ASTM D6513-21

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it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
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Designation: D6513 − 14 D6513 − 21
Standard Practice for
Calculating the Superimposed Load on Wood-frame Walls
for Standard Fire-Resistance Tests
This standard is issued under the fixed designation D6513; 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.
1. Scope
1.1 This practice covers procedures for calculating the superimposed axial load required to be applied to load-bearing wood-frame
walls throughout standard fire-resistance and fire and hose-stream tests.
1.2 The calculations determine the maximum load allowed by design for wood-frame wall assemblies under nationally recognized
structural design criteria.
1.3 This practice is only applicable to those wood-frame assemblies for which the nationally recognized structural design criteria
is are contained in the National Design Specification for Wood Construction (NDS).
1.4 The system of units to be used is that of the nationally recognized structural design criteria. For the NDS, the units are
inch-pound.
1.5 The text of this standard references notes and footnotes which provide explanatory material. These notes and footnotes
(excluding those in tables and figures) shall not be considered as requirements of the standard.
1.6 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.7 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.
2. Referenced Documents
2.1 ASTM Standards:
D9 Terminology Relating to Wood and Wood-Based Products
E119 Test Methods for Fire Tests of Building Construction and Materials
E176 Terminology of Fire Standards
E1529 Test Methods for Determining Effects of Large Hydrocarbon Pool Fires on Structural Members and Assemblies
This practice is under the jurisdiction of ASTM Committee D07 on Wood and is the direct responsibility of Subcommittee D07.05 on Wood Assemblies.
Current edition approved Oct. 1, 2014July 1, 2021. Published November 2014August 2021. Originally approved in 2000. Last previous edition approved in 20082014 as
D6513 – 08.D6513 – 14. DOI: 10.1520/D6513-14.10.1520/D6513-21.
Available from American Forest & Paper Association, American Wood Council, 1111 19th Street, NW, Suite 800, Washington, DC 20036Wood Council, 222 Catoctin
Circle SE, Suite 201, Leesburg, VA 20175
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6513 − 21
2.2 Other Standards:
NDSANSI/AWC–2018—National Design Specification for Wood Construction National Design Specification (NDS) for Wood
Construction
NDS Supplement—Design Values for Wood Construction Design Values for Wood Construction
3. Terminology
3.1 Definitions—Definitions used in this practice are in accordance with Terminology D9 and Terminology E176, unless otherwise
indicated.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 effective column length, n—unbraced length of the vertical member, adjusted for end conditions.
3.2.2 gross cross-sectional area, n—section area area of cross section calculated from overall actual dimensions of member.
3.2.2.1 Discussion—
For lumber, gross cross-sectional area is based on the standard dressed size of the member as given in the NDS Supplement for
the nominal size member.
3.2.3 net section area, n—section area area of cross section calculated by deducting from the gross sectioncross-sectional area the
projected area of all materials removed by boring, grooving, dapping, notching, or other means.
3.2.3.1 Discussion—
For nailed or screwed connections, the net section area equals the gross cross-sectional area.
3.2.4 superimposed load, n—The additional external load needed to be applied to the assembly to result in the calculatedduring
the test to achieve the required stresses within the assembly whenafter any dead load of the assembly itself is accounted for in the
calculations.
4. Significance and Use
4.1 Test Methods E119 and E1529, and other standard fire resistance test methods specify that throughout exposures to fire and
the hose stream, a constant superimposed axial load be applied to a load-bearing test specimen to simulate a maximum load
condition. They These test methods specify that this superimposed load shall be as nearly as practicable the maximum allowable
axial design load allowed by design under nationally recognized structural design criteria. For this practice, the nationally
recognized structural design criteria is the National Design Specification (NDS) for Wood Construction (NDS).
4.1.1 Alternatively, the standard fire resistance test methods shall be conducted by applying an axial load that is less than the
maximum allowable axial design load as addressed by the NDS and this practice, but these tests shall be identified in the test report
as being conducted under restricted load conditions. The superimposed axial load, as well as the superimposed axial load as a
percentage of the maximum allowable axial design load as addressed by the NDS and this practice shall be included in the test
report.
4.1.2 The superimposed axial load, as well as the superimposed axial load as a percentage of the maximum allowable axial design
load for the stud and as a percentage of the maximum allowable design load for the plate, shall be calculated using the Allowable
Stress Design (ASD) method in the NDS and this practice shall be included in the test report.
NOTE 1—The NDS should be used to ensure calculation of the superimposed load is in compliance with all applicable provisions of that document.
Appendix X1 describes how to calculate the superimposed load in accordance with the NDS.
4.2 This practice describes procedures for calculating the superimposed axial load to be applied in standard fire resistance tests
of wood-frame wall assemblies.
4.3 Statements in either the fire resistance test method standard or the nationally recognized structural design standard
supercedesupersede any procedures described by this practice.
4.4 The NDS shall be consulted to ensure calculations are in compliance with all applicable provisions of that document.
D6513 − 21
5. Test Assumptions
5.1 Wood-frame walls consist of vertical compression members and horizontal plates.
5.1.1 Compression members support a vertical axial load.
5.1.2 Bearing ends of the compression members are supported by the horizontal plates.
5.2 Load:
5.2.1 The test load is determined from the vertical axial capacity of the wall.
5.2.2 The test load calculations are based on standard design conditions including normal load duration, that is, ten years load
duration.
5.3 Dimensions:
5.3.1 Gross cross-sectional areas are the section areas based on the standard dressed size of the member as given in the NDS for
the nominal size member.
5.3.1.1 Net section area, A, is the gross area minus the projected area of all materials removed by boring, grooving, dapping,
notching, or other means.
5.3.1.2 For nailed connections, the net section area equals the gross section area.
5.3.2 Height of vertical columns is the actual length of the vertical member.
6. Design Load Calculations
6.1 For structural sawn lumber, reference design values for the grade and species of lumber are multiplied by all applicable
adjustment factors to determine the allowable design values.
6.1.1 Reference design values F , F , and E (E is reference design value in pre-2005 editions of the NDS) are given in the
C' C min
separate Supplement to the NDS.NDS Supplement.
6.1.2 Compression perpendicular to grain, F , is multiplied by C ,C ,C and C .
C' M t i b
6.1.3 Compression parallel to the grain, F , is multiplied by C ,C , C , C , C , and C .
C D M t F i P
6.1.4 Modulus of elasticity, E,E , is multiplied by C ,C ,C , and C .
min M t i T
6.2 Adjustment Factors for Design Values:
6.2.1 If values less than those listed in this section (6.2) are used for the adjustment factors, the appropriate load restriction shall
be reported in the test report.
6.2.2 Load duration factor, C , is 1.0.
D
6.2.3 Wet service factor, C , is 1.0.
M
NOTE 2—The results of testing with C = 1.0 can be conservatively applied for walls used in wet-service conditions. Where test results are limited to
M
walls used in wet-service conditions, a reduced load consistent with the application of the wet service factor is appropriate. For both cases, wall framing
is tested in the dry condition, because in-service moisture conditions for wood designed for wet service typically vary significantly ranging from dry to
wet depending on the season and application.
6.2.4 Temperature factor, C , is 1.0.
t
D6513 − 21
NOTE 3—The results of testing with load determined based on C = 1.0 may be conservatively applied for walls used in elevated temperature conditions.
t
6.2.5 Size factor, C , is taken from tables in the NDS.
F
6.2.5.1 Size factor for F and the appropriate table within NDS depends on the width, species, and grade of the lumber.
C
6.2.6 Incising factor, C , is 1.0.1.0, unless incised lumber is used for the wall framing. Where incised lumber is used, the incising
i
factor, C , shall be in accordance with the NDS.
i
6.2.7 Column stability factor, C .
P
6.2.7.1 Buckling of compression member in plane of wall is prevented by the sheathing which normally provides support
throughout its length and C equals 1.1.0.
P
6.2.7.2 For buckling of compression member perpendicular to plane of wall, C depends on the slenderness ratio of the columns.
P
The equation for C is given in the NDS. The effective column length shall be the actual length of the vertical member for
P
calculating the slenderness ratio and C .
P
NOTE 4—The effective column length used for the buckling calculation is the stud length (exclusive of the top and bottom plates) and is determined
assuming a column pinned at both ends, which is consistent with typical design assumptions for loadbearing wall studs.
6.2.8 Buckling stiffness factor, C , is 1.0.
T
6.2.9 Bearing area factor, C , is 1.0.
b
NOTE 5—The NDS provides for a bearing area factor of 1.25 for a bearing length of 1.5 in. when the bearings are not nearer than 3 in. to the end of a
member. Due to the random layup of platform framing, the location of butt joints in top and bottom plates cannot be specified. For this reason, the bearing
area increase is not generally taken in the design of wood frame walls. Historically, a bearing area factor of one has been used in the calculations of the
load for fire resistance tests of wood-frame walls.
6.2.10 For lumber and structural-glued laminated timber pressure-treated with fire-retardant chemicals, the allowable design
values, including connection design values, shall be obtained from the company providing the treatment and redrying service.
6.2.11 For load duration factor, C , equal to 1.0, there is no additional reduction for wood products pressure treated by an
D
approved process and preservative.
6.3 For vertical compression members of simple solid wood columns, the load per vertical compression member is the maximum
superimposed load that satisfies the following:
6.3.1 Actual compression stress parallel to grain based on minimum net section area does not exceed the reference compression
design value parallel to grain multiplied by all applicable adjustment factors except the column stability factor, C .
P
6.3.2 Actual compression stress parallel to grain based on gr
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