^Bureau of Standards
The program of research on building materials and structures, carried on by the

National Bureau of Standards, was undertaken with the assistance of the Central Housing Committee, an informal organization of governmental agencies concerned with

housing construction and finance, which is cooperating in the investigations through a subcommittee of principal technical assistants.

CENTRAL HOUSING COMMITTEE

SUBCOMMITTEE ON TECHNICAL RESEARCH

Walter Junge, Chairman. Arthur C. Shire, Vice Chairman.

Federal Housing Administration. United States Housing Authority.

Sterling R. March, Secretary

Albert G. Bear,

Veterans' Administration.

Pierre Blouke,

Federal Home Loan Bank Board (Federal Loan Agency).

Carroll W. Chamberlain,

Procurement Division (Treasury).

Joseph M. DallaValle,

PubHc Health Service (Federal Security

Agency).

John Donovan,

Farm Security Administration (Agriculture).

George E. Knox,

Yards and Docks (Navy).

Vincent B. Phelan,

National Bureau of Standards (Commerce).

Edward A. Poynton,

Office of Indian Affairs (Interior).

George W. Trater,

Forest Service (Agriculture).

Elsmere J. Walters,

Construction Division (War).

CHAIRMEN OF SECTIONS

Specifications Materials Maintenance

Carroll W. Chamberlain Elsmere J. Walters John H. Schaefer

Mechanical Equipment Methods and Practices

Robert K. Thulman

NATIONAL BUREAU OF STANDARDS

STAFF COMMITTEE ON ADMINISTRATION AND COORDINATION

Hugh L. Dryden, Chairman.

Mechanics and Sound.

Phaon H. Bates, Gustav E. F. Lundell,

Clay and Silicate Products. Chemistry.

Hobart C. Dickinson, Addams S. McAllister,

Heat and Power. Codes and Specifications.

Warren E. Emley, Henry S. Rawdon,

Organic and Fibrous Materials. Metallurgy.

The Forest Products Laboratory of the United States Department of Agriculture

is cooperating with both committees on investigations of wood constructions.

[For list of BMS publications and how to purchase, see cover page III.]
UNITED STATES D E 1' A R T ]S f i: N 'J" () E (

' ( ) M M i; K (' IC • I larty I ,. Moi)kins, Secretary

NAT I ON AJ, H U R A I! OE STANDARDS • l.yman J. Hriggs, director

BUILDING MATERIALS

and STRUCTURES

REPORT BMS2S

Structural Properties of Conventional Wood-Frame Constructions

for Walls, Partitions, Floors, and Roofs

hy GEORGE E. HECK

ISSUED SEPTEMBER 13, 1939

The National Bureau of Standards is a fact-finding organization;

it does not "approve" any particular material or method ot construction. The technical findings in this series of reports are to be construed accordingly.

UNITED STATES GOVERNMENT PRINTING OFFleE • WASHINGTON • 1939

FOR SALE BY THE SUPERINTENDENT OF DOCUMENTS, WASHINGTON, D. C. • PRICE I5 CENTS
Foreword

Tliis report is one of a series issued by the National Bureau of Standards on the

structural properties of constructions intended for low-cost houses and apartments. It deals with the determination of the properties of wood-frame construction. It differs from most of the other reports in the series in that no industrial or commercial concern sponsored the tests; instead the constructions were built and tested at the Forest Products Laboratory. The results afford a basis for comparing other and newer materials

and types of construction.

This report embraces load-deformation relations and strength properties of woodframe wall, partition, floor, and roof constructions. The constructions were subjected

to compressive, transverse, concentrated, impact, and racking loads by standardized

methods substantially as described in Report BMS2, Methods of Determining the

Structural Properties of Low-Cost House Constructions.

Lyman J. Briggs, Director.

["]
Structural Properties of Conventional Wood-Frame Constructions,

for Walls, Partitions, Floors, and Roofs

CON T E N T S

Page

Foreword - ii

I. Introduction 1 II. Sponsor 2

III. Specimens and tests 2

1. Specimens 2

2. Plastering 3

3. Test procedure 3 IV. Materials 3

1. Wood 3

(a) Framing 3

(b) Sheathing 3

(c) Laths 3

(d) Siding 3

(e) Shingles 3

2. Paper 3

3. Plaster 3

(a) Mix 3

(b) Tensile strength of briquets- - 4

4. Nails 4

V. Wall frames QAj 4

1. Comments 4

2. Description 4

3. Compressive load 4

4. Transverse load 6 VI. Walig^ 6

1. Description 6

2. Compressive load 8

3. Transverse load 8

4. Concentrated load 9

5. Impact load 11

6. Racking load 11

VII. Partition QD—load-bearing 15

1. Comments 15

2. Description 15

3. Compressive load 15

4. Transverse load 16

5. Concentrated load 16

6. Impact load 16

7. Racking load 17

VIII. Floor QB 17

1. Description 17

2. Transverse load 18

3. Concentrated load 18

4. Impact load 18 IX. RoofQC 18

1. Description 18

2. Transverse load 19

3. Concentrated load 19 X. Loads and deflections in transverse tests. 20 XL Significance of set readings 20

XII. Weights 21 XIII. Two methods of testing walls under compressive load 21

1. Comments 21

2. Description 22

3. Test results 22

4. Discussion 22 XIV. Selected references 23

ABSTRACT

For the program on the determination of the structural properties of low-cost house constructions, the

Forest Products Laboratory built 39 specimens repre- senting conventional wood-frame constructions for

walls, partitions, floors, and roofs. In addition, six wall frames without covering were built. The wall-frame specimens were subjected to compressive and transverse loads; the wall and partition

specimens to compressive, transverse, concentrated,

impact, and racking loads; the floor specimens to

transverse, concentrated, and impact loads; and the

roof specimens to transverse and concentrated loads. The transverse, concentrated, and impact loads were

applied to both faces of wall specimens. For each of these loads three like specimens were tested. The

'Engineer, Forest Products Laboratory, Forest Service, U. S. De

deformation under load and the set after the load was removed were measured, except for concentrated loads,

for which the set only was determined. The results are presented in graphs and in tables.

I. INTRODUCTION

Information on wood-frame construction and

on masonry construction, both of which have

been widely used and whose behavior in service

is generally known, is desirable as a basis for

judging the merits of the newer constructions

included in the series of tests on the structiu-al properties of low-cost house construction.

nent of Agriculture.

[1]
Such information on masonry appears in report

BMS5, Structural Properties of Six Masonry

Wall Constructions. The present report deals

with one type of wood-frame construction for each of the elements; walls, partitions, floors,

and roofs, specimens of which were built and

tested at the Forest Products Laboratory of the

U. S. Department of Agriculture. The Laboratory ahd the University of Wisconsin, both in

Madison, Wis., cooperate on problems related

to wood and wood products.

In frame-house construction various species

and grades of lumber are used for framing, wall

and roof sheathing, and subflooring, with considerable diversity in the sizes, spacing, and

arrangement of elements. Materials other than

wood are used for wall sheathing and subflooring

as well as for inside and outside finish faces, and

a variety of materials serves as plaster base when

plaster is used. Thus it is obviously impossible

to select any one combination as the typical

conventional wood-frame construction.

The principal features of the constructions,

tests of which are reported herein, are: Walls.—Studs (2 by 4 in. nominal) spaced

16 in. on centers and covered outside with

bevel siding on diagonally placed sheathing

boards and inside with gypsum plaster on wood laths. Partitions. —Studs (2 by 4 in. nominal)

spaced 16 in. on centers and covered on both

sides with gypsum plaster on wood laths.

Floors.—Joists (2 by 8 in. nominal) spaced

16 in. on centers, cross-bridged at midspan,

covered above with hardwood strip flooring over diagonally placed boards as subflooring,

and below with gypsum plaster on wood laths. Roof.—Rafters (2 by 6 in. nominal) spaced

24 in. on centers and covered above with wood

shingles on sheathing boards laid perpendicular

to the rafters. All specimens tested were completed parts

of walls, partitions, floors, and roofs except for the omission of paint, wallpaper, or other

surfacing.

The estimated prices of these constructions

in Washington, D. C, as of July 1937 are: Wall $0. 43/ft2 Partition . 31/ft2 Floor . 49/ft2 Roof . 27/ft2

In some other wood constructions tested by the

| National Bureau of Standards the framing was j very similar, but the covering materials differed. 1 In addition to tests on specimens of the con- ! structions outlined, tests were made on wall i frames without any inner or outer covering.

The constructions were subjected to compressive, transverse, concentrated,impact,and racking

loads, thus simulating loads to which the elements L

of a house are subjected in actual service. H

The deflection under each increment of load H

and the set after its removal were determined, H

except for concentrated loads for which set H

only was measured. Maximum loads were 1

also determined except in the impact-load test. I

II. SPONSOR I

No industrial or commercial concern partici- i pated in these tests as sponsor. The specimens

| were built by experienced workmen at the

Forest Products Laboratory.

III. SPECIMENS AND TESTS \

1. Specimens

Table 1 shows the construction symbols and

specimen designations, the sizes of specimens,

and manner of application of the loads.

Table 1. —Test specimens

Element

Construction- svmbol

Specimen

designation Kind of test Size Load applied

/' Wall QA CI, C2, C?.. Compressive.

-

4X 8 Upper end. Do QA Tl, T2, T3- Transverse. 4X 8 Inside face. Do..., QA Tl,, T5, T6 do 4X 8 Outside face. Do.... QA P1,P2,PS<' Concentrated Inside face. Do... QA Pit, P5, PS " do 4X 8 Outside face. Do... QA 11,12.13.... Impact 4X 8 Inside face. Do... QA IA, If), 16.... do 4X 8 Outside face. Do.. QA R1.R2, R3. Racking 8X 8 End of top

plate. Wall QA} CI . C2, CS. . Compressive.

-

4X 8 Upper end. frame b Do... QAf Tl, T2, T3. Transverse 4X 8 Either face. Partition = QD CI, C2. CS. Compressive. - 4X 8 Upper end.

(load- bearing) Do... QD Tl. T2, T3. Transverse... 4X 8 Either face. Do.... QD P1,P2,P3^ Concentrated. Do. Do ... QD 11,12,13... Impact 4X 8 Do.

Do.... QD R1. R2, R3. Racking 8X 8 End of top

plate. Floor QB Tl, T2, T3. Transverse. _ _ 4X121/^ Upper face. Do._._ QB P1,P2,P3» Concentrated. Do.

Do.... QB 11,12,13.... Impact '4X12M Do.

Roof OC Tl, T2, T3. Transverse. _

.

4X14'/^ Do. Do... OC P1,P2,P3' Concentrated. 4X14H Do.

a These specimens wereundamaged portions of the specimens used for the transverse tests.

t The vi^all frames were tested to get a comparison between the bare frames and the specimens representing complete walls and partitions.

» Tests were not made on nonload-bearing partitions, because they are

identical with load-bearing partitions.
Specific-gravity determinations {see tables

2 to 6) and photographic records of defects in

the framing and sheathing indicate the quality

of material in the different specimens. The

character of the material in the various speci- mens is illustrated by several photographic

figures in this report.

2. Plastering

The specimens were set up for plastering in

the positions they would occupy in service. The

plaster was applied by an experienced plasterer

and struck to grounds projecting % in. from the

face of the frame. The laths were thoroughly

sprinkled with water before the plaster was

applied and the first coat was also sprinkled

before application of the second coat. At least

1 day was allowed between the first and second

plaster coats.

3. Test Procedure

The specimens were tested in accordance

with BMS2, Methods of Determining the

Structural Properties of Low-Cost House Constructions, except for the compressive-load test in which a pin-end condition at the bottom

rather than a flat-end condition was used. The

walls and partitions are close to the dividing

line between Euler columns and columns of

intermediate length, and it was believed that

in such instances a flat bearing at one end might

result in an indeterminate increase in load above

that corresponding to pin- or hinged-end conditions. In actual structures, vertical loads

ordinarily cause compression at right angles

to grain in horizontal parts at the top and bottom of the walls. Because the modulus of

elasticity in compression at right angles to grain is low, there is no certainty of a significant

fixity efi^ect. A further consideration is that,

because of the plasticity of wood under stress

in compression perpendicular to grain and be- cause of shrinkage and swelling with changes in moisture content, such fixity as may exist at time of erection may gradually decrease. It was therefore thought best to load the speci- mens through knife-edges at both ends in order

to make certain that in test there would be no

fixity.

Compressive-load tests were made later at the National Bureau of Standards to determine

the difference in tlie results obtained on pin-end

and flat-end bearings at the bottom. The re- sults of these tests are given in section XIII.

The tests v/ere begun F'ebruary 15, 1938, and

completed March 16, 1938. All plastered

specimens were tested 28 days after the final coat of plaster was applied.

IV. MATERIALS

1. Wood

(a) Framing

All framing, i. e., studs, joists, plates, headers,

and rafters, was No. 1 Douglas fir dimension.

The average moisture content of this material was about 15 percent.

(6) Sheathing

Nominal 8-in. shiplap was used for the wall

sections and 8-in. boards for the subfloor and

roof. This sheathing lumber was No. 2 com- mon southern yellow pine. When received

it averaged about 25-percent moisture content.

It was piled and stickered in a warm room and was at about 10-percent moisture content when

the specimens were buUt.

(c) Laths

The laths were %- by 1 Yo-iu. white pine wood

laths 4 ft long.

((/) Siding

The siding was 6-in. bevel (actual width 5K

in.) western red cedar.

(e) Shingles

The shingles were 16-in. (five butts to 2 in.)

edge-grain western red cedar.

2. Paper

The buUdmg paper applied over the wall

sheathing, between the subfloor and the finish

floor, and between the roof boards and the

shingles was asphalt-impregnated and surfacetreated sheathing paper weighing 50 pounds

per roll of 500 ft 2.

3. Plaster

(a) Mix

The plaster on wall, partition, and floor specimens consisted of two coats mixed accord-

[3]
iiig to the manufacturer's recommendations in the proportions of 1 part of prepared gypsum

plaster (U. S. Gypsum Co.) to 2 parts of plaster

sand, by weight, for the first coat and 1 part of

plaster to 3 parts of sand, by weight, for the

second coat, with the necessary water to form a workable mixture.

(6) Tensile Strength of Briquets

Standard briquets were taken from each day's

mixing of first and second coats to give an indication of plaster strength. These, as well as the specimens which they represented, were

tested on the 28th day after completion of the

plastering. The average tensile strength of the

briquets was 175 and 1 15 Ib/in.^ for the first and

second coats, respectively.

4. Nails

The nails used in building the various speci- mens were the normal quality of wire nails

usually obtained on the market. The size and

number used in the different specimens are given under the description of each specimen.

V. WALL FRAMES QAf

1. Comments

The tests on wall frames without covering were included to obtain data that by comparison

with data on wall and partition specimens would

indicate the effect of sheathing, siding, and

plaster on the structural properties of these

constructions.

2. Description

The wall frames for compressive- and trans- verse-load tests were 4 ft wide by 8 ft high overall. They consisted of three studs spaced 16 in. on centers, with a stud at midwidth, a single

floor plate, and a double top plate all of nominal

2- by 4-iu. material, actual dimensions l%s by

3?(6 in. The floor plate and the lower imit of

the top plate were nailed with two 16d connnon

wire nails driven through these parts into the

ends of each stud. The upper unit of the top

plate was fastened to the lower with three

lOd common wire nails per stud space. Three frames were tested under compressive

and three imder transverse load. Each frame

for compressive load was braced to prevent

bending of the studs in the plane of the frame.

The braces consisted of five nominal 1- by 4-in. i pieces, two at right angles to the studs at the onethird points of the frame height and three (one

in each space) placed diagonally at about 45°

to the studs (fig. 1).

3. Compressive Load

In compressive-load tests a small initial load was applied to hold the apparatus in place.

Readings of shortening and deflection were

taken under this initial load. Additional load was then applied until it reached a predetermined value and shortenings and lateral deflection were read after which the load was

reduced to the initial value and readings of set made. This was repeated several times, in- creasing the load each time to a greater value

than in the preceding application, and finally

the load was increased continuously until fail- ure occurred. The several values to which the

load was increased before testing to failure are indicated by the graphs of test results. During

the periods of load application, the movable

head of the testing machine was operated at a speed of 0.064 in./min.

Wall frame QAf-C3 after test is shown in

figure 1. The results for specimens QAf-Cl, C2, and

C3 are given in table 2 and in figures 2 and 3.

Table 2.

Structural properties of wall frame QAf

[Average moisture content of the frames at time of test was 9.5 percent and

the specific gravity (based on weight and volume oven dry) was 0.46]

Load Load

applied

Speci- men

desig- nation

Maxi- mum

load Remarks

Compressive^^.

[Eccentric

I to top

[ plate.

CI

C2

Kipslfl"- 3.30

4. 28

3. 46

Failure by crushing at top plate by studs fol- lowed by rocking over

of top plate. Do. Do.

Average . 3.68

Transverse One face..

1 Tl

i T2

T3

mm

213

159

175

Failure by tension

through small knots in one stud. Failure by tension in center stud. Failure by tension in one

outside stud.

Average, 182

» A kipisl.UOOlb.

[4]
Failure occurred by crushing of the top plate

at the studs accompanied by rocking over of this plate toward the eccentric-load side and pulling

of the nails fastening the plate to the studs near

the opposite edge.

Before testing these specimens in compression, the modulus of elasticity was determined

for each one by making a load-deflection test within the proportional limit. The load was

applied and the deflection measured as in the

transverse-load test, except that no intermediate

set readings were taken.

The average modulus of elasticity was 1,587,-

000 lb/in. 2 (individual values were 1,670,000,

1,420,000, and 1,670,000 Ib/in^). Computations from this value show that had the wall

frames acted as Euler columns, the average

maximum load in the compressive-load test would have been approximately 34,200 lb,

whereas the actual average was 14,710 lb.
4. Transverse Load

In the transverse test load was applied until

it reached a predetermined value; the deflec- tion was read; the load was removed; and the

4

5;

o

3

2

0

• o

•••

1 —1—

o

1 - 1 . •••

1 —UCO o

1

1 •••

; •«•

/

cno

cyo

/ >^

Q4f

0 0.05 0.10 0.15 shorfenin(^ in.

Figure 2.

Compressive load on wall fra^nes QAf.

Load-shortening (open circles) and load-set (solid circles) results

for specimens QAj-Cl, C2, and C3. Load applied to top end at onethird thickness of the frame from its face; to bottom end at center line

of thickness. The loads are in kips per foot of width of specimen (length

of floor and top plates 4 ft 0 in.).

set was then read. Tliis was repeated several

times, increasing the load each time to a greater

value than in the preceding application, and

finally the load was increased continuously

until failure occurred. The several values to which the load was increased before testing to

failure are indicated by the graphs of test

results. During the periods of load application the

movable head of the testing machine was operated at a rate of 0.135 in./min.

The results for specimens QAf-Tl, T2, and

T3 are given in table 2 and in figure 4. Failures were by tension in the studs.

—

5Pro

2

0

• <

» a

m cr

1 i

1 /

/o

1 /

1 / •CD

IJL IT

T

0.2 0 0.2 0.4

laferal deflecfion in.

VI. WALL QA

1. Description

Wall specimens for the compressive, transverse, and impact tests were 8 ft high by 4 ft wide, and those for the racking test were 8 ft

| high by 8 ft face width. The studs and

plates were nominal 2 by 4's (actually 1%6

by 3/16 in.) spaced 16 in. on centers with a

stud at midwidth of both the 4-ft and the

8-ft specimens. The floor plate and the lower

unit of the double top plate were nailed with

two 16d common wire nails driven through the

plates into the ends of each stud. The upper

unit of the double top plate was fastened to the lower with three lOd common wire nails

per stud space. Before lathing and plastering the specimens,

the floor plate of each 8-ft specimen was

P'iGURE Z.— Vomprusxive. load on wall frames QAf.

Load-lateral deflection (open circles) and load-lateral set (solid circles) for specimens CI, Ct, and C3. Load applied to top end at one-third thickness of the frame from its face; to bottom end at center of thickness. The loads are in kips per foot of width of specimen (length of

floor and top plates 4 ft 0 in.).

securely nailed to a 6- by 6-in. timber about

10 ft long to facilitate handling and to prevent

lateral deflection of the floor plate during test.

[6
Table 3.

Structural properties of wall QA

IWeiKlils ofninsfnictinnsand of plaster arc shown in table 7. The averaRC moisture content of the frarninp; at time of lest wms 11.1 jierceiit and the

specific gravity (based on weight and volume when oven dry) was (I..''id]

liOad I.oail u|jplii'(l

Compressive fEcccntric to top

\ plate."

AverageTransverse.

Do.

finside (plastered)

\ face.

Averagef Outside (sheathed

1. and sided) face.

Specimen

designation

CS.

Concentrated...

Do.

Average.

flnside

1 face. (plastered)

Average-

/Outside (sheathed

\. and sided) face.

T6.

\P1.

IPS.

P.4- \PB.

i\P6. Averagers?

Impact

Do.

finside (plastered) \ face.

AverageRacking

/Outside (sheathed J Js.

1 and sided) face. ;|

AverageEnd of top plateAverage

Rl.

R2.

Maximum

height of drop a

9.0

' 10.0

10.0

Indentation at

1111) lb Maximum

load

0. 000

.000

.000

0. 000

0. 001 .001 .000

0.001

' 10.0

' 10.0

' 10.0

10.0

Kipslft ^

S. .'i5

7.79

.80

Iblft '262

267

2S9

273

219

215

243

226

318

245

355

1, .'i20 1,300

2,060

1, 623

Kipslft b

2. 03

2. 15

2. 10

Itcniarks

Slij;hl, crushing of plaster at 2.75 kips/ft. First tension

pUisliT crack at s.l."> kips/ft. Final failure due to crushing

of plates at slud ends followed by bending failure in two

sl iids. IlriiilinK of panel was toward the inside face. Plaster crusliid at 2.s,'i kijis/ft. First tension crack in plaster at 7,(i:i kips/ft . l''iiial failure by crushing at upper

plati- followed by (To.ss-liri akiiig of studs at 5.67 kip,s/ft after iiia\iiiiuiii load. I'aiicl dcllcclcd toward insidefacc.

First laihoc in plasti r was cnishiiit;, near top at 4.75 kips/ft. Finid failur<> due to crushing of upper plate followed by

cnKs-brcaking of two studs. Heverse bend^bending

toward outside face at top but toward inside face at center and bottom.

Tension in studs. First plaster crack at load points near maximum load. Tension in studs. Plaster cracks under load points near maximum load. Tension in one stud. Plaster cracks at load points visible only on removal of load after maximum load.

First plaster crack at 63 lb/ft 2 at seventh loading. Princi- pal failure by tension in studs.

First plaster crack under load point at 42 lb/ft ' at fifth loading. Tension at knot in outside stud followed by

horizontal shear in center stud.

First plaster crack across center at 26 lb;ft at fifth loading. Tension at knots in studs.

Loaded at about 1 in. from sheathing joint. Loaded at about 1?4 in. from sheathing joint.

First plaster crack at 2Vo-ft drop. Lath and plaster broke through near center at 9-ft drop. Outside face undamaged.

First plaster crack at 5-ft drop. Plaster badly shattered at

10-ft drop, but no failure in lath aad studs. Outside face undamaged,

Do.

First plaster crack at i;,-2-ft drop. Most of plaster loose at

10-ft drop. Upper face and studs undamaged.

First plaster crack at 2'A-(t drop. Plaster and some lath

loose and failure of one outside stud at small knot at 10-ft drop.

First plaster crack at 2K'-ft drop. Plaster and some lath

loose and slight tension in one stud at small knot at 10-ft drop.

First plaster crack at 1.50 kips/ft. Final failure due to plaster shearing keys and sheathing shearing from floor plate with cross-breaking and splitting of studs.

First plaster crack at 0.88 kip/ft at last loading. Final

failure similar to Rl.

First plaster crack at 0 .50 kip/ft at last loading. Final

failure similar to Rl

.

n Test discontinued at 10-ft drop,

b A kip is 1,000 lb.

0 Specimens loaded on top plate through knife-edge at one-third width of frame from inside face of frame and supported at bottom on similar knife- edge at center of frame.

153037°—39 2 [7]
The sheathing on all walls was applied diagonally at an angle of about 45° with the studs

and nailed with two 8d common wire nails at crossing of studs, floor plate, and upper unit

of the double top plate and with one 8d nail at each crossing of the lower unit of the top plate,

then covered with sheathing paper and finally

bevel siding. The 4-ft specimens had no joints

in the sheathing boards. The 8-ft specimens

defiedion in.

Figure 4.—Transverse load on. wall frames QAf.

Load-deflection (open circles) and load-set (solid circles) results for specimens Tl, T'£, and T3 on the span of 7 ft 6 in. The loads are in pounds per square foot on the area of 30 sq ft (span times the length

of wall represented by the 4-ft specimen).

had joints in sheathing boards located at stud

crossings, as indicated in figure 5. Twenty-one widths of bevel siding were

applied to each specimen with a resulting aver- age exposure of 4 Yn^ in. , the top piece being ripped

to this dimension. The actual widths of the

siding being 5^ in., the average "overlap" was

in., and one 7d siding naU was driven through

the overlapping edges at each stud crossing.

The inner faces of outside walls were lathed

and given two coats of gypsum plaster to a combined thickness of lath and plaster of % in. The laths were nailed with one 3d sterilized.

blued lath nail at each stud crossing. The

laths were applied in courses of eight laths each,

the joints being broken in a imiform manner for each size of specimen, 51 widths of lath being

required in each instance. Support for the

8-in. overhang of the lath at each edge of the

4-ft specimens was provided in conjunction

with the plastering grounds, the supporting

pieces being removed before test (fig. 6).

2. Compressive Load

The operation of the testing machine was as described for wall frames under section V-3.

The results for wall specimens QA-Cl , C2,

and C3 are shown in table 3 and in figures 7 and 8. The average maximum load of 8.38 kips/ft is approximately 60 percent of the value computed by inserting in the Euler column formula

the average value of stiffness {EI) derived

from the transverse-load tests on specimens

QA-Tl, T2, and T3.

The failures were characterized by crushing

of the plaster near the plates, crusliing of the

plates at the ends of the studs, tension plaster

cracks after maximum load, and finally cross- breaking of the studs. In specimens CI and

C2 bending was toward the inside face (negative deflection) despite the fact that the load was eccentric toward that face. The residtant

greater crushing of the upper plates at the edge

toward the sheathed outer face is illustrated

by figure 9. Specimen 03 took a reverse bend,

the deflection being toward the outside face in

the upper half, but toward the inside face at and below the center of the height.

3. Transverse Load

The operation of the testing machine was as described for wall frames under section V-4.

A specimen {QA-Tl) under transverse-load

test is shown in figure 10. The results of the

tests are shown in table 3 and in figures 1 1 and

12, respecti\ ely, for specimens QA-Tl, T2, and

T3 loaded on the inside face, and for specimens

QA-T4, T5, and T6 loaded on the outside face. With the load applied to the outside face,

the first failure was by cracking of the plaster.

When the load was applied to the inside (plas-

[8]
Figure 5.

Wall specimen QA before apjdicalion of laths, plaster, or siding, showing

constrndion of 8- by 8- ft. specimens and

position of joints in sheathing {indicated

by x's).

In racking tests the horizontal forcos were applied in the direction to cause tension in the sheathing, i. c., pushing toward the right at the top of the specimen and

toward the left at the bottom.

tered) face, cracks were not observed until near the maximum load and were usually not

visible until the load was removed.

4. Concentrated Load

A specimen (QA-PS) set up for the concentrated-load test is shown in figure 13. The

micrometer dial and supporting bar sho^vn in

this figure are removed when maldng the

indentation. The circular supporting ring

remains in place.

The results are given in table 3 for wall

specimens QA-Pl, P2, and PS loaded on the

inside face, and in table 3 and figure 14 for wall

specimens QA-P4, P5, and P6 loaded on the

outside face. Indentation on the plastered

face was negligible up to the point where the

plaster crushed or cracked, consequently only

the indentation at 100 lb was recorded for specimens QA-Pl, P2, and PS.

Wlien loaded on the inside (plastered) face,

failure occurred by crushing and cracking of the

plaster and breaking of the laths. When loaded on the outside face, failure occurred by crushing

of the siding under the tool, and splitting and

cross-breaking of the sheathing.

[9]
Figure 6.

Partition specinie7i QD-Tl with laths on

one face only.

The pieces shown at vertical edges formed supports for lath ends and

grounds for plastering and were removed before the specimen w-as tested.

[

1.0

0 0.04 0.08

shortening in.

Figure 7.

Cojnpressive load on wall QA.

Load-shortening (open circles) and load-set (solid circles) results for specimens QA-Cl, C2, and C3. The loads are in kips per foot of width

of speoimen (4 ft 0 in).

1.0

-0.08 -0.06 -0.04 -O.OF 0

laferal defiedion in. Figure 8.

Compressive load <in wall QA.

Load-lateral deflection (open circles) and load-lateral set (solid circles) results for specimens QA-Cl, C2, and CSi. The loads are in kips per foot

of width of specimen (4 ft 0 in).

lOJ
Figure 9.

Crushing of lower face of upper plate against ends of studs in compressive-load test of specimen QA-C2.

5. Impact Load

The results of the impact-load tests are given in table 3 and in figures 15 and 16, re- spectively, for specimens QA-Il, 12, and 13

loaded on the inside face, and for specimens

QA-IJf, 15, and 16 loaded on the outside

face. No failure occurred in the frame members of the wall panels up to the final drop from a

height of 10 ft. In tests with the outside face

up, most of the plaster and some of the laths had

broken loose at this drop. Specimens tested

with the inside (plastered) face up sustained

only a general loosening of the plaster, and in one specimen {II) the laths broke through near

the center at the 9-ft drop.

6. Racking Load

In the racking-load test, load was applied

until it reached a predetermined value; the

deflection was read; load was removed; and

readings of set at zero load taken. This was

repeated several times and finally the load was

increased continuously until failure of the spec- imen occurred. The several values to which

the load was increased before testing to failure are indicated by the graph of test results (fig. 17). During the periods of load application,

the upper end of the specimen was moved longitudinally at a rate of 0.2 in./min.

The walls were tested with the diagonal

sheathing stressed in tension (fig. 5), wliich pre- vious tests have indicated is the weaker dii'ection.

Figure 10. — Wall specimen QA-Tl in position for iransvcrsc-load test.

I 11 I
I

^1

30

40

11

opo

1

••

1

1

• CD • s5

5^^ 59

CT) I

80

40

4-4 0 04 0.8

defiedion in. Figure 11.—Transverse load on tvall QA, load applied

to inside face.

Load-deflection (open circles) and load-set (solid circles) results for specimens QA-Tl, T2, and 73 and on the span of 7 ft 6 in. Loads are

in pounds per square foot of tiie area (span times the width of specimen

30 sq ft).

0.4 08

defiedion

i.2

in. FiGTiRE 12.—Transverse load, on wallQA, load applied to outside face.

Load-deflection (open circles) and load-set (solid circles) results for specimens OA-Ti, T5, and T6 on the span of 7 ft 6 in. Loads are in pounds per square foot of the area (span times the width of specimen

30 sq ft).

Figure J.'i. WUll specimen QA-P3 in /i,.siti<iit for the concentrated-load test.

\ 12 1
800

600

iOO

s;

\200

7

^ ^5^4 ^.^.^ indeniaiion in,

Figure 14.

Concentrated load on wall QA, load applied

to outside face.

Load-indentation results for specimens QA-Pi, P5, and P6.

I 2

defiedion in, Figure 16.

Impact load on wall QA, load applied to outside face. Height of drop-defiection (open circles) and height of drop set (solid

circles) results for specimens QA-IJ,, 15, and 16 on the span of 7 ft 6 in.
0.8

en

-10.6

in OA

I

0.2

0

4-

• c ) y o

/

-1—

1

m • c ) A)0

/ /

1 u

• 0 o

1 — c ) c/

0

0 0.0/ 0.04

shorfehin^ in.

Figure 19.

Co7npressivc load on parlilion QD.

Load-shortening (open circles) and load-set (solid circles) results for specimens QD-Cl, CS, and C3. Loads are in kips per foot of width of specimen (4 ft 0 in.).

f.O ^ 0.8

0.4

0.2

Figure 18.

Parlilion specimen QD~C3 under compres'

sive-load test.

Shortening is read hy moans of the dial gage mounted ou a telescoping rod attached to the liearing plates by pins centered at the middle of the

thickness of the frame and in the planes of the ends of the specimen.

Lateral deflection is the reading of the steel scale whicli is attached to the specimen at midheight against a fine wire stretched between end fit- tings of the telescoping rod and kept taut by rubber bands.

• 1 .o o

• 1 1 o

'i

oi o

) / o

0.01 0.02 0.05

laferal defiedion in.

Figure 20.

Compressive load on partition QD.

Load-lateral deflection (open circles) and load-lateral set (solid circles) results for specimens QD-Cl, C2, and C3. Loads are in kips per foot of width of specimen (4 ft 0 in.).

14
Table 4.

Structural properties of pariiiion QI)

\Veiglits of constructions and of plaster are shown in table 7. The average moisture content of the framing at time of test was 11.3 percent and the

specific gravity (based on weight and volume when oven dry) was 0..5!]

Load Load applied Specimen

designation

Maximum

drop

Indenta100 lb Maximum

load

1 Eccentric to top

\ plate.''

AverageICl

ft in. Kips'JI «

6. 58

0.44

7. 07

Compressive

1 «.

ICS..-

0. fiO

One face- -

(Tl 240

292

280

Transverse - TS.

Concentrated .

Impact -

Average,

TS

274

One face J

1 PI

0. 004

003 '.m

lb 185

2P0

180 Average - --.

IPS

0. 005 218

One face

17/ 8.5

8.0

8. 5

\l2

Average

1/3 . -

8.3

End of top plate

verage

(Rl

Kipslft " 1.06

1.00

1.05

Racking m

RS

1, 04

First plaster failure by crushing near bottom plate. Rocking over of upper plate due to eccentric loading caused

plate to crush on compression side and pull away from

studs on tension side. Plaster cracked near bottom at 2.00 kips/ft. Final failure similar to specimen CI.

First jilaster crack at 0.!»6 kip/ft, fourth loading. Final fail- ure similar to specimen CI.

First plaster crack in lower face at 52 \h/lV at fifth loading. Failure due to cross grain tension in one outside stud

followed by horizontal shear in center stud.

First plaster crack in lower face at 49 lb/ft' at fifth loading. Failure by tension in studs.

First plaster crack in lower face at 48 lb/ft ' at fifth loading. Failure by tension in studs.

Average of two tests—220 and 150 lb for loads at joint and

center of width of lath, respectively. Loaded at joint between two laths. Loaded at center of width of lath.

First plaster crack on both faces at 3-ft drop. One outside stud broke at 2-in. knot at 8.5-ft drop.

First plaster crack in both faces at 2.5-ft drop. Brash tension in center stud and tension in one side stud at 8-ft drop.

First plaster crack in lower face at 2.5-ft drop and top face at

3.5-ft drop. Tension in center stud at 8.5-ft drop.

First plaster crack at 0.88 kip/ft at sixth loading. Final

failure due to plaster shearing keys.

First plaster crack at 0.38 kip/ft at fifth loading. Final

failure due to plaster shearing keys.

First plaster crack at 0.50 kip/ft at fifth loading. Final fail- ure due to plaster shearing keys.

"A kip is l,a)0 lb. Specimens loaded on top plate through knife edge at one-third width of frame from inside face of frame and supported at bottom on similar knife edge at center of frame. The results for wall specimens QA-Rl, R2,

and Its subjected to the racking test are given

in table 3 and in figure 17. Failure was characterized by the sheatliing

pulling the naUs and shearing from the lower

plate ' and by the studs breaking in bending or

splitting from the nails driven through the

lower plate into their ends.

VII. PARTITION 4;/;—LOAU-BEARING

] . Comments

Since nonload-bearmg partitions are usually

built the same as load-bearing partitions, no

nonload-bearing partitions were included.

' Sheathing was less securely nailed lo the lower or floor plate than to the upper. (See sec. VI-1.)

2. Description

The partitions were of the same construction

as the walls with the exception that both faces were lathed and plastered and the impact spec- imens QD-Il, 12, and 13 had single 2- by 4-in. top plates. As with the wall specimens, the

floor plate of each 8-ft partition specimen was

nailed to a 6- by 6-in. timber before plaster was

applied to the specimen.

3. Compressive Load

A partition specimen {QD~C3) untler compressive load is shown in figure 18. The operation of the testing machine was as described

for wall frames under section T"-3. The results for specimens QD-Cl, C2, and

C3 are shown in table 4 and in figures 19 and 20.

[15]
The average maximum load of 6.90 kips/ft is approximately 35 percent of the computed

value obtained by inserting in the Euler column

120

I:

in I

40

* —11

/'

1 —\—

—1

1

1

1 H

t

f

0 0.2 0.4 0.6

defleciion in. Figure 21.—Transverse load on partition QD.

Load-deflection (open circles) and load-set (solid circles) results for specimens QD-Tl. T2. and T3 on the span of 7 ft 6 in. Loads are in pounds per square foot of the area (span times the width of specimen 30 sq ft). formula the average value of stiffness derived

from the transverse-load tests on specimens

QD-Tl, T2, and T3.

The three specimens failed by crushing of the

plaster near the plates, crushing of the plates at the stud ends, tension plaster cracks after maximum load, and finally rocking over of the

upper plate allowing the studs to kick out, as shown in figure 18, without brealdng.

4. Transverse Load

The operation of the testing macliine was as described for wall frames under section V-4.

The results of transverse-load tests (speci- mens QD-Tl, T2, and T3) are given in table 4

and figure 21. First failure in these panels was by tension

in the plaster on the lower face. Final failure was by bending in the studs.

5. Concentrated Load

The results for specimens QD-Pl, P2, and

PS are given in table 4. Indentation on the

plaster was so influenced by crushing and cracking of the plaster that consistent load-indentation readings were not obtained. Consequently only the indentation at 100 lb was recorded.

Failure was by crushing and cracking of the

plaster and breaking of the laths.

6. Impact Load

A setup for an impact test on a partition

specimen is shown in figure 22.

Figure 22.

Partition specimen QD in position for impact-load lest.

[16]
The results for specimens QD-Il, 12, and 13

lire given in table 4 and figure 23. The three specimens failed by breaking of

the studs accompanied by shattering of the

plaster and brealdng of the laths.

7. Eacking Load

A partition specimen {QD~R1) under the

racking-load test is shown in figure 24. Tlio

8^ ^ , \ \ 1

racldng-load test was conducted as outlined for walls under section VI-6.

The results for specimens QD-Rl, R2, and

R3 are given in table 4 and figure 25. Final failure was due to shearing off of the

plaster keys, thus lowering the resistance to

distortion.

VIII. FLOOR QB

1. Description

Floor specimens (fig. 26) were 4 ft wide by

12)^ ft long and consisted of three 2- by 8-in.

joists (actual dimensions 1%6 by 7% in.) spaced

16 in. on centers and symmetrically placed with

respect to the width. A 2- by 8-in. by 4-ft header was fastened to each end of the speciFiGURE 24.

Partition specimen QD-Rl under raehiitg- load test. men by two 16d common wire nails driven into

the end of each joist. The subfloor, which was

applied in full-length pieces, was laid diagonally

at an angle of about 45° with the joists, and

nailed to each joist and header with two 8d

common nails. Building paper was laid between the subfloor and the finish floor, then one row of 1- by 4-in. cross bridging, each piece of

which was nailed at each end with two 8d nafls, was applied at midlength of the specimen.

The finish floor was laid 1 week before test and

nailed with 8d casing nails. The lower surface

[17]
was lathed, the joints being- broken for each

course of eight laths, and plastered.

2. Tkansverse Load

The operation of the testing- machine was as described for wall frames under section V-4,

1.0

0.8

en ^ 0.6

^0.4

0.2

0

•

1 oD—7-1 1—°n

^—

1 1

\ / •00/ c

' / w

1 QD

0 0.4 0.8

deformafion in./8f

f

Figure 25.

Racking load on partition QD.

Load-deformation (open circles) and load-set (solid circles) results for specimens QD-Rl, Re, and R3. Loads are in kips per foot nf the face width of specimen (8 ft 0 in). except that the rate of movement of the head was about 0.08 in./min, which was increased to 0.13 in./min in the final run to failure. The results for specimens QB-Tl, T2, and

T3 are given in table 5 and figure 27.

First failure was by cracking of the plaster at relatively low loads. Final failure was by

tension in the joists, influenced in specimens

T1 and T3 by knots.

3. Concentrated Load

The results for specimens QB-Pl, P2, and

PS are given in table 5 and figure 28. Failure was by local splitting and breaking

of the flooring and subflooring as the tool penetrated the floor panel.

4. Impact Load

The results for specimens QB-Il , 12, and 13

are given in table 5 and figure 29. The floor panels showed no failure in the

joists at the final drop from a height of 10 ft. The plaster broke loose very generally in the

central portion of specimens II and 12, and

only slightly at one edge of 13.

IX. ROOF QC

1. Description

Roof specimens (fig. 30) were 4 ft wide by

14 ft 6 in. long. They consisted of two 2- by

6-in. (actual 1%6 by 5%6 in.) rafters spaced 24

in. on centers and symmetrically placed with

respect to the width. A 2- by 6-in. header 4 ft long was fastened to each end of the specimen

by two 16d common wire nails driven into the

end of each joist. The roof boards were laid

snug, perpendicular to the rafters, and nailed

with two 8d nails at each rafter crossing and

were covered with building paper and shingles

laid with a 5-in. exposure.

\

Figure 26. —Under side of Jloni specimen QB before plastering, showing construction.

[18]
Table 5.

Structural properties of floor QB

[Weights of constructions and of plaster are shown in table 7. The average moisture content of the framing at test was 10.5 percent and the specific gravity (based on weight and volume when oven dry) was 0.50)

Load Load applied Specimen

designation

Maximum

height of drop»

Indentation at

100 lb Maximum

load Remarks

Transverse- XT pper faceTl.

Iblfl

TS.

242

259

358

Concentrated.

Impact

AverageUpper face

Average.

0. 000

.000

.000

lb

3, 500 3,320

3,610

0. 000 3, 477

Upper face.

10.0

' 10.0

' 10.0

First plaster crack at 2!) Ib/ft^ at third loading. Failure by

tension at knots in 2 joists. First jiliister crack at 31 lb/ft* at fourth loading. Failure by

tension in jui^ts. First iilaster crack at 39 lb/ft* at fourth loading. Failure by

tension in joists influenced by knots.

Loaded at center of flooring strip over joint in subfloor. Loaded at center of flooring strip over center of subfloor board. Do.

First plaster crack at 4.5-ft drop. No failure in flooring or

joists. First plaster crack at 4-ft drop. No failure in flooring or

joists. First plaster crack at 6.5-ft drop. No failure in flooring or

joists.

.\verage- . 10.0

a Test discontinued at 10-ft drop.

2. Transverse Load

The operation of the testing machine was as described for wall frames under section V-4,

except that the rate of movement of the head was 0.13 in./min and was doubled in the final run to failure. The results for specimens QC-Tl, T2, and

T3 are given in table 6 and figure 3 1

T.4BLE 6.

Structural properties of roof QC

[Weights of constructions and of plaster are shown in table 7. The aver- age moisture content of the rafters at test was 8.5 percent and the average specific gravity (based on weight and volume when oven dry) was 0.44]

3. Concentrated Load

The results for specimens QC-Pl, P2, and

P3 are given in table 6 and figure 32. m

Load

Transverse.

Concentrated.

Load

applied

'Upper

. face.

AverageUpper

face.

Average.

Speci- men

desig- nation

TlT2

TS

PI

PS

Indentation

at 100

lb

0. 000

.001

.001

0. 001

Maxi- mum

load

84.7

113. 2

74.0

lb 1,670

1, 760

1,350

1, 593

Remarks

Tension

rafters. Tension

rafter. Tension

raftersin both

in one

in both

I

.1

80

40

o J

-r

1 -H

1 H

1 • opo

1

11

i

IjT

•p QB

Load on one roof board only. Load at least 1 in. from joint in roof. Loaded over joint between two roof boards.

Figure 27.

OA 0.8

deflecfion in. -Transverse load on floor QB.

Failure was by tension in the rafters.

Load-deflection (open circles) and load-set (solid circles) results for specimens QB-Tl, T2, and TS on the span of 12 ft 0 in. Loads are in pounds per square foot of the area (span times the width of specimen

48 sq ft). Failure was by the test tool puncturing the

shingles and breaking through the roof board.

[19]
X. LOADS AND DEFLECTIONS IN

TRANSVERSE TESTS

Results of transverse tests on walls, partitions, floors, and roofs are expressed in this

3000

2000

^ 2000

5 mo

500

/

' w

I

1•

• 1 QB

0 0.01 0.02 0.03

indenfafion in. Figure 28.

Concentrated load on floor QB.

Load-indentation results for the specimens QB-Pl, P2, and PS.

report in terms of load per square foot of area although in test the load was applied at the

quarter points of the span and thus was not

uniformly distributed. The deflections re- corded were measured at midspan.

Maximum loads as found in the transverse

tests are practiciilly the same as would bo found

from tests with the load uniformly distributed.

The deflections in the earlier stages of the tests are 10 percent greater than would be caused by

uniformly distributed load of the same magnitude.

0.4 0.8

deflecflon in, Figure 29.

Impact load on floor QB.

Height of drop-deflection (open circles) and height of drop-set (solid

circles) results for specimens QB-Il, 12, and K on the span of 12 ft 0 in.

XI. SIGNIFICANCE OF SET READINGS

Readings of set in the compressive-, transverse-, impact-, and racking-load tests on all covered specimens were so influenced by friction

between the parts, closing of parts, and in some

instnnces crushing of the plaster or plates that

Figure ZQ.— Under side oj' roof specimen QC, showing construction.

[20]
they are of doubtful significance. For example,

in the transverse-load test the set reading

would in many instances entirely disappear

with a slight pressure momentarily applied

underneath the panel. Under the impact test, vibrations were set up, and when the panel came to rest it might be at either a low or a high

point in its amplitude, due to friction between

the various parts. The panel coming to rest at the high point would accoimt for the negative

Table 7. —Weights of conslructions ami iihiHlcr

80

«V4

I

60

40

fO

• o

O yCD

1

1• Oj •

Y

i2C 0 12 3

defiedion in. Figure 31.—Transverse load on roof QC.

Load-deflection (open circles) and load-.set (solid circles results for specimens QC-Tl, T2, and T3 on the span of 14 ft 0 in. Loads are in pounds per square foot of the area (span times the width of specimen

5B sq ft).

set obtained at a 10-ft height of drop in the

walls tested with the outside face up (fig. IG).

Xn. WEIGHTS

The weights of the various constructions

before plastering and at time of test have been

smnmarized in table 7. The weights of plaster were found by differencing the weights before

plastering and at tune of test, which was 28

days later. Change of weight of parts other

than plaster over this period was no doubt very

small and has been disregarded in deriving the

figures for weight of plaster.

Construction Weight

without

plaster

Weight

with

plaster

V/eit'ht of plaster (age 28 days)

Wall

Ib/p

5.

3.0

Ibip

10. 0 12.8

18. 2

Ib/p

4.9 Partition. 4. y Floor _ Roof . 4.6

1000

I

600

400

200

0

—# —•—

* /\

• —

V"

1»

1

1•

1•

1•

1•

1A

QC

0 0.1 0.2 0.5

indenfaiion in. Figure 32.

Concentrated load on roof QC.

Load-indentation results for specimens QC-Pl, PI, and P3.

XIII. TWO METHODS OF TESTING

WALLS UNDER COMPRESSIVE LOAD

1. Comments

In BMS2, Methods of Determining the

Structural Properties of Low-Cost House Constructions, p. 7, the compressive load is described as being apphed to the specuiien as a column having a flat end at the bottom. For

the reasons given in section III-3, Test Procedure, the walls and partitions tested for this

report were supported by a laiife-edge at the

bottom. To determine the effect of the type of

lower bearing on the residts for compressive

loading, specimens ZZ were tested in the laboratory of the National Bureau of Standards at Washington, D. C, using knife-edge and flat- end bearings at the bottom. They were built

[21]
under the supervision of a member of the staff of the Forest Products Laboratoiy who assisted

in the tests.

2. Description

Three specimens were made for each of the

two types of lower bearing. The framing for

these specimens consisted of 2- by 4-in. (nominal)

studs, a doubled 2- by 4-in. plate at the top,

and a single 2- by 4-ui. floor plate at the bottom.

These parts were arranged in lilve manner to the 4-ft wall specimens (QA) described under

section VI- 1. Douglas fir was used for the framing; and, in

order to avoid any effect of defects on the desired comparison, straight-grained material free from knots was selected. To further assure

valid comparison between tests with the two

kinds of end bearing the specimens were paired

in such a manner that studs cut from end-to-end

positions in a 2- by 10-in. plank, jointed straight,

and surfaced to width, occupied like positions

in the specimens of a pair and were oriented

alike, i. e., with the same end up and the same

edge toward the inside face of the specimen.

Floor plates and top-plate parts were similarly

matched. The frames were faced on both sides

with fiberboard in two pieces, with the

junction on the center stud. Each piece of

fiberboard was nailed to the top and floor plates

and to the center stud with 8d common nails

spaced 3 in. NaU spacing along the other studs was 6 in., 8d common nails being used on the

outside face of the specimen and 6d casing or

finish nails on the inside face.

3. Test Results

The data from the tests in series ZZ are given

in table 8. Table 8.

Results of compressive-load icsls on wall specimens ZZ comparing knife-edge to fiat-end bearing

Specimen des- ignation Bottom bear- ing

Maxi- mum

load

Lateral deflection midheight at

Shortening at—

12,000 lb20,000

lb

28,000 lb

12,000 lb20,000 lb

C!a Clb C2a

ceb C3a

Flat Knife edge

Flat Knife edge..

Flat

lb 28, 000

29. 000

32, 000

34. 000

25. 740

24. 500

in.

0. 12

.08 .02

.05

.03

.05

in.

0. 21 .16

.10 .12

.08

.18

in. 0.40

.32

.36

.38

in. 0.05

.06

.08

.08

.05

.06

in. 0.10

.11 .13 .12

.11 C3b. Knife edge. .15

.

Flat Knife edge.

.

Average

Average

28. 580

29, 170

0. 05

0. 06

0. 13

0. 15

0. 38

0. 35 0.060. 07

0.11

0. 13

In the tests of series ZZ, as well as in other

compressive-load tests of wood constructions

with 2- by 4-in. studs and doubled 2- by 4-in. top

^

plates, final failure was preceded by severe

eccentric crushing of the plate against the ends j i of the studs. (The eccentricity was so great in some instances that studs and plate were in contact over only part of the width, as shown

in fig. 1.)

I In the special tests with flat bearing at the

lower end of the specimen, eccentric yielding , also occurred at the bearing of studs on tli floor , plate and contributed to the eccentricity of , loading, although it was not great enough to be

apparent as visible crushing.

In many of the tests on specimens with

doubled 2- by 4-in. top plates the eccentric

crusliing of the under side of the plate against , the ends of the studs caused the plates to roll and carry the upper ends of the studs so far

laterally that "jack-knifing" or collapse of the

specimen and apparatus occurred, probably

without the fuU load capacity of the studs

being developed. This was true in the tests of

wall frames QAf (see fig. 1 and table 2) in partition specimens QD (see table 4) and in all but

one, Clb, of the wall specimens ZZ. For aU

the other specimens, lateral movement at the

top of the studs greatly increased the effective

eccentricity of loading.

4. Discussion

The tests on the ZZ specimens were carried

out subsequent to those described in preceding

parts of this report but in advance of any other

tests of wood constructions under this program, t On the basis of the results of tests on QA,

QD, and ZZ specimens and in order to obtain

uniformity with tests on other types, it was

decided that in all future compressive-load tests of wood constructions under this program flat bearing would be used at the lower end in

accordance with BMS2.

Considering the numerical results listed m \ table 8 and the behavior observed in tests of ! the ZZ series and other wood constructions, it

is improbable that the values from the present

tests on walls (QA), partitions (QD), and wall 1

frames differ significantly from those that i I would have resulted had flat bearings been

used. L|

122]
XIV. SELECTED REFERENCES

G. W. Trayer, Rigidity and strength of frame walls, Forest Products Laboratory Mimeograph R896

(1929); Eng. News-Record 103, 656-7 (1929). G. W. Trayer, Practical suggestions on frame house

constructions, President's Conference on Home Building and Home Ownership, Final Report of Committees 7, 79-93 (1932); Forest Products Laboratory

Mimeograph R991 (1932). G. W. Trayer, Plywood as a structural covering for frame

walls and wall units. Forest Products Laboratory

Mimeograph R1025 (1934) ; Eng. News-Record 113, 172-4 (1934). G. W. Trayer, Floor panels with stressed plywood covering, Forest Products Laboratory Mimeograph R1026

(1934), Eng. News-Record 113, 174-6 (1934). Madison, Wis., May 8, 1939.

o

Forest Products Laboratory Wood Handbook, fJasic information on wood as a material of construction with

data for its use in design and specifications, U. H. Department of Agriculture Pubhcation (193.5). R. F. Luxford, Fabricated wall panels with plywood

coverings, Forest Products Laboratory Mimeograph

R1099 (1936); Wood Products 41, 2, 8-10 (1936)- Timberman 37, 4, 22, 24-26 (1936); Abstract- American Builder 58, 9, 82, 114 (1936); Abstract: Architectural Record 79, 4, 334 (1936). G. E. Heck, Rigidity and strength of frame walls sheathed with fiberboard, Forest Products Laboratory Mimeograph R1151 (1937); Wood Construction 2

14-15, 23 (1939).

[23]



I

I BUILDING MATERIALS AND STRUCTURES REPORTS

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BMSl Research on Building Materials and Structures for Use in Low-Cost Housing 100 BMS2 Methods of Determining the Structural Properties of Low-Cost House Constructions 100 BMS3 SuitabiUty of Fiber Insulating Lath as a Plaster Base 100 BMS4 Accelerated Aging of Fiber Building Boards 100 BMS5 Structural Properties of Six Masonry Wall Constructions 150 BMS6 Survey of Roofing Materials in the Southeastern States 150 BMS7 Water Permeability of Masonry WaUs 100 BMS8 Methods of Investigation of Surface Treatment for Corrosion Protection of Steel 100 BMS9 Structural Properties of the Insulated Steel Construction Co.'s "Frameless-Steel" Constructions for Walls, Partitions, Floors, and Roofs 100 BMSIO Structural Properties of One of the "Keystone Beam Steel Floor" Constructions Sponsored by the H. H. Robertson Co 100 BMSll Structural Properties of the Curren Fabrihome Corporation's "Fabrihome" Constructions for Walls and Partitions 100 BMS12 Structural Properties of "Steelox" Constructions for Walls, Partitions, Floors, and Roofs

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Connecticut Pre-Cast Buildings Corporation 100 BMS21 Structural Properties of a Concrete-Block Cavity-Wall Construction Sponsored by the National Concrete Masonry Association 100 BMS22 Structural Properties of "Dun-Ti-Stone" Wall Construction Sponsored by the W. E. Dunn Manufactiu-ing Co 100 BMS23 Structural Properties of a Brick Cavity-Wall Construction Sponsored by the Brick

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