUM FOR Patrick W. Cooke, Project Leader

Building Rehabilitation Technology

From: Charlee W. C. Yancey

Structures and Materials Division

Subject: Review Comments of ATC Technical Committee 9 Relative to

Technical Committee 7

I call your attention to my memorandum to you dated May 6, 1980. As a follow-up, I sent a copy of Mr. Edwin Zacher's letter, dated March 31, 1980,

to each member of Technical Committee 7. and then polled their response

via telephone. The committee members were in agreement with both of

Mr. Zacher's comments. With reference to Mr. Zacher's second comment,

it was the opinion of Mr. Daniel Brown (American Plywood Association)

that the anchor bolt spacing specified in 9.7.1(A) could be extended

to 6 feet in buildings not over 20 feet high. In fact, one of the suggested changes presently being ballotted within Committee 7 provides

for up to 6-feet spacing of anchor bolts in buildings "two stories,

20 feet, or less in height." I am enclosing a copy of the page on which

this suggested change is Included.

In summary, it Is concluded that Mr. David Johnson's comment on the need

for expanding the guidelines for top plates in 9.7.1(B) will receive no further consideration by Technical Committee 7. Also, it is inferred

from the fact that Committee 7 is now voting on a suggested modification

to 9.7.1(A) which would effectively reduce the anchorage requirements that

Mr. Robert Fuller's suggestion of strengthening the anchorage requirement

will not be sustained. •• •- Enclosure
Exhibit G

(B) PLYWOOD SHEAR PANELS ~ ”—" — -

Remove this subsection and transfer It to Section 9.6.3.

Section 9.6.3 DIAPHRAGM LIMITATIONS

The existing sentence In subsection 9.5.3 (B), without the heading, should

become the first sentence In Section 9.6.3.

Section 9.7.1 WALL FRAMING AND CONNECTIONS

'

(A) ANCHOR BOLTS - -

Section 9.7.1 can be modified as follows: -—provided at not over 6 feet

on center for buildings two stories, 20 feet, or less in height and at not

over 4 feet on center for buildings over this height but three stories/ or 35 feet or less in height . Anchor bolts shall Have a minimum embedment of

8 diameters.

Section 9.7.1 %

(C) BOTTOM PLATES

Delete the word “stud" at the end of the sentence and add the following

" . .

.

studs unless specifically excepted in Section 9.7.3. "

Section 9.7.3 ACCEPTABLE TYPES OF WALL SHEATHING

(B) PLYWOOD

Add the sentence: "Blocking need not be provided at horizontal joints."

Table 9*1 - Chanqe the table heading to read: ALLOWABLE SHEAR IN POUNDS

PER FOOT FOR HORIZONTAL PLYWOOD DIAPHRAGMS WITH FRAMING OF DOUGLAS FlftLARCH 6R SOUTHERN PINE"1

'

• The entry under lOd nails should be corrected from 3/8" to 5/8"

• Revise Footnote 1 as follows: ^ Space nails 10 Inches on center for

floors and 12 inches on center for roofs along intermediate framing

members. Allowable shear values ?or nails in framing member of otner

species set forth in Table 8.1 A (REF, l) shall be calculated for"

*

all grades by multi plyingthe values for nails in STRUCTURAL \ by the

following factors: Group III, 0.82 and Group IV, 0.f>5 .

• Change the wording under the column heading "BLOCK DIAPHRAGMS" to

read : Nail spacing at diaphragm boundaries (all cases), at continuous

panel edges parallel to loacT (Cases 3 and 4) and at all panel edges

(Cases 5 and 6) .

• Table 9-2

Revise the table as shown on the attached sheet.

36
NBS-1 14A (REV. 0-78)

U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO. NBSIR 80-2111-7

2.Gov*t Accession No. 3. Recipient's Accession No.

' |

4. TITLE AND SUBTITLE

REVIEW AND REFINEMENT OF ATC 3-06 TENTATIVE SEISMIC PROVISIONS

Report of Technical Committee 7 : Wood

5. Publication Date October 1980

6. Performing Organization Code

7. AUTHOR(S)

Charles W. C. Yancey

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, DC 20234

10. Project/Task/Work Unit No.

11. Contract/Grant No.

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

Federal Emergency Management Agency

Washington, D.C. 20472

13. Type of Report & Period Covered Final

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

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

IS. 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 com- munity. 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 recom- mendations and records of the commitee charged with review of the provisions for the

design and detailing of wood structures. The committee made 14 recommendations for

revision to the TENTATIVE PROVISIONS. 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.

17* KEY WORDS (six to twelve entries ; alphabetical order; capitalize only the first letter of the first key word unless a proper name;

separated by semicolons)

Building; building codes; building design; earthquakes; engineering; standards;

structural engineering; wood

18. AVAILABILITY [X] Unlimited 19. SECURITY CLASS 21. NO. OF

(THIS REPORT) PRINTED PAGES

1 1 For Official Distribution. Do Not Release to NTIS X

UNCLA' SIF IL

[ Order From Sup. of Doc., U.S. Government Printing Office, Washington DC

20402, SD Stock No. SN003-003-

20. SECURITY CLASS

( THIS f AGE)

2?. Price

fx] Order From National Technical Information Service (NTIS), Springfield, VA. 22161 UNCLASSIFi J usco <-oc
' inai—

r