ML19345B201
| ML19345B201 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 11/03/1980 |
| From: | Daltroff S PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| IEB-80-11, NUDOCS 8011260331 | |
| Download: ML19345B201 (37) | |
Text
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PHILADELPHIA ELECTRIC COMPANY 2301 MARKET STREET P.O. BOX 8699 PHILADELPHI A. PA.19101 SHIELDS L. DALTROPP sLacts c Pa CTION November 3, 1930 Re: Docket Nos.: 50-277 50-278 IE Bulletin 80-11 G8 b.
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Mr. Boyce H.
Grier, Director "4
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United States Nuclear Regulatory Commission A
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631 Park Avenue cn King of Prussia, PA 19406
Dear fi r. Grier:
This is in response to your letter of :tay 8,
- 1980, which forwarded IE Bulletin 80-11.
Our letter dated July 2, 1980, contained responses to items 1,
2a, and 3 of the Bulletin.
This is an interim response to item 2b of the Bulletin, reporting progress to date and informing you of our schedule for completion of wall re-evaluation.
The actions requested in item 2b of the Bulletin and our responses are listed sequentially below.
Action to be Taken by Licensee:
2.b.(i)
Describe, in detail, the function of the masonry walls, the configurations of these walls, the type and strengths of the materials of which they are constructed (mortar, grout, concrete and steel), and the reinforcement details (horizontal steel, vertical steel, and masonry ties for multiple wythe construction).
A wythe is considered to be (as defined by ACI Standard 531-1979) "each continuous vertical section of a wall, one masonry unit or grouted space in
' thickness and 2 in. minimum in thickness."
8021260- N
Mr. Boyce H.
Grist Page 2
Response
The function of the masonry walls was described in Appendix A of our letter of July 2, 1980 as either shielding walls or fire resistance walls.
Concrete masonry walls are not used as shear valls at Peach Bottom Atomic Power Station.
The configuration of the masonry walls, i.e.,
the length and the height, varies depending on its function althin the plant and the nature of the construction abutting the ends or the tops of these walls.
Wall thicknesses range from eight inches to forty-eight inches depending on requirements for shielding or fire resistance.
Vertical reinforcing has been placed in single wythe walls and in exterior wythes of multiple wythe walls.
In partition and/or fire walls, cells in which vertical reinforcing is placed are filled with grout.
In shield walls, all cells are grout filled.
The space between exterior wythes in multiple wythe walls is filled with concrete or concrete brick.
Reinforcement is provided in horizontal joints to control shrinkage cracking of the walls and bond beams are provided at intervals.
At wall intersections, all horizontal reinforcing is placed to provide continuity at these interseccions.
Where required, horizontal restraint is provided at the top and/or sides of tSe block walls.
At the base of the walls, restraint is provided by steel angles bolted to the floor or by expansion bolts projecting into the block cells at the same spacing as the vertical reinforcing.
The materials used in the construction of masonry walls and their strength requirements are as follows:
1.
Concrete Block ASTM Specification C90-66, Grade U-1 2.
Mortai-ASTM Specif; cation C-270, type N, minimum compressive strength 750 psi at 28 days 3.
Grout (Concrete)
Minimum compressive strength 2000 psi at 28 days 4.
Reinforcing steel ASTM Specification A-615, Grades 40 and 60 The reinforcing placed in the masonry walls consists of the following:
1.
Vertical reinforcing Deformed bars, ranging in size from
- 4 to #8, spaced at 24" to 32",
i depending on requirements.
Mr. Boyce H. Grier Page 3 2.
Horizontal reinforcing Bond beam reinforcing consists of
- 4-or #5' deformed bars' spaced at 40".
Bond beams contain either two or four bars.
In addition, #8 gage ladder type reinforcing is placed in the horizontal joints spaced at 16".
3.
-Masonry ties
=In walls of multiple wythe construction, #10 gage wall ties are -placed at-a spacing of 48" horizontally and vertically.
2.b.(ii) ' Describe the construction practices employed in the construction of these walls and, in particular, their adequacy in preventing significant voids or other-weaknesses in any mortar, grout, or concrete fill.
Response
To assure proper construction practices, requirements were defined in the project specifications for masonry walls.
While work was in progress and upon complotion of wall construction, inspections were made to assure' proper workmanship in accordance with the drawings and specifications.
To assure conformance with strength requirements, appropriate tests were performed on specimens of concrete masonry units, mortar, grout fill, and the reinforcing bars.
Documentation of the above inspections and tests are maintained in.the project file.
2.b.(iii) The re-evaluation report should include detailed justification for the' criteria used.
References to existing codes or test data may be used if applicable for the plant conditions.
The re-evaluation should specifically address the following:
l l
(a)
All' postulated loads and load combinations should 4
be evaluated against the corresponding re-evaluationLacceptance criteria.
The re-evaluation should consider the loads from safety and non-safety-related attachments, differential floor displacement and thermal effects-(or detailed
^
justification that these can be considered self limiting and cannot induce brittle failures), end-theLeffects of any' potential cracking under I
dynamic loads.
Describe'in detail the methods used to account for these factors in the re-evaluation and the adequacy of the acceptance criteria for both in plane and out-of plane loads.
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e-Mr. Boyce H.
Grier Page 4 (b)
The mechanism for load transfer into the masonry walls and postulated failure modes should be reviewed.. For multiple wythe walls in which composite behavior is relied upon, describe the methods and acceptance criteria used to assure that these walls will behave as composite walls, especially with regard to shear and tension transfer at the uythe interface 2.
With regard to local loadings such as piping and equipment support reactions, the acceptance criteric should assure that the loads are adequately transferred into the wall, such that any assumptions regarding the behavior of the walls are appropriate.
Include the potential for block pullout cnd the necessity for tensile stress transfer through bond at the wythe interfaces.
Response
It has been determined that a total of 86 concrete masonry walls at Peach Bottom Atomic Power Station have safety related systems r
either attached to, or in the proximity of these walls.
For the purposes of re-evaluation, similar walls were segregated into groups according to thickness, span, loading, configuration, boundary conditions, and location in the plant.
Loads from non-safety related systems attached to these walls are included in the analysis.
One wall was selected from each group as conservatively representative of that group.
The attached Appendix A" is-a summary of the walls selected for analysis, the walls they are representative of, and the current re-evaluation status.
Analysis has been completed on 14 walls, which are representative of 56 of the 86 walls subject to re-evaluation.
All of the walls represented by the analysis to date are structurally adequate when compared to the re-evaluation criteria.
Composite action of multiple wythe walls has not been necessary for the structural adequacy of the walls re-evaluated to date.
The Re-evaluation Criteria and the justification for that criteria are attached as Appendices B and C, respectively.
The Re evaluation Criteria' defines the design allowable stresses used in'the analysis, and specifies the loads and load combinations in accordance with the FSAR (including Supplement No. 2) and the Project Design Criteria.
It identifies macerials used in the actual wall construction, and specifies structural considerations to be used in the analysis, including structural response, boundary conditions, inter-story drift effects, in plane and out-of plane. loading, and shear strength of collar joints.
The mechanism for load transfer into the masonry walls consists of either through-bolts or expansion anchors, depending on the magnitude of applied loads.
Preliminary investigation of potential block pull-out indicates that the applied loads would w
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M r '. Boyce H.
Grier
.Page 5 not cause a failure of this type, however, detailed verification will be provided in our final report.
j Our July 2, 1980 response identified walls which, based on a review of drawings, do not have-safcty related systens or equipment either attached to ther. or in proximity.
We have made a visual, walk-through survey of these walls, and have confirmed the accuracy of'that drawing review.
1 A final report will be submitted-by May 4, 1981 and will contain a complete response to all the requirements of the Bulletin.
Very truly yours,
/
/,.
i
{YCLN-ls-
, v Attachments:
Appendix A l
Appendix B Appendix C cc: United States Nuclear Regulatory Commission Office of Inspection and Enforcement Division of Reactor Operations Inspection Washington, DC 20555 9
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i COMMONWEALTII 0F PENNSYLVANIA :
ss.
COUNTY OF PHILADELPilIA S.
L.
Daltroff, being first duly sworn, deposes and J
says:
That he is Vice President of Philadelphia Electric Company; that he has read the foregoing response to IE Bulletin 80-11 and knows the contents thereof; and that the statements and matters set forth therein are true and correct to the best of his knowledge, information and belief.
()k d'
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6 Subscribed and sworn to dNb day before me this
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g >cndix "A" G00156 Sunmary of Walls Selected for Re-evaluation No. of Walls Selected Re-evaluation Wall Wall Walls
. Serial No.
for Analysis Status Thickness
_ Represented Represented 1
40.2 Couplete 8"
40.1-40.26 26 2
25.1 Couplete 8"
25.1-25.2 2
3 68.2 Conplete 8"
68.2-68.3 2
4 68.4 Conplete 8"
68.1,68.4 2
5 76.6 Couplete 8"
76.6,8,10;410.6,8,10 6
6 76.9 Couplete 8"
76.7,9;410.7,9 4
7 C-86.1 Couplete 8"
C-86.1,2 2
8 32.3 Caplete 12" 32.3 1
9 32.5 Conplete 12" 32.5 1
10 32.4 Conplete 12" 32.4 1
11 418.10 Pending 12" 418.10,11;102.8,9 4
12 532.1 Conplete 12" 532.1,2,3 3
3 56.1 Pending 12" 56.1
~
l 14 15.1 Conplete 16" 15.1,2 2
15 16.3 Pending 18" 16.3 1
16 32.1 Pending 18" 32.1,2 2
17 16.1 Pending 24" 16.1,2 2
18 78.3 Pending 24" 78.3 1
19 32.10 Pending 24" 32.10,11,12 3
20(a) 71.1 Couplete 30" 71.1 1
20(b) 68.5 Pending 30" 68.5 1
21 40.27 Pending 30" 40.27,28,29,30 4
22 406.2 Pending 36" 406.1,2;45.1,45.2 4
23 406.6 Pending 36" 406.6 1
24 406.9 Pending 36" 45.4,45.6, 406.9,10 4
25 412.1 Pending 39" 87.1,412.1 2
26 410.1 Conplete 48" 75.6,409.7,410.1 3
86 T-93/9:Date Oct. 29, 1980
- v24
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CGU15G APPENDIX B i
CRITERIA FOR THE RE-EVALUATION OF CONCRETE MASONRY WALLS IN RESPONSE TO NRC I&E BULLETIN 80-11 FOR THE PEACH BOTTOM ATOMIC POWER STATION UNITS 2 AND 3 PHILADELPHIA ELECTRIC COMPANY i
BECHTEL POWER CORPORATION
.3an Francisco, CA.
d 10/29[W ISSUED FOR US" h
1 P-199/4 y
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l TABLE OF CONTENTS 1.0 GENERAL 1.1 Purpose 1.2 Scope 2.0 GOVERNING CODE 3.0 LOADS AND LOAD COMBINATIONS l
4.0 MATERIALS 5.0 DESIGN ALLOWABLES l
6.0 ALTERNATIVE ACCEPTANCE CRITERIA i
i 7.0 ANALYSIS AND DESIGN 7.1 Structural Response of Masonry Walls 7.2 Structural Strength of Masonry Walls P-199/4
-ii-Rev. O I
'~
(*Q1g.
CRITERIA FOR TlIE RE-EVALUATION OF CONCRETE MASONRY WALLS 1.0
_ GENERAL 1.1 Purpose This criteria is provided for use in re-evaluat-ing the structural adequacy of concrete block walls as required by NRC I&E Bulletin 80-11, Masonry Wall Design, dated May 8, 1980.
1.2 Scope The're-evaluation shall determine whether the concrete masonry walls and/or the safety related equipment and i
systems sscociated with the walls will perfoca their intended function ander the loads and load coubinations prescribed herein.
Verification of wall adequacy shall include a review of local transfer of load from block into wall, global response of wall, and transfer of wall reactions into supports where response spectra are defined.
Anchor bolts and embedments are not considered to be within the scope of the evaluation.
Unique problems or special cases where higher damping, increased allowables or_ modified criteria and analysis me thods are proposed shall be brought to the attention or the Chief Civil Engineer.
2.0 Governing Code The design allowables,are based on ACI 531-79 (Table 1, P.10)
However, the stresses will also be checked against UBC-1967 (Table 2, P.13).
In case the lower allowables of UBC-1967 govern the Chief Civil Engineer shall be consulted.
Supplemental allowables as specified herein shall be used for cases not directly covered in the governing code.
3.0 Loads and Load combinations The following load combinations shall be used for the analysis of the masonry walls:
1.
D+E 2.
D+E' l
P-199/4 i !
Rev. O
lll87-C-8
'l CO615id 3.
D+W'
'4.
D+E+T 5.
C+E'+ho 6.
D+F 7.
1.05D+1.25P 8.
1.05D+1.0P' 9.
1.05D+1.0T, Where:
i D:
Dead load of structure and equipment plus any other permanent loads E:
OBE loads E': SSE loads W': Tornado loads To: Operating temperature loads Ta: Accident temperature loads F:
Flood loads P:
jet impingement load P': Pressurization load due to high energy line break Load combinations 1 through 6 are obtained directly from the project FSAR.
Load combinations 7, 8 and 9 have been arrived at by following the project design criteria, the i
PBAPS FSAR supplement No. 2, and, the recommendations of the Mechanical / Nuclear group and the Civil Staff.
4.0 MATERIALS The materials used in the masonry wall construction are as follows:-
Reinforced Masonry:
Hollow concrete units of ASTM C90-66 Grade U-l (equivalent of Grade A of UBC-67 and Grade N of UBC-79) and grouted solid are used with ultimate compressive stress f'm as indicated in Tables 1 and 2.
Reinforcing Steel Rebar is ASTM A 615 Grade 40 or 60.
Mortar:
Mortar is ASTM C270, Type N with average compressive strength m of 750 psi at 28 days.
g Shielding Block Wall The shielding wall is heavyweight concrete block and has all cells and cavities between blocks filled with concrete.
Heavyweight con' crete block dry density is 145 pcf.
P-199 Rev. 0
11187~C~U011 l.G?jQG Core Concrete or Cell Grout Core concrete has an average compressive strength f'c as indicated in Tables 1 and 2 (see Note 1 at the end of the Tables).
5.0 Design Allowables 5.1 Design allowables for load combination D+E shall be as follows:
5.1.1 Masonry The allowable tension, compression, shear, bond and bearing stresses shall be as given in Tables 1 and 2.
)
i 5.1.2 Collar Joint l
1 The allowable shear or tension stresses shall be based on testing and shall be the lesser of:
a) 1/2 the lower bound ultimate stress as generally determined by the,mean minus 1.28 X standard deviation b) 1/3 the mean ultimate stress.
5.1.3 Core Concrete or Cell Grout The allowable tension stresses shall be 2.5 x 3/Egr or 0.33 times the modulus of rupture as determined by tests.
5.1.4 Reinforcing Steel The allowable tension and compression stresses shall be as given in Tables 1 and 2.
5.1.5 Secondary Effects (Thermal and Displacement Limited Loads)
Design allowable stresses for load combination D+E+T shall be as given in Tables 1 and 2.
o The same allowable stresses may be used when considering displacement limited loads.
In-plane effects due to interstory drift may be determined by analysis or for confined walls which are bounded (a) top and bottom, (b) bottom-and two sides, or (c) all four sides the in-plane strains (ek /E) shall be limited P-199/4 Rev. 0
~
l
gng:r7-t-go al CC-b,iDo to.001, where 21 in'the relativo displacement batwaon top and bottom of the wall and H is the height of the wall.
Alternatively, for 4'
confined galls dk/H may be limited to 1 + (B/H), provided 0.5 < B/H < 2.5 where B 2000 (B/H)
~~
is the length of the wall.
5.1.6 Seismic and Wind Loadina The 33% increase in allowable stresses for masonry and reinforcing steel due to OBE or wind loadings is not ' permitted except as agreed to with the Chief Civil Engineer.
5.2 Design allowables for load combinations (D+E'),
(D+W'), (D+E'+T ),
(D+F), (1.05D+1.25P), (1.05D+1.0P')
n and (1.05D+1.OT ) shall be as follows:
a 5. 2.'1 Masonry The allowable masonry stresses shall be as given in Tables 1 and 2.
The allowable collar joint shear and tension shall be 1.67 times 4
the values specified in Section 5.1.2.
s 5.2.2 Reinforcing Steel The allowable steel stresses shall be as given in Tables 1 and 2.
5.2.3 Impact and suddenly Applied (Step Pulse) Loads The stresses due to load combination (1.05D+
1.25P) may exceed the allowables of Tables 1 and 2 provided there will be no loss of i
function.of any safety related system.
Consult with the Chief Civil Engineer regarding analytical techniques to be used.
5.2.4 Secondary Effe: cts In lieu of a more rigorous analysis in-plane strains due to the interstory drif t may be limited to the values in paragraph 5.1.5.
5.3 Damping 5.3.1' The damping values to be used shall be as follows:
a)
For uncracked sections use 2% for both OBE and SSE.
bi)
For cracked sections use 4% for OBE and 7% for maximum credible earthquake (SSE).
P-199/4 Rev. 0 9 '
a-
-n
. Higher values may be used as determined by the Chief Civil Engineer on a wall-by-wall basis.
5.4 Modulus of Rupture 5.4.1 The extreme tensile fiber stress for use in determining the lower bound uncracked moment capacity is 6/Ir or 0.8 times the modulus of rupture as determined by test for the core concrete or cell grout, and 2.4 times the allowable flexural tensile stress for masonry (see Tables 1 and 2 ).
5.5 Non-Category I Masonry Walls 5.5.1 Concrete masonry walls not supporting safety systems but whose collapse could result in the loss of required function of safety related equipment or systems shall be evaluated the same as walls that support safety systems.
Alternatively, under the direction of the Chief Civil Engineer the walls may be analytically checked to verify that they will not collapse when subjected to accident, tornado or safe shutdown (design basis) earthquake loads.
5.6 Inspection 5.6.1 Adequate inspection was performed during masonry construction.
Accordingly, the allowable stresses of Tables 1 and 2 are the inspected values as specified in the respective codes.
6.0 ALTERNATIVE ACCEPTANCE CRITERIA E
6.1 Where the bending due to out-of-plane inertial loading causes flexural stresses in the wall to exceed the design allowables given in Table 1 and 2, the wall can be evaluat'ed as follows:
6.1.1 Energy Balance Technique The deflection of the fully cracked reinforced wall subjected to SSE loading may be deter-mined by the " energy balance technique".
If the predicted displacement exceeds three times the yield displacement, the resulting displacement P-199/4 Rev. 0 e
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. =,
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--,-y,y,-yy- -,..-,, --
-p--g-g-s,
-y-
-9
-,y g-
,-7gg,9_yy..,y
F; '? fg 54?,
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chall be multiplied by a factor of 2 and a determination made as to whether such factored displacement would adversely impact the function of safety related systems attached and/or adjacent to the wall.
In any event, the midspan displacement shall be limited to five times the yield displacement, and the masonry compression stresses shall be limited to 0.85f'm based on a rectangular stress distribtion.
6.1.2 Arching Action The resistance of the wall to out-of-plane forces may be determined by assuming that a three hinged arch is formed after flexural cracking.
Due consideration shall be given to the rigidity of the supporting elements and their ability to restrict rotation of the wall about the supports.
The effects of a gap at the supports shall be considered.
The masonry compression stress shall be limited to 0.85 f'm based on a rectangular stress block.
The tensile stresses along the diagonal failure plane in the vicinity of the hinge locations shall be limited to 6 /f'm.
The displacement at the interior hinge of the arch shall not exceed 1/2 of the collapse displacement.
A determination shall be made as to whether a displacement of 2 times the calculated displacement would adversely impact the function of safety-related systems attached and/or adjacenet to the wall.
7.0 Analysis and Design 7.1 Structural Response of Masonry Walls 7.1.1 Equivalent Moment of Inertia (I,)
To determine the out-of-plane frequencies of masonry walls, the uncracked behavior and capacities of the walls (Step 1) and, if applicable, the cracked behavior and capacities of the walls (Step 2) shall be considered.
Step 1 - Uncracked Condition The equivalent moment of inertia of an uncracked wall (It) shall be obtained from P-199/4 Re v. 0 k--
m.,
w.,,.
y-,-,,-
--ggggr m g --
a-transform 9d coction consisting of the block, mortar, call grout and core concrete.
Alternatively' the cell grout and core con-crete, neglecting block and mortar on the tension side, may be used.
Step 2 - Cracked Condition If the applied moment (M a load combination excee8s) due to all loads in the uncracked moment capacity (Mer), the wall shall be considered to be cracke,d.
In this event, the equivalent moment of inertia (I,) shall be computed as follows:
[M M
cr er l
I
+
11 X I e"(*)X l
t er It1 M
I cr r
Y]
- where, Mer = Uncracked moment capacity M
= Applied maximum moment on the wall a
I
= Moment of inertia of transformed section t
Icr = Moment of' inertia of che cracked section f
= Modulus of rupture (as defined in r
paragraph 5.4.1) y
= Distance of neutral plane from tension face If the use of I results in an applied moment e
M which is less than Mer, then the wall shall a
be verified fer Mcr*
For walls in which two-way spans are considered, consult with the Chief Civil Engineer for analytical approaches.
7.1.2 Modes of vibration The effect of modes of vibration higher than the fundamental mode shall be considered.
For this purpose, a modal analysis may be performed.
Alternatively, the it.ertia load on the wall due to its own weight for the fundamental mode may be considered as an P-199/4 Rev. 0 c-E
-m-w y
.n t d>O O
uniform load in lieu of determining an effective mass.
The corresponding bending moment and reaction will account for the higher mode effects.
7.1.3 Frequency Variations Uncertainties in structural frequencies of the masonry wall due to variations in structural properties and mass shall be taken into account.
Significant variables include mass, boundary conditions, modulus of elasticity, extent of cracking, vertical load, in-planc and out-of-plane loads,'two-way action, and composite action of multi-wythe walls.
To account for the effect of frequency variations, it is considered conservative to use the lower bound frequency if it is on the l
higher frequency side of the peak response spectrum.
If the lower bound frequency is on the lower frequency side of the peak, the peak acceleration shall be used unless a more detailed analysis is performed.
These requirements may bg relaxed on a wall-by-wall basis after consultations with the Chief Civil Engineer.
7.1.4 Accelerations For a wall spanning between two floors, the effective accelerations shall be the average of the accelerations as given by the floor response spectra corresponding to the wall's natural frequency.
7.2 Structural Strength of Masonry Walls 7.2.1 Boundary Conditions Boundary conditions shall be determined considering one-way or two-way spans with hinged, fixed or free edges as shown in design drawings.
Conservative assumptions may be used to simplify the analysis as long as due consideration is given to frequency variations.
7.2.2 Distribution of concentrated out-of-Plane Loads o
Two-Way Action Where two-way bending is present in the wall the localized moments per unit width under P-199/4 Rev. 0 l
l
40&-56 a concentrated load can be determined using appropriate analytical procedures for plates.
Standard solutions and tabular values based on elastic theory contained in textbooku or other published documents can be used if applicable for the cune under investigation (considering
?.oad location and boundary conditions).
o Onc-Way Action For dominantly one-way bending, local moments can be determined using beam theory and an effective width of six times the wall thickness.
- However, such moments shall not be taken as less than that for two-way plate action.
7.2.3 Interstory Drift Effects Interstory drift effects shall be derived from the original dynamic analysis.
7.2.4 In-plane an6 out-of-plane Effects The combined effects of in-plane (e.g. seismic) and out-of-plane (e.g., piping) loads shall be considered.
7.2.5 Stress Calculations All stress calculations shall be performed by conventional methods prescribed by the Working Stress Design method and other accepted principles of engineering mechanics.
TSe collar joint shear stress shall be determined by the relationship VQ/Ib for uncracked sections and in the compression zone of cracked sections.
The relationship V/bjd shall be used for collar joints in cracked sections between the neutral axis and the tension steel.
7.2.6 Analytical Techniques In general, classical design techniques shall be used in the evaluation.
Simplified conservative analytical assumptions may be i
used.
However, more refined methods utilizing computer analyses or dynamic analyses may be used on a case-by-case basis.
P-199/4 Rev. O i
~
m Dohn) 11187-C-8011 TABLE 1 1,
I I
I I
Load l
Materials &
l Allowable Stress i1 l Combination l
Stress l
ACI 531-79 (psi)
I l
l Description l
l I
l I
l' I
I I
ID+E l
Masonry:
f', = 1175 (see Note 2) l I
I I
1 l
l l
l l
Flex. Compression 1
0.33f', = 388 l
l 1
1 I
I I
I i
1 l
l 0.225 f'm
[1-(h/40t)3] for walls. I i
1 Axial l
Where:
1 I
l Compression I
f'm = Ultimate compressive l
l l
l strength of masonry = 1175 l
l I
I I
I I
I I
l l
l t
=
wall thickness in inches, 1
I I
I I
l l
1 h
clear height in inches 1
=
1 I
l l
I 11)
Normal to bed joints:
1 1
1 l
a) 0.5/m
= 14 for hollow units. l o
l l
Tension (No Tensioni b) 1.0/m
= 27 for solid or l
o
,l I
Reinforcement)
I grouted units l
I i
12)
Parallel to bed joints in running l l
l l
bond i
l l
l a) 1.0/m
= 27 for hollow units l
o 1
l l
b) 1.5/m
= 41 for solid or i
o l
l I
grouted units l
I I
I I
I I
l l
1 l
Shear with no ll.1/f',= 38 for transverse shear in l I
l Reinforcement I
flexural members.
1 l
l (stirrups) 10.9/ G = 31)'for shear walls - see i
I I
lor I
i i
- 12. 0/f ', d 4 0 s Table 10. 0 of ACI l
1 l
l 531-79 P.16 1
,I I
I I
I l
l l
[
l Shear with 13.0/ F = 103 for flexural members l
l l
Reinforcement 11.5 51 for shear walls See I
=
(
l (stirrups) lor
'rTable 10.1 of ACI l
l l
Stirrups taking 12.0/ G d 45,.531-79 P.16 l
l
[
entire shear l
l l
l 10.25 f'Y
= 294 on full area l
i 1
Bearing 10.375 f
= 441 on one-third area or l m
I I
I less.
I I
I I
I l
l Bond l
NA l
l l
l l
P-199/3 Rev. O
wemm l
l 1
Il 1
Lord l
Materials & Stress l
Allowable Stress l!
I Combination i
Description l
ACI 531-79 (psi) l
'I I
I i
i I
i l
i D+E I
Reinforcing i
l l
Steel:
I i
l' 1
1 I
J l
l l
Tension i
20,000 for 40 grade steel l
l I
I 24,000 for 60 grade steel l
i I
I
,_I I
i i
40% of ASTM specified yield -
1 l
l Compression i
16,000 for 40 grade steel i
I l
l 24,000 for 60 grade steel I
i I
i i
I I
I ID+E+T l
Stresses'for Increase the allowables for I
o l
1 All Materials I
load combination D + E by a l
l I
i factor of 1.3 l
1 I
I i
1 I
I I
I Masonry:
The allowable masonry stresses for load combi-1 I
l nation D + E shall be increased as follows:
1 I
i i
D& E' l
1 l
l 1
l l
Increase Factor l
l D + W' 1
Compression l
1 I
axial:
1 2.0 l
l l
D+E
'+T l
flexural:
1 2.5 I
o I
I i
1 D+F l
Bearing:
1 2.5 l
1 1
i i
l 1
1.05D+1.25P l Shear and Bond:
I 1.67 l
t 1
1 i
1.05D+1.0P' l Tension l
I I
i I
I i
1.05D+1.0T l
No tension rebar l
I a
l 1
tension normal 1
l 1
i l
to bed joints:
1 1.67 l
l 1
1 I
I I
tension parallell l
1 l
to the bed I
1 1
l joints; in run-1 I
I I
ning bond:
1 1.67 l
1 I
I 1
P-199/3
~11-Rev. 0
TABLE 1 (Cont d)
NTO i
I i
I i
I Load I
Materials & Stress l
Allowable Stress 1
I Combination 1
Description I
ACI S31-79 (psi) l I
I I
I I
I I
I I
I ID& E' l
Reinforcing i
I I
steel:
1 1 D+W' l
l 1
1 I
I I D+E '
+T l
Tension l
'J, - Fy, provided lap slice lengths o
I 1
Compression I
and embeCnent (anchorage; develop l
l D+F f
l this stress level.
Allowable bond l
I I
l stresses may be increased by a i
i 1.05D+1.25P l
l factor of 1.67 in determining i
i l
i splice and anchorage lengths.
l l 1.05D+1.0P' l
I
~
l i
I I
I i 1.05D+1.0T, I
i 1
1 I
I I
ceoceo 1.
The core concrete (or cell grout) has average compressive strength f'c of 3800 psi.
2.
From Table 4.3 of ACI 531-79, f'm is interpolated as'1175 psi.
This corresponds to compressive test strength of 3270 psi for the masonry units, based on the net cross-sectional area.
i l
- i P-199/3 Rev. O i
'I I
I
b.I.$G TABLE 2 i
1 1
I I
Load l
Materials &
l Allowable Stress: UBC-67 l
l Combination 1
Stress I
(psi)
I l
l De scripcion l
I I
I
~
I l
I i
i i
l l
i D+E I
Masonry:
f', = 1500 (see note 2) l I
I I
I I
I I
I i
i l
l Flc ;. Compression i
.33f', a 500 I
I i
1 1
I I
I I
I l
l
- 0. 2f ', [1-( h/30 t) 3] for walls I
I I
I, i
I Axial I
Where:
Il 1
l Compression i
i:
1 l
l f', = ultimate compressive I
I I
strength of masonry I
l 1
l l
= 1500 psi i
i i
I' l
I l
t
= wall thickness in inches l
I I
I I
'l i
i h
= clear height in inches I
I I
I
-l I
l l
I I
I 1
l i
Tension i
10 (Table 24-B, UBC-67) l l
1 1
1 1
I I
I I
l Shear with no I
50 l
l l
reinforcement I
(see note 3)
I I
(stirrups) l l
l l
1 i
l l
Shear with rein-i l
I l
forecement (stirrups)I 120 for flexural members l
l l
Stirrups taking
.I 75 for shear walls I
I entire shear l
l 1
1 I
.25f'm = 375 psi on full area 900 l l
l Bearing 1
.3f',
= 450 psi on 1/3 or less}of l
I i
l area $1200 1
I I
I i
j l
Bond (Deformed) i 140 l
i l
i I
>199/3 Rev. O
f00156 ll187-C-8011 TABLE 2 (CONT'D) l I
t l
l Load 1
Materials &
l Allowable Stress: UBC-67 I
I Combination l
Stress I
(psi) 1 I
l Description i
l l
I I
I l
I 1
ID+E l
Reinforcing i
l l
Steel:
I I
I I
I I
i i
l l
Tension &
I 20,000 for rebar #3 thru #7 l
- I l
Compression l
24,000 for rebars larger than #7 l
^ l 1
1 I
I I
I l-l D+E+T l
Stress l
Increase the allowables for I:
o l
I for all i
load combination D + E by a 1:
l l
materials I
factor of 1.3 l-1 i
i 1:
I i
I 1 D + E' l
Masonry:
The allowable masonry stresses for load l~
l I
combination D + E shall be increased as follows:l' l D + W' I
i l
l I
I I
I l
Increase Factor 1.
I D + E'
+T l
Compression i
i o
l l
axial:
1 2.0 l-l D+F l
flexural:
1 2.5 1
1 1
I I
i 1.05D+1.25P l
Bearing:
1 2.5 l
1 1
1 I
i 1.05D+1.0P' l
Shear and Bond:-
l 1.67 l-1 I
I I
I 1.05D+1.0T l
Tension i
1.67 l
a l
l l
1 1
I I
I P-199/3 Rev. 0
___-.,y e
7 v
w'^
TABLE 2 (Cont'd) r l
i
'l Load 1
Materials & Stress i
Allowaole Stress l Combination i
Description l
UBC-67 I
I I
I i
l l
l D& E' l,
Reinforcing l
l Steel:
I D + w' I
I I
I l D+E
'+T l
Tension I
0.9 Fy, provided lap slice lengths o
l l
Compression I
and embedment (anchorage) develop l D+F l
-l this stress level.
Allowable bond I
i I
stresses may be increased by a 1 1.05D+1.25P l
I factor of 1.67 in determining
(
l I
l splice and anchorage lengths.
[
l 1.05D+1.0P' l
l
{
l i
I
{
l 1.05D+1.0T I
I a
I i
1
{
Notes:
1.
The core concrete (or cell grout) has average compressive strength f'c of 3800 psi.
2.
UBC allowable stresses for masonry are based on f'm = 1500 psi (Ref. sec. 2404 UBC-1967) 3.
Web reinforcement shall be provided to carry the entire shear in excess of 20 psi whenever there is required negative reinforcement and for a distance of one-sixteenth the clear span beyond the point of inflection.
e l
P-199/3 Rev. 0 l
- - - - - \\
~
11187-C-8011 bt.2.l.IL5G APPENDIX 0 i
COMMENTARY ON CRITERIA FOR THE RE-EVALUATION OF CONCRETE MASONRY WALLS IN RESPONSE TO NRC I&E BULLETIN 80-11 FOR THE PEACH BOTTOM ATOMIC POWER STATION UNITS 2 AND 3 PHILADELPHIA ELECTRIC COMPANY BECHTEL POWER CORPORATION San Francisco, CA.
9 Tx A
/nle ISSoEo rOR oSE
'P-193/3 m.
w, yy~,
g y
yp-.-
re--y
+ --,,.
g-9.w--------
g t. C, 4. in,>.
a. -
I e
CONTENTS 1.0 GENERAL 2.0 GOVERNING CODE 3.0 LOADS AND LOAD COMBINATIONS 4.0 MATERIALS 5.0 DESIGN ALLOWABLES 6.0 ALTERNATIVE ACCEPTL3CE CRITERIA 7.0 ANALYSIS & DESIGN REFERENCES l
i P-l!s9/3 Rev. 0 m
fCeiiSG COMMENTARY ON CRITERIA FOR THE RE-EVALUATION OF CONCRETE MSONRY WALLS 1.0 GENERAL 1.1 Purpose On May 8,1980, the NRC issued IAE Bulletin 80-11 er. titled,
" Masonry Wall Design", to cert.ain Owners of operating reactor facilities. One of the tasks required by the bulletin was to establish appropriate re-evaluati,on criteria.
A detailed justi-fication of the criteria along with quantified safety margins are also to be provided by the Owner.
This comentary serves as justification of the criteria used and provides a discussion of the margins of safety.
i 1.2 Scope y
s The concrete masonry walls are evaluated for all applicable j
loads and load combinations.
Calculated wall' stresses are first compared against an allowable stress criteria.
In general, wall stresses are maintained within the elastic range of the load carrying components.
If allowable stresses are exceeded, then wall stability is checked using ultimate strength or inelastic
- design approaches and safety systems on or near the wall are evaluated to determine if the displace-ments might adversely affect the intended function of safety related piping and equipment.
4
' Rev. 0
Anchor bolts, embeds and bearing plates provided for support of systems attached to the walls are the subject of another NRC bulletin and are not considered to be within the scope of this evaluation.
2.0 GOVERNING CODE Projects have the option of using the code referenced in the Safety Analysis Report (SAR) applicable to masonry or ACI 531-79.
These l
codes do not address the abnormal loads typically applied to nuclear
}
power plant design.
Therefore, supplemental allowables and alterna-tive design techniques are specified in the criteria for cases not directly covered by the code..
3.0 LOADS AND LOAD COMBINATIONS f
i The loads identified and defined in t,he SAR for safety related struc-i tures form the basis for licensing of the plant and are used in the i
evaluation of the masonry walls.
The load combinations listed in j
the SAR for safety rela,ted concrete structures are used except if licensing commitments related to load combinations are not identified in the SAR or other project documents, then applicable loads with a J
load factor of unity are combined and form the basis for the evalua-tion.
i 4.0 MATERIALS i
I j
.}
Material strengths are largely determined by review of project speci-i 6
fications, drawings and field documentation.
It may also be necessary,
+
i,n some cases, to perform in-situ tests or to test samples taken from i
Rev. 0 3-~w-.
m_
.m
the as-built structure to supplement data obtained from project docu-ments.
5.0 DESIGN ALLOWABLES Allowables in this section apply to loads and combinations of 5.1 loads which are normally encountered during plant operation or shutdown, and include ' dead loads, live loads, normal operating thermal effects, and pipe reactions.
In addition, this section covers allowables for loads infrequently encountered, such The loads in as operating basis earthquake and wind loads.
the various load combinations "have no increase factors and stresses are maintained well within the elastic range.
In general, the governing code allowables are applied.,'However, for cases not covered by the code, such as collar joint shear and tension, and grout tension, allowables are based on a l
factor of safety of 3 against failure.
The strength of mortared or grouted collar joints,3 inches or less in thickness, is highly dependent on the degree of consoli-dation of the mortar or grout, the moisture content of the mix and the block, and the constructio,n workmanship.
Therefore,
)
tension and shear strength, if required, are to be established by tests.
The statistical determination of ultimate strength will be consistent with methods used to verify f'c in ACI-318 and will reflect a probability of less than 1 in 10 that a random individual strength test will be below the ultimate strength.
The 301, stress increase for load combinations containing nonnal operating thermal effects'or displacement limited loads has been typically accepted in the industry for reinforced concrete and Rev. 0 88*
e e
g
,,,,,-,,n
,m.
n e---,,w,m
,-n-,,
~
d'iYih fig.
o m r-r= w n 4-is considered reasonable for masonry.
The factor of safety against failure of the masonry reduces from 3.0 to 2.3, still well within the elastic range.
In-plane strain allowables for interstory drift effects for non-shear walls were established well below the level of strain required to initiate significant cracking.
The allowable strain for a confined wall was' based on the equivalent compres-sion strut model discussed in Reference I and modified by a factor of safety of 3.0 against crushing.
Test data (References 1 through 7) was reviewed to determine cracking strains for confined masonry walls subjected to in-plane displacements and confirms the predicted strain as given by the equivalent strut model.
5.2 This section deals with factored loads and other abnormal loads which are credible but highly improbable such as the safe shut-down earthquake, tornado loads and loads generated by a postu-lated high-energy pipe break accident.
Code allowable stresses for masonry in tension, shear and bond are increased by a factor of 1.67.
In general, this provides a factor of safety against failure of 1.8 (3 + 1.67).
Masonry compression stresses are increased by factors ranging from 2.0 to 2.5 with a minimum safety factor of 1.2 (3 + 2.5).
Reinforcing steel is allowed to approach 0.9 times the yield strength which is typical for reinforcing steel which is re-quired to resist factored and abnormal loads.
. Stresses due to the local effects of abnormal dynamic loads, such as missile impact. jet impingement or pipe whip, may exceed the allowables.
However, safety systems attached or G
Rev. 0
f(,'.8 $ (*
11187-C-8011 adjacent to the wall are evaluated to determine if severe cracking, local spalling, or excessive deflections will result in loss of required function of the system or equipment.
Where gross failure of a masonry wall must be precluded, the provisions of ACI 349-76 Appendix C, or applicable theoretical techniques or experimental evidence is used to evaluate wall acceptability.
5.3 Damping for unreinforced uncracked walls was conservatively set at 2% for OBE and SSE corresponding to stress levels ranging from approximately 0.3,to 0.6 of ultimate.
Damping for reinforced walls which are expected to crack due to out-of-plane seismic inertia are conservatively set at 4%
These values are typically recognized as being realistic for reinforced concrete, yet conservative for reinforced masonry.
~
5.4 The modulus of rupture of concrete, grout and mortar was assumed to vary by 20%, therefore, a lower bound modulus of rupture.is determined by applying a reduction factor of 0.8 to the theoretical concrete modulus of rupture of 7.5/ f'c or to the modulus of rupture determined by testing samples taken from'the as-built structure.
For masonry, the modulus of rupture is approximated by increasing the code allowable flexural tensile stress by the factor of safety of 3 and then applying the 20% redustion to arrive at a lower bound value.
(0.8 X 3 Ft = 2.4 Ft, where Ft is the code allowable tensile stress.) hirn msny, 'the upper bcund nodul.us of rupture may be c w idered as 9/f'c.
e Rev. 0
- 7..
6.0 ALTERNATIVE ACCEPTANCE CRITERIA Masonry walls (a) that are not relied upon to provide strength of l
, the structure as a whole, and (b) that are subjected to out-of-plane seismic inertia loading causing flexural stresses in excess of design allowables may be evaluated by means of the " energy balance technique" for reinforced walls. Reinforced masonry walls evaluated
~
by the " energy balance technique" (Reference 8 and 9) must have sufficient capability to preclude brittle failure and allow rela-tively large ductile flexural deformations.
Tests" (Reference 13) indicate that when flexure is the dominant action, ductilities are in excess of 25.
Other tests (Reference 14) show that even when compression failures occur, ductilities in excess of S can be i
achieved. When reinforced masonry has adequate shear and compres-sion capability, its behavior is expected to parallel that of i
reinforced concrete where allowable ductilities for predominately non-structural elements are conservatively set at 10.
It is reason-able that for out-of-plane seismic loading 'on non-shear walls con-structed of masonry where brittle failures are precluded that a pennissable ductility of 5 is acceptable as long as the safety systems are not jeopardized.
Masonry walls confined within a rigid frame or structure can develop substantial resistance to out-of-plane loadings after flexural crack-ing and may be evaluated by use of the theory of arching (Reference 10 through 12).
Particular attention is given to the rigidity of the wall boundary and to the effect of a gap between the wall and its support.
Operability of safety related equipment and systems as affected by excessive deflections of the masonry walls is of primary importance,
in this alternative criteria. Therefore,duetotheunc(rtainties involved in,' calculating the displacements, a factor of 2 is applied to the calculated deflections and system operability is evaluated
.accordingly.
e Rev. O I
-_ _ ' T :T~'T~~ T **., f *1__ _ __ _ _ _. _ _ _ _.. _
~ ~"
3
' i )5 ' *V; 1118'e-C,u i 7.0 ANALYSIS AND IESIGN 7.1 'Ihe structural response of the mascnry walls subjected to out-of-plane seismic inertia loads is based on a ccnstant value of groes or trera-formed sections (censidering block ard grout ou the ccmpression side and neglecting block and mortar joints on tension side) nment of inertia along the span of the wall for the elastic (uncracked) con-diticn. If the wall is cracked, a better estimate of the nment of inertia is obtained by use of the ACI-318 f-ila for effective acanent of inertia used in calmlating 4 Mate deflections.
(Reference 15)
The effects of higher modes of vibration and variations in fre-quencies are considered on a case-by-cne basis.
The use of the average acceleration of the floors supporting the wall is considered sufficiently accurate for the purpose of this evalu-ation.
7.2 The determination of the out-of-plane structural strength of masonry walls is highly sensitive to the boundary conditions assuned for the analysis.
Fixed end conditions are justified for walls (a) built into thicker walls te continuous across walls and slabs. (b) that have the strength to resist the fixed end moment, and (c) that have sufficient support rigidity to prevent rotation.
Otherwise, the wall edge is simply sup-ported or free depending on the shear carrying capability of the wall and support.
Distribution of concentrated loads are affected by the bear-ing area under the load, horizontal and vertical wall stiff-ness, boundary conditions and proximity of load to wall sup-ports.
Analytical procedures applied to plates based on elastic theory are used to determine the appropriate distribu-j tion of concentrated loads. A conservative estimate of the localized moment per unit length for plates supported on all Rev 0
e I
.....p...
yy
.o
~
- e.,
edges can be taken as:
g = 0.4P where:
Mg = Localized moment per unit length (in-lbs/in)
P = Concentrated load perpendicular to wall (lbs)
For loads close to an unsupported edge, the upper limit moment per unit length can be taken as:
Mg = 1.2P For predominately one-way action, an effective beam width of 6 times the wall thickness for distribution of concentrated loads is conservative for the following conditions:
a)
Concentrated load at midspan; simple supports:
L >9.6T b)
Concentrated load at midspan; fixed supports:
L 719.2T c)
Concentrated load on a cantilever:
h r2.4T d)
Couple at midspan; simple supports:
a >4.8T e)
Couple near a support; simple supports:
a 72.4T where:
L is the beam length h is the distance from the fixed end.t'o the point of load application a
is the distance between the concentrated loads producing a couple T is the thickness of the wall Rev. 0
~n tip
- y.
Interstory drift values are derived from the original dynamic analysis.
Strain allowables depending on the degree of con-finement are applied for in-plane drift effects on non-shear walls and are set at sufficiently conservative levels for in-planc effects alone that a reasonable margin remains for out-of-plane loads.
Out-of-plane drift effects are considered if some degree of fixity exists at the top and/or bottom of the wal l.
s e
4 e
4 e
1 e
(
)
l nev. 0 o
9 s
e hp
( if 'i 5G REFERENCES 1.
Klingner, R. E. and Bertero, V. V., "Infilled Frames in Earthquake Resistant Construction," Report No. EERC 76-32. Earthquake Engineer-ing Research Centar. University of California, Berkeley, CA December, 1976.
2.
Heli R and Salgado, G., "Comportamiento de muros de mamposteria su-jetos a cargas laterales " (Behavior of Masonry Wall Under Lateral Loads._ Second Report.)
Instituto de Ingenieria, UNAM, Informe No.
237, September,1969.
, Meli, R., Zeevart W. and Esteva, L "Comportamiento de muros de 3.
mamposteria hueca ante cargas alternades," (Behavior of Reinforced Masonry Under Alternating Loads), Instituto de Ingenieria, UNAM, Infome No.156, July.1968.
4.
Chen, S. J., Hidalgo P. A., Mayes, R. L., Clough, R. W., McNiven, H. D.,
" Cyclic Loading Tests of Masonry Single Piers, Volume 2 - Height to Width Ratio of 1 " Report No. EERC 78-28, Earthquake Engineering Re-Search Center, University of California, Berkeley, CA, November,1978.
5.
Mainstone R. J., "On The Stiffnesses and Strengths of Infilled Frames,"
Proc. I.C.E., 1971.
6.
Hidalgo, P. A., Mayes, R. L., McNiven. H.D., Clough, R. W., " Cyclic Loading Tests of Masonry Single Piers, Volune 1 - Height to Width Ratio of 2 "
Report No. EERC 78/27. Earthquake Enginecting Research,
Center, University of California, Berkeley, CA,1978.
7.
Hidalgo, P. A., Mayes, R. L., McNiven. H. D., Clough, R. W., " Cyclic Loading Tests of Masonry Single Piers, Volune 3 - Height to Width Ratio of 0.5," Report No. EERC 79/12. Earthquake Engineering Research Center, University of California, Berkeley, CA,1979.
Rev. O J
~ i j.-
~
11187-C-8011
( ;7, g.;
/ (7'
~q t
8.
Bl une, J.
A., N. M. Nemark,* and L. H. Corning, " Design of' Nultistory Reinforced Concrete Buildings for Earthquake Motions," Portland Cement Association, IL.
1961.
t 9.
Newart, N. M., " Current Trends in the Seismic Analysis and Design of High-Rise Structures " Chapter 16. Earthquake Engineering, Edited by R. L. Wiegel, McGraw-Hill, 1970.
10.
Gabrielson, B. L. and K. Kaplan', " Arching in Masonry Walls Subjected to Out-of-Plane Forces," Earthquake Resistance of Masonry Construc-tion. National Workshop, NBS 106,1976., pp. 283-313.
i 11.
McDowell, E. L., K. E. McKee, and E. Savin, " Arching Action Theory of Masonry Walls," Journal of the Structural Division, ASCE Vol. 82, No. ST2, March,1956, Paper No. 915.
12.
McKee, K. E. and E. Savin, " Design of Masonry Walls for Blast Load-ing " Journal. of the Structural Division. ASCE Transactions, Proceed-ing Paper 1511, January 1958.
13.
Scrivener, J. C., " Reinforced Masonry-Seismic Behaviour and Design,"
Bulletin of New Zealand Society for Earthquake Engineering, Vol. 5, No. 4. December 1972.
i 14.
Scrivener, J. C., " Face Load Tests on Reinforced Hollow-brick Non-1 loadbearing Walls," New Zealand Engineering, July 15, 1969.-
15.
Branson, D. E., " Instantaneous and Time-Dependent Deflections on Simple and Continuous Reinforced Concrete Beams," HPR Report No. 7 Part i, A1abama Nighway Department, Bureau of Pub 1ic Roads, August 1965,, pp. 1-78.
e i
5@@S -