ASTM D7381-07(2021)e1
(Practice)Standard Practice for Establishing Allowable Stresses for Round Timbers for Piles from Tests of Full-Size Material
Standard Practice for Establishing Allowable Stresses for Round Timbers for Piles from Tests of Full-Size Material
SIGNIFICANCE AND USE
4.1 This practice is primarily intended for use by associations, third-party grading agencies, technical societies and other groups that develop national design standards and use recommendations for round timber piles.
4.2 This practice provides procedures for establishing compression parallel to grain and bending stresses for round timber piles including: sampling of material for testing; methods of test and property calculation procedures; distribution analysis of test data; procedures for determining adjustments for critical section location; pile oversize, load sharing and treatment; and procedures for deriving allowable stresses.
4.3 In using allowable stresses established under this practice, factors specific to each end use which may affect the performance of the pile system shall be considered by the designer. Such factors include the location of the critical section, the bearing capacity of the soil, the ability of the pile to withstand driving forces, the properties of the cap or load distributive element tying piles together and the loading and conditions of service.
SCOPE
1.1 This practice contains procedures for establishing allowable compression parallel to grain and bending stresses for round timbers used for piling, based on results from full-size tests.
Note 1: Allowable stresses for compression perpendicular to grain and shear properties are established in accordance with the provisions of Practice D2899.
1.2 Stresses established under this practice are applicable to piles conforming to the size, quality, straightness, spiral grain, knot, shake and split provisions of Specification D25.
1.3 A commentary on the practice is available from ASTM International.
1.4 The values stated in inch-pound units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
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Designation: D7381 − 07 (Reapproved 2021)
Standard Practice for
Establishing Allowable Stresses for Round Timbers for Piles
from Tests of Full-Size Material
This standard is issued under the fixed designation D7381; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
ε NOTE—ASTM Specification E3200 and IEEE/ASTM SI-10 were added to the Referenced Documents section and edito-
rial updates were made in Sections 3, 10.4 and 10.5 in December 2021.
1. Scope D9 Terminology Relating to Wood and Wood-Based Prod-
ucts
1.1 Thispracticecontainsproceduresforestablishingallow-
D25 Specification for Round Timber Piles
able compression parallel to grain and bending stresses for
D198 Test Methods of Static Tests of Lumber in Structural
round timbers used for piling, based on results from full-size
Sizes
tests.
D245 Practice for Establishing Structural Grades and Re-
NOTE1—Allowablestressesforcompressionperpendiculartograinand
lated Allowable Properties for Visually Graded Lumber
shear properties are established in accordance with the provisions of
Practice D2899.
D1036 Test Methods of Static Tests of Wood Poles
D1990 Practice for Establishing Allowable Properties for
1.2 Stresses established under this practice are applicable to
Visually-Graded Dimension Lumber from In-Grade Tests
piles conforming to the size, quality, straightness, spiral grain,
of Full-Size Specimens
knot, shake and split provisions of Specification D25.
D2555 PracticeforEstablishingClearWoodStrengthValues
1.3 A commentary on the practice is available from ASTM
D2899 Practice for Establishing Allowable Stresses for
International.
Round Timber Piles
1.4 The values stated in inch-pound units are to be regarded
D2915 Practice for Sampling and Data-Analysis for Struc-
as standard. No other units of measurement are included in this
tural Wood and Wood-Based Products
standard.
D3200 Specification and Test Method for Establishing Rec-
ommended Design Stresses for Round Timber Construc-
1.5 This standard does not purport to address all of the
tion Poles
safety concerns, if any, associated with its use. It is the
D4761 Test Methods for Mechanical Properties of Lumber
responsibility of the user of this standard to establish appro-
and Wood-Based Structural Materials
priate safety, health, and environmental practices and deter-
D6555 Guide for Evaluating System Effects in Repetitive-
mine the applicability of regulatory limitations prior to use.
Member Wood Assemblies
1.6 This international standard was developed in accor-
IEEE/ASTM SI-10 American National Standard for Metric
dance with internationally recognized principles on standard-
Practice
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
3. Terminology
mendations issued by the World Trade Organization Technical
3.1 Definitions:
Barriers to Trade (TBT) Committee.
3.1.1 For definitions of terms used in this standard, refer to
Terminology D9.
2. Referenced Documents
3.2 Definitions of Terms Specific to This Standard:
2.1 ASTM Standards:
3.2.1 allowable stress—numeric value of pile strength ap-
propriate for use in design.
This practice is under the jurisdiction of ASTM Committee D07 on Wood and 3.2.2 end-bearing—compression parallel to grain stress
is the direct responsibility of Subcommittee D07.04 on Pole and Pile Products.
used in design when the pile load is not carried to the soil
Current edition approved April 1, 2013. Published December 2021. Originally
through skin friction.
approved in 2007. Last previous edition approved in 2013 as D7381 – 07 (2013).
DOI: 10.1520/D7381-07R21E01.
3.2.3 load sharing—distribution of load that occurs in two
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
or more piles which are capped with a load-distributing
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
element that assures the piles deform as a group.
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. 3.2.3.1 Discussion—The load distributed to the piles in such
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D7381 − 07 (2021)
a group is in proportion to the stiffness of each pile. This 4. Significance and Use
distribution of loads to the piles in the group reduces the effect
4.1 This practice is primarily intended for use by
ofbetweenpilevariabilityandincreasessystemreliabilityover
associations, third-party grading agencies, technical societies
that of piles which perform as single members.
and other groups that develop national design standards and
3.2.4 skin friction—interaction between the pile surface and
use recommendations for round timber piles.
thesurroundingsoilwhichservestodistributeloadeitheraway
4.2 This practice provides procedures for establishing com-
from or into a pile.
pression parallel to grain and bending stresses for round timber
3.2.4.1 Discussion—A positive skin friction refers to pile
piles including: sampling of material for testing; methods of
loads distributed to the soil. Negative skin friction refers to
test and property calculation procedures; distribution analysis
loads being distributed into the pile as a result of soil
of test data; procedures for determining adjustments for critical
subsidence or consolidation.
section location; pile oversize, load sharing and treatment; and
3.3 Symbols:
2 procedures for deriving allowable stresses.
A = cross-sectional area of a round timber pile, in.
c = circumference of a round timber pile
4.3 In using allowable stresses established under this
C = conditioning adjustment
cp practice, factors specific to each end use which may affect the
C = adjustment for duration of load and miscellaneous
ds performance of the pile system shall be considered by the
factor of safety
designer. Such factors include the location of the critical
C = load sharing adjustment
ls section, the bearing capacity of the soil, the ability of the pile
C ,C ,C , and C , = adjustments to F , F , E and
oc ob oe oeb c b to withstand driving forces, the properties of the cap or load
EMOE for pile oversizing relative to Specification D25 speci-
distributive element tying piles together and the loading and
fied minimum circumferences
conditions of service.
C = adjustment of allowable compression parallel to grain
t
stress at pile tip to critical section location L
5. Sampling Full-Size Round Timbers
D = pile diameter
5.1 The population to be sampled shall be round timbers of
E = allowable modulus of elasticity in compression
a particular species or species group meeting the provisions of
E = modulus of elasticity for individual member individual
i
Specification D25. Only those species groups that do not
compression parallel to grain specimen
exceed the variability, as measured by the criteria of Section 5
E = average modulus of elasticity of butt and tip compres-
a
ofPracticeD2555,ofthemajorlumberspeciesgroupssampled
sion parallel to grain specimens from the same pile
in the In-Grade lumber testing program in the United States
E’ = sample mean modulus of elasticity in compression
andCanadashallbeconsideredasasinglespeciesforsampling
EMOE = effective modulus of elasticity in bending for an
i
and analysis purposes. For species groups exceeding these
individual pile
variability limits, the species composition should be changed
EMOE’ = sample mean effective modulus of elasticity in
such that the limits will be met by the remaining species in the
bending
group if sampling of the group as a single species is desired.
EMOE = allowable effective modulus of elasticity in bend-
ing NOTE 2—See X9.1 of Practice D1990 for discussion of in-grade
samplingofspeciesgroups.MajorspeciesgroupssampledintheIn-Grade
F = allowable stress in bending
b
lumber testing program are given in Note 3 of Practice D1990.
F = allowable stress in compression parallel to grain
c
f = compression parallel to grain 5 % tolerance limit with
5.2 A representative sample (n) of all sizes (diameters) and
cTL
75 % confidence determined from test results for the tip
lengths of timber piles as in Tables X1.2 or X1.3 and
specimen
Tables X1.4 or X1.5 of Specification D25 shall be selected for
f = bending 5 % tolerance limit with 75 % confidence
thespeciesorspeciesgroupbeingevaluated.Samplingbysize,
bTL
determined from test results
length and class shall be in proportion to total production and
L = distance from pile tip to critical section, ft
shall be distributed across plants representative of the produc-
L = distance from top of butt compression parallel to grain
ing region.
e
test specimen to top of tip compression parallel to grain test
NOTE 3—Specification D25 pile specifications provide for only one
specimen, ft grade and quality level.
MORBP = modulus of rupture at breakpoint
5.3 Individual piles selected as test material shall be green
k = number of random variables used in random products
and randomly chosen from inventory in the yard at each plant.
simulation
n = numberofpilesinaspeciesorspeciesgroupselectedfor 5.4 Sample size shall be based on the principles of Practice
testing D2915 and shall be sufficient to provide reliable estimates of
p = exponent of L used to calculate pile length effect on the distributions of bending and compression parallel to grain
e
compression strength strengths of timbers of the species or species group being
r = radius of gyration = D/4 evaluated.Eachpileselectedfortestshallbeevaluatedforboth
S = section modulus of a round timber pile, in. bending and compression strength with compression speci-
UCS = ultimate compressive strength
mens being cut from the butt and tip ends after the bending test
z = number of piles in a cluster is completed.
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D7381 − 07 (2021)
6. Test Methods and Calculation Procedures 7.1.4 The diameters of the small and large ends of the butt
and tip compression parallel to grain test specimens selected
6.1 All test members shall be maintained in a green condi-
from each pile and the maximum individual knot size and the
tion prior to test.
maximum sum of knot diameters in any one-foot of length in
6.2 Each member shall be tested in bending in accordance
each of these specimens.
with the procedures of Test Methods D1036. Modulus of
7.1.5 Slenderness ratios, rate of load application, time to
rupture at breakpoint (MORBP) and effective modulus of
maximum load, section properties, specific gravity, formulas
elasticity in bending (EMOE) shall be calculated in accordance
used to calculate strength and stiffness properties and other
with the formulas given in 19.4 of Test Methods D1036.Ifan
information as required by the provisions of Test Methods
alternative formula is used to calculate EMOE, its derivation
D198 and D1036.
and assumptions shall be documented.
7.1.6 Acomplete description of the analytical methods used
NOTE 4—The cross-section of round timbers varies from butt to tip as
to develop the statistics and factors described in Sections8–
a result of taper. A linear taper between butt and tip is assumed in the
11.
derivation of the EMOE equation. As tree tapers may not be linear but
parabolic, the moment of inertia of the resisting cross-section is underes-
timated and the resulting bending EMOE value for the pile is typically 8. Analysis of Test Data
substantially higher than the average E based on compression parallel to
8.1 The average of the individual pile EMOE and E values
i a
grain tests.
shall be calculated as the sample mean values (EMOE’ and E’)
6.3 After completion of the bending test, compression test
for the species or species group evaluated.
specimens shall be cut from the butt and tip ends of the
8.2 The distributions of UCS values for the tip compression
member. These specimens shall be prepared and tested in
specimens and the MORBP values for the n piles in the sample
accordance with Sections 12–19 of Test Methods D198. The
shall be examined to determined what type of distribution
same slenderness ratio, specimen length divided by the small
(normal, lognormal or nonparametric) best describes each data
end radius of gyration (r), shall be used for the butt and tip
set, particularly the lower strength values in the sample.
specimens but shall not exceed 17. Specific gravity disks shall
becutfromthebottomandtopofeachpile,immediatelyabove 8.3 If a parametric distribution is to be used, the mean,
the small end of the compression test specimens.
standard deviation and 5 % tolerance limit with 75 % confi-
dence (f or f ) determined for the property and sample
cTL bTL
6.4 To prevent excessive end crushing, the compression
using the methods of sections 3.4.3.2, 4.5, and Table 1 of
specimensshallbebandedortheendsair-driedpriortotesting.
Practice D2915.
Load-deformationdatashallbeobtainedforbothspecimens.In
place of the testing speeds specified in section 17.3 of Test 8.4 If a nonparametric distribution is to be used, the sample
Methods D198, a rate of straining (in./in. per min) such that test values shall be arranged in ascending order and the mth
maximum load is obtained between 1 and 5 min shall be used order statistic selected as the sample 5 % tolerance limit with
andbothbuttandtipspecimensshallbetestedatthesamerate. 75 % confidence (f or f ) in accordance with 4.5.4, 4.5.5,
cTL bTL
NOTE 5—A range of 1 to 5 min in failure times is within the range of and Table 2 of Practice D2915.
10 s to 10 min specified for in-grade testing of lumber in section 34.4 of
Test Methods D4761.
9. Critical Section Located Above the Pile Tip
6.5 Ultimate compression strength (UCS) and modulus of
9.1 Paired butt and tip compression parallel to grain UCS
elasticity (E) shall be calculated for both the butt and tip
i
values shall be used to establish an equation for adjusting tip
specimens using the area of the small end of each specimen.
compression allowable design values (F ) when the critical
c
Values of E shall be based on the linear portion of the
i
section is located above the tip as a result of skin friction.
load-deformationcurveswithsuitableadjustmentmadeforany
9.2 For each test pile, the difference between butt and tip
nonlinearity occurring at the beginning of the test.The average
UCS values shall be normalized using the following calcula-
of the E values for the butt and tip spe
...
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