ASTM D7199-20

Standard Practice for Establishing Characteristic Values for Reinforced Glued Laminated Timber (Glulam) Beams Using Mechanics-Based Models

ABSTRACT
This practice covers mechanics-based models for calculating characteristic values for the strength and stiffness of reinforced structural glued laminated timbers (glulam). The mechanics-based analyses shall account for the following: (1) stress-strain relationships for wood laminations and reinforcement; (2) strain compatibility; (3) equilibrium; (4) variability of mechanical properties; (5) volume effects; (6) finger-joint effects; (7) laminating effects; and (8) stress concentrations at the termination of reinforcement in beams with partial length reinforcement. This practice also provides for minimum physical test requirements to validate mechanics-based models. A minimum set of performance-based durability test requirements for reinforced glulams is also herein described. Additional durability test requirements shall be considered in accordance with the specific end-use environment.
SCOPE
1.1 This practice describes procedures for establishing the characteristic values for reinforced structural glued-laminated timber (glulam) beams using mechanics-based models and validated by full-scale beam tests. Glulam beams shall be manufactured in accordance with applicable provisions of ANSI A190.1.  
1.2 This practice also describes a minimum set of performance-based durability test requirements for reinforced glulam beams, as specified in Annex A1. Additional durability test requirements shall be considered in accordance with the specific end-use environment. Appendix X1 provides an example of a mechanics-based methodology that satisfies the requirements set forth in this practice.  
1.3 This practice is limited to procedures for establishing flexural properties (modulus of rupture, MOR, and modulus of elasticity, MOE) about the x-x axis of horizontally-laminated reinforced glulam beams.  
1.4 The establishment of secondary properties, such as bending about the y-y axis, shear parallel to grain, tension parallel to grain, compression parallel to grain, and compression perpendicular to grain, for the reinforced glulam beams are beyond the scope of this practice.
Note 1: When the establishment of secondary properties is deemed necessary, testing according to other applicable methods, such as Test Methods D143 and D198 or analysis in accordance with Practice D3737, may be considered.  
1.5 Reinforced glulam beams subjected to axial loads are outside the scope of this practice.  
1.6 Proper safety, serviceability, and adjustment factors including duration of load, to be used in design are outside the scope of this practice.  
1.7 Evaluation of unbonded, prestressed, and shear reinforcement is outside the scope of this practice.  
1.8 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. The mechanics-based model shall be permitted to be developed using SI or inch-pound units.  
1.9 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.  
1.10 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

• Status: Published
• Publication Date: 31-Jul-2020
• ICS: 79.060.99 - Other wood-based panels
• Technical Committee: D07 - Wood
• Drafting Committee: D07.02 - Lumber and Engineered Wood Products

Relations

• Replaces: ASTM D7199-07(2012) - Standard Practice for Establishing Characteristic Values for Reinforced Glued Laminated Timber (Glulam) Beams Using Mechanics-Based Models
• Effective Date: 01-Aug-2020
• Refers: ASTM D143-23 - Standard Test Methods for Small Clear Specimens of Timber
• Effective Date: 15-Nov-2023
• Refers: ASTM D3737-18(2023)e1 - Standard Practice for Establishing Allowable Properties for Structural Glued Laminated Timber (Glulam)
• Effective Date: 01-Oct-2023
• Refers: ASTM D1990-19 - Standard Practice for Establishing Allowable Properties for Visually-Graded Dimension Lumber from In-Grade Tests of Full-Size Specimens
• Effective Date: 01-Oct-2019
• Refers: ASTM D4761-19 - Standard Test Methods for Mechanical Properties of Lumber and Wood-Based Structural Materials
• Effective Date: 01-Apr-2019
• Refers: ASTM D4761-18 - Standard Test Methods for Mechanical Properties of Lumber and Wood-Based Structural Materials
• Effective Date: 01-Nov-2018
• Refers: ASTM D2559-12a(2018) - Standard Specification for Adhesives for Bonded Structural Wood Products for Use Under Exterior Exposure Conditions
• Effective Date: 01-Aug-2018
• Refers: ASTM D3737-18 - Standard Practice for Establishing Allowable Properties for Structural Glued Laminated Timber (Glulam)
• Effective Date: 01-Apr-2018
• Refers: ASTM D3737-18e1 - Standard Practice for Establishing Allowable Properties for Structural Glued Laminated Timber (Glulam)
• Effective Date: 01-Apr-2018
• Refers: ASTM D1990-16 - Standard Practice for Establishing Allowable Properties for Visually-Graded Dimension Lumber from In-Grade Tests of Full-Size Specimens
• Effective Date: 01-May-2016
• Refers: ASTM D1990-14 - Standard Practice for Establishing Allowable Properties for Visually-Graded Dimension Lumber from In-Grade Tests of Full-Size Specimens
• Effective Date: 15-Feb-2014
• Refers: ASTM D198-14e1 - Standard Test Methods of Static Tests of Lumber in Structural Sizes
• Effective Date: 01-Feb-2014
• Refers: ASTM D198-14 - Standard Test Methods of Static Tests of Lumber in Structural Sizes
• Effective Date: 01-Feb-2014
• Refers: ASTM D198-13 - Standard Test Methods of Static Tests of Lumber in Structural Sizes
• Effective Date: 01-Oct-2013
• Refers: ASTM D4761-13 - Standard Test Methods for Mechanical Properties of Lumber and Wood-Base Structural Material
• Effective Date: 01-Apr-2013

Overview

ASTM D7199-20 establishes a standard practice for calculating the strength and stiffness characteristic values for reinforced glued laminated timber beams (glulam) using mechanics-based models, and validating these models with full-scale beam tests. This standard addresses the analytical determination of key flexural properties-specifically, modulus of rupture (MOR) and modulus of elasticity (MOE)-for glulam beams reinforced with high-strength materials such as fiber-reinforced polymers (FRP) or steel. It plays a crucial role in supporting the safety and reliability of engineered wood structures by setting requirements for both analytical models and physical testing.

Key Topics

• Mechanics-Based Modeling: The standard outlines requirements for mechanics-based analytical models used to predict characteristic values for the strength and stiffness of reinforced glulam beams. These models must comprehensively account for stress-strain relationships, strain compatibility, equilibrium, property variability, volume effects, finger-joint effects, laminating effects, and stress concentrations, especially where reinforcement is terminated within the beam span.

• Validation Through Testing: To ensure real-world reliability, ASTM D7199-20 mandates the validation of models through full-scale beam tests. It specifies minimum test matrix requirements for different wood species and reinforcement ratios, ensuring that model predictions are substantiated by physical data.

• Durability and Performance Requirements: The standard describes the minimum set of performance-based durability test requirements for reinforced glulam beams, considering anticipated end-use environments and long-term exposure conditions.

• Scope Limitations: While comprehensive for flexural properties about the principal axis (x-x), this standard excludes secondary properties such as bending about the minor axis, shear, and compression or tension parallel to the grain, as well as the evaluation of unbonded, prestressed, or shear-specific reinforcement.

Applications

ASTM D7199-20 is widely applicable in the structural engineering and construction sectors, especially for:

• Design and Manufacture of Reinforced Glulam Beams: Glulam beams reinforced with FRP or steel are used in bridges, buildings, and critical infrastructure. Following this standard ensures consistent and predictable structural performance.

• Product Qualification and Certification: Manufacturers can use the standard to qualify new glulam products and document compliance through validated mechanical modeling and testing.

• Quality Control in Engineered Wood Products: The requirements for periodic evaluation and ongoing process control help maintain the integrity and performance of laminated timber beams throughout their service life.

• Structural Retrofits and Upgrades: For the reinforcement of existing structures, mechanics-based models validated per ASTM D7199-20 provide a solid analytical basis for design decisions.

• Research and Development: The standard supports innovation in engineered timber construction by providing clear methodologies for the adoption of new reinforcement materials and configurations.

Related Standards

To give a holistic perspective on reinforced glulam beam design and testing, it is often helpful to reference related standards such as:

• ANSI A190.1 – Structural Glued Laminated Timber
• ASTM D3737 – Establishing Properties for Structural Glued Laminated Timber
• ASTM D143 – Test Methods for Small Clear Specimens of Timber
• ASTM D198 – Static Tests of Lumber in Structural Sizes
• ASTM D2559 – Specification for Adhesives for Structural Wood Products
• ASTM D4761 – Mechanical Properties of Lumber and Wood-Based Structural Materials
• ASTM D3039/D3410 – Tensile and Compressive Properties of Polymer Matrix Composites

By utilizing ASTM D7199-20 alongside these related standards, professionals can ensure robust, safe, and durable designs in engineered timber construction applications.

Keywords: ASTM D7199-20, glulam, glued laminated timber, reinforced beams, mechanics-based models, fiber-reinforced polymer, FRP, beam testing, modulus of rupture, modulus of elasticity, engineered wood, wood reinforcement, standard practice, timber construction, durability testing.

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.
Designation: D7199 − 20
Standard Practice for
Establishing Characteristic Values for Reinforced Glued
Laminated Timber (Glulam) Beams Using Mechanics-Based
Models
This standard is issued under the fixed designation D7199; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 1.7 Evaluation of unbonded, prestressed, and shear rein-
forcement is outside the scope of this practice.
1.1 This practice describes procedures for establishing the
characteristic values for reinforced structural glued-laminated 1.8 The values stated in inch-pound units are to be regarded
as standard. The values given in parentheses are mathematical
timber (glulam) beams using mechanics-based models and
validated by full-scale beam tests. Glulam beams shall be conversions to SI units that are provided for information only
and are not considered standard. The mechanics-based model
manufactured in accordance with applicable provisions of
ANSI A190.1. shall be permitted to be developed using SI or inch-pound
units.
1.2 This practice also describes a minimum set of
1.9 This standard does not purport to address all of the
performance-based durability test requirements for reinforced
safety concerns, if any, associated with its use. It is the
glulam beams, as specified in AnnexA1.Additional durability
responsibility of the user of this standard to establish appro-
test requirements shall be considered in accordance with the
priate safety, health, and environmental practices and deter-
specific end-use environment. Appendix X1 provides an ex-
mine the applicability of regulatory limitations prior to use.
ample of a mechanics-based methodology that satisfies the
1.10 This international standard was developed in accor-
requirements set forth in this practice.
dance with internationally recognized principles on standard-
1.3 This practice is limited to procedures for establishing
ization established in the Decision on Principles for the
flexural properties (modulus of rupture, MOR, and modulus of
Development of International Standards, Guides and Recom-
elasticity, MOE) about the x-x axis of horizontally-laminated
mendations issued by the World Trade Organization Technical
reinforced glulam beams.
Barriers to Trade (TBT) Committee.
1.4 The establishment of secondary properties, such as
bending about the y-y axis, shear parallel to grain, tension 2. Referenced Documents
parallel to grain, compression parallel to grain, and compres-
2.1 ASTM Standards:
sion perpendicular to grain, for the reinforced glulam beams
D9Terminology Relating to Wood and Wood-Based Prod-
are beyond the scope of this practice.
ucts
D143Test Methods for Small Clear Specimens of Timber
NOTE 1—When the establishment of secondary properties is deemed
necessary, testing according to other applicable methods, such as Test
D198Test Methods of Static Tests of Lumber in Structural
Methods D143 and D198 or analysis in accordance with Practice D3737,
Sizes
may be considered.
D905Test Method for Strength Properties of Adhesive
1.5 Reinforced glulam beams subjected to axial loads are
Bonds in Shear by Compression Loading
outside the scope of this practice.
D1990Practice for Establishing Allowable Properties for
Visually-Graded Dimension Lumber from In-Grade Tests
1.6 Proper safety, serviceability, and adjustment factors
of Full-Size Specimens
including duration of load, to be used in design are outside the
D2559Specification for Adhesives for Bonded Structural
scope of this practice.
Wood Products for Use Under Exterior Exposure Condi-
tions
This practice is under the jurisdiction ofASTM Committee D07 on Wood and
is the direct responsibility of Subcommittee D07.02 on Lumber and Engineered
Wood Products. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Aug. 1, 2020. Published August 2020. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 2006. Last previous edition approved in 2012 as D7199–07 (2012). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D7199-20. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7199 − 20
D2915Practice for Sampling and Data-Analysis for Struc- 3.2.9 reinforcement—lamination or material that is not a
tural Wood and Wood-Based Products conventional wood lamstock and having a mean longitudinal
D3039/D3039MTest Method forTensile Properties of Poly- ultimate tensile and compressive strength greater than 20 ksi
mer Matrix Composite Materials (138 MPa) and a mean tension and compression MOE greater
D3410/D3410MTest Method for Compressive Properties of than 3000 ksi (20.7 GPa).
Polymer Matrix Composite Materials with Unsupported
3.2.9.1 Discussion—Examples of acceptable reinforcing
Gage Section by Shear Loading
materials include fiber-reinforced polymer (FRP) plates and
D3737Practice for Establishing Allowable Properties for
bars,metallicplatesandbars,FRP-reinforcedlaminatedveneer
Structural Glued Laminated Timber (Glulam)
lumber (LVL), and FRP-reinforced parallel strand lumber
D4761Test Methods for Mechanical Properties of Lumber
(PSL).
and Wood-Based Structural Materials
3.2.10 tensile reinforcement—reinforcement placed on the
D5124Practice for Testing and Use of a Random Number
tension side of a flexural member.
Generator in Lumber and Wood Products Simulation
3.3 Symbols:
2.2 Other Standard:
Arm=moment arm, distance between compressive and ten-
ANSI A190.1Structural Glued Laminated Timber
sile force couple applied to beam cross-section
3. Terminology
b=beam width
C=total internal compressive force within the beam cross-
3.1 Definitions—Standard definitions of wood terms are
section (see Fig. A2.2)
given inTerminology D9 and standard definitions of structural
CFRP=carbon fiber reinforced polymer
glued laminated timber terms are given in Practice D3737.
d=beam depth
3.2 Definitions of Terms Specific to This Standard:
E=long-span flatwise-bending modulus of elasticity for
3.2.1 bonded reinforcement—reinforcing material that is
wood lamstock (Test Methods D4761; also see Fig. A2.1)
continuously attached to a glulam beam through adhesive
F =allowable bending stress parallel to grain
b
bonding.
F =internal horizontal force on the beam cross-section (see
x
3.2.2 bumper lamination—wood lamination continuously
Eq A2.2)
bonded to the outer side of reinforcement.
GFRP=Glass fiber-reinforced polymer
3.2.3 compressive reinforcement—reinforcement placed on
LTL=lower tolerance limit with 75 % confidence
the compression side of a flexural member.
M =external moment applied to the beam cross-
applied
3.2.4 conventional wood lamstock—solid sawn wood lami-
section
nations with a net thickness of 2 in. or less, graded either
M =internal moment on the beam cross-section
internal
visually or through mechanical means, finger-jointed and
MC=moisture content (%)
face-bonded to form a glulam.
MOE=modulus of elasticity
3.2.5 development length—length of the bond line along the
MOR=modulus of rupture
axisofthebeamrequiredtodevelopthedesigntensilestrength
MOR =5% one-sided lower tolerance limit for modulus
5%
of the reinforcement.
of rupture, including the volume factor
3.2.6 fiber-reinforced polymer (FRP)—composite material MOR =5% one-sided lower tolerance limit for modu-
BL5 %
consisting of at least two distinct components: reinforcing lus of rupture corresponding to failure of the bumper
fibers and a binder matrix (a polymer). lamination, including the volume factor
m*E=downward slope of bilinear compression stress-strain
3.2.6.1 Discussion—The reinforcing fibers may be either
curve for wood lamstock (see Fig. A2.1)
synthetic (for example, glass), metallic, or natural (for
N.A.=neutral axis
example, wood), and may be long and continuously-oriented,
T=total internal tensile force within the beam cross-section
or short and randomly oriented. The binder matrix may be
(see Fig. A2.2)
either thermoplastic (for example, polypropylene or nylon) or
UCS=ultimate compressive stress parallel to grain
thermosetting (for example, epoxy or vinyl-ester).
UTS=ultimate tensile stress parallel to grain
3.2.7 laminating effect—apparent increase of lumber lami-
Y=distance from extreme compression fiber to neutral axis
nation tensile strength because it is bonded to adjacent lami-
(see Fig. A2.2)
nations within a glulam beam.
y=distance from extreme compression fiber to point of
3.2.7.1 Discussion—This apparent increase may be attrib-
interest on beam cross-section (see Fig. A2.2)
uted to a redirection of stresses around knots and grain
ε =strain at extreme compression fiber of beam cross-
c
deviations through adjacent laminations.
section (see Fig. A2.2)
3.2.8 partial length reinforcement—reinforcement that is
ε =compressive strain at lamstock failure (see Fig.A2.1)
cult
terminated within the length of the glulam.
ε =compressive yield strain at lamstock UCS (see Fig.
cy
A2.1)
3 ε =tensile strain at lamstock failure (see Fig. A2.1)
tult
Available from APA – The Engineered Wood Association, 7011 South 19th
Street, Tacoma, WA 98466, http://www.apswood.org. ε(y)=strain distribution through beam depth (see Fig.A2.2)
D7199 − 20
the reinforcement type, reinforcement ratio, beam layup, and grade of the
ρ=tensile reinforcement ratio (%); cross-sectional area of
bumper lamination.
tensile reinforcement divided by cross-sectional area of beam
between the center of gravity of tensile reinforcement and the 4.4 Secondary Properties:
extreme compression fiber 4.4.1 Secondary properties such as bending about the y-y
ρ'=compressive reinforcement ratio (%); cross-sectional axis(F ),shearparalleltograin(F andF ),tensionparallel
by vx vy
area of compressive reinforcement divided by cross-sectional to grain (F), compression parallel to grain (F ), and compres-
t c
area of beam between the center of gravity of compressive sion perpendicular to grain (F ) shall be permitted to be
c'
reinforcement and the extreme tension fiber determined following methods described in Practice D3737.
σ(y)=stressdistributionthroughbeamdepth(seeFig.A2.2)
NOTE 5—Analysis has shown that with the level of FRP extreme fiber
tensile reinforcement typically envisioned (up to 3% GFRP or 1%
4. Modeling Requirements
CFRP), the maximum shear stress at the reinforced beam neutral axis is
very similar to that of an unreinforced rectangular section. In addition,
4.1 General:
under the same conditions, the shear stress at the FRP-wood interface is
4.1.1 Purpose for Modeling—Characteristic values for the
always significantly smaller than the shear stress at the reinforced beam
flexural properties about the x-x axis of horizontally-laminated
neutral axis.
reinforcedglulambeamsshallbeestablishedthroughtheuseof
5. Model Validation Testing Requirements
an analytical model. The establishment of flexural properties
using full-scale beam tests is outside the scope of this practice.
5.1 Test Method—Testsforflexuralstrengthandmodulusof
4.1.2 Mechanics-Based Models—Models used to develop
elasticity shall be conducted in accordance with Test Methods
new combinations and predict characteristic values shall be
D198 or D4761. If Test Methods D4761 is used, the load rate
able to predict accurately these values for a broad range of
shallbemodifiedtobeinaccordancewithTestMethodsD198.
combinations and validated by full-scale tests according to
Specimens shall be tested under dry-service conditions where
Section 5.
the moisture content of the wood, excluding non-wood
reinforcement, is 12 6 3 %. The temperature of the test
4.2 Minimum Model Inputs—Any numerical solution meth-
specimens shall not be less than 50°F (10°C) nor more than
odology shall be permitted for use, so long as it incorporates
90°F (32°C) at the time of the tests.
the nonlinearities in mechanical properties for wood and
reinforcement as specified in A2.1 and satisfies the conditions
5.2 Sampling Requirements—Mechanics-based models
of strain compatibility (A2.2), and equilibrium (A2.3). In
whichsatisfytherequirementssetforthinthisstandardshallbe
addition, the mechanics-based analysis shall account for vari-
validated through physical testing as shown in Tables 1 and 2.
ability of mechanical properties, volume effects, finger-joint
The sample size shall be large enough to provide the standard
effects, laminating effects, and stress concentrations at termi-
errorofthesamplelessthan10%ofthe5%LTLofMOR,but
nation of reinforcement in beams with partial length reinforce-
not less than 10 beams for each size/reinforcement ratio. Six
ment.
samplesetsshallbetestedusingaprimarywoodspecies(Table
1) equating to a minimum of 60 beams, and two sample sets
NOTE 2—These analysis input requirements are described in detail in
shall be tested for each additional wood species (Table 2)
Annex A2.
equating to a minimum of 20 beams.
4.3 Minimum Model Analyses:
4.3.1 Bending Strength—The model shall predict the lower
6. Analysis and Applicability of Test Results
5%tolerancelimit(LTL)formodulusofrupture(MOR )for
5%
6.1 FailureModes—Eachfailedspecimenshallbeinspected
the reinforced layup being analyzed. The model-predicted
to determine the failure mode(s). The location and type (end
bending strength characteristic values MOR shall include
5%
joint, lumber, shear, tension, compression, etc.) of observed
the volume effect. Beam MOR shall be based on gross (full
failures shall be documented and compared to the model.
width and depth) cross-sectional properties.
Lamination characteristics influencing failure shall be noted.
4.3.2 Bending Stiffness—The model shall predict the mean
modulus of elasticity (MOE) for the reinforced layup being
TABLE 1 Initial Qualification Using Primary Species: DF, SP, or
analyzed. Beam MOE shall be based on gross (full width and
SPF—Minimum Beam Test Matrix for Mechanics-Based Model
A,B
Validation
depth) cross-sectional properties.
4.3.3 Bumper Lamination—If a bumper lamination is to be Number of Beam Tests
Beam Size
C C C
Min Typical Max
used, the characteristic bending strength value MOR
BL5 %
corresponding to bumper lamination failure shall also be 5 ⁄8 in. by 12 in. by 21 ft 10 10 10
(130 mm by 305 mm by 6.40 m)
calculated and reported. In addition, the beam stiffness prop-
6 ⁄4 in. by 24 in. by 42 ft 10 10 10
ertiesbeforeandafterfailureofthebumperlaminationshallbe
(171 mm by 610 mm by 12.8 m)
calculated and reported. A
Allbeamsshallusethesamelayup,species,reinforcementtype,andwoodlam
thickness.
NOTE 3—See Appendix X1 for example calculations.
B
AlargersetshallberequirediftheStandardErrorisgreaterthan0.1×5%LTL.
NOTE4—Abumperlamination,ifused,willlikelyfailpriortoreaching
See Practice D2915 for determining the minimum sample size.
C
the ultimate capacity of the reinforced beam. In tests of GFRP-reinforced
See Table 3. The model shall only be considered valid for ρ within the tested
glulam with 1.1% to 3.3%, the bumper lam failure load was typically
minimum and maximum.
10–20% below the ultimate strength. This range will differ depending on
D7199 − 20
TABLE 2 Subsequent Qualification of Additional Species (DF, SP,
models shall be maintained through continuous process con-
SPF, or Hardwoods)—Minimum Beam Test Matrix for Mechanics-
trol. Strength and stiffness properties for each grade shall be
A,B
Based Model Validation
evaluated periodically or maintained through continuous pro-
Number of Beam Tests
Beam Size cess control to ensure that they are maintained over time.
C C C
Min Typical Max
7.2 Reinforcement Properties—The reinforcement charac-
5 ⁄8 in. by 18 in. by 32 ft 10 — 10
(130 mm by 457 mm by 9.75 m)
teristics used as inputs to predictive models shall be evaluated
A
periodically or maintained through continuous process control
Allbeamsshallusethesamelayup,species,reinforcementtype,andwoodlam
thickness.
to ensure that they are maintained over time.
B
AlargersetshallberequirediftheStandardErrorisgreaterthan0.1×5%LTL.
See Practice D2915 for determining a minimum sample size.
7.3 End Joint Strength—Lamination end joint strengths
C
See Table 3. The model shall only be considered valid for ρ within the tested
shall be subject to ongoing process control to maintain the
minimum and maximum.
required strengths.
7.4 Beam Tests—Full-scalebeamtestsshallbeconductedto
A
TABLE 3 Typical Reinforcement Ratios
verify the continued applicability of the model used for
Reinforcement Material
assigning characteristic values when the trend of the lumber
E-glass FRP Aramid FRP Carbon FRP Steel Plate
properties, reinforcement properties or end joint strengths,
MOE, ksi (GPa) 6 000 (41) 10 000 (69) 20 000 (138) 30 000 (207)
evaluated in 7.1 through 7.3, warrants such an evaluation.
B
Minimum ρ % 1 0.6 0.3 0.2
Typical ρ % 2 1.2 0.6 0.4
8. Report
Maximum ρ % 3 1.8 0.9 0.6
A
8.1 The report shall include the following:
The Reinforcement Ratios presented in this table represent typical values. The
manufacturer shall use any minimum, maximum, or typical value considered
8.1.1 Description of the sample(s), including species, lami-
appropriate, although the model shall only be valid within the range tested.
nation properties, layup(s), size(s), conditioning, location of
B
Tensile reinforcement ratio (%); cross-sectional area of tensile reinforcement
end joints, matched end joint strength, quality control
divided by cross-sectional area of beam above center of gravity of tensile
reinforcement.
requirements, etc.
8.1.2 Description of the test machine and setup, including
method and location of load application, test span or gauge
6.2 Mechanical Properties:
length, etc.
6.2.1 Modulus of Rupture—The predicted5%LTL using
8.1.3 Description of measurement methods for dimensions,
the mechanics-based model (5 % LTL ) shall be compared
model
load, deflections, moisture content, etc.
with the5%LTLcalculated from the test results (5 % LTL )
test
8.1.4 Rate of testing and the method of controlling the rate
for each of the eight cells in Tables 1 and 2. Conditions of
of load application.
model acceptance are as follows:
8.1.5 Equation(s) used to determine stresses and elastic
moduli.
5 % LTL 2 5 % LTL ⁄ 5 %LTL ,0.10
s d
| model test | model
8.1.6 Data for specimens, including: dimensions; maximum
for each of the 8 cells in Tables 1 and 2
load or stress, or both; moisture content; time to failure;
1/8Σ 5 % LTL 2 5 % LTL ⁄ 5 % LTL ,0.06
fs d g
model test model
description and location of failure; load versus deformation
for all 8 cells in Tables 1 and 2
curves, etc.
6.2.2 Modulus of Elasticity—Conditions for model accep-
8.1.7 Description of statistical analyses used to determine
tance include the mean MOE in the linear elastic range based
characteristic value(s).
on gross section dimensions as follows:
8.1.8 Identification and description of any model(s) used or
evaluated.
mean MOE 2 mean MOE ⁄ mean MOE ,0.10
s d
| model test | model
8.1.9 Details of any deviations from the recommended
for each of the 8 cells in Tables 1 and 2
procedures.
1/8Σf mean MOE 2 mean MOE ⁄ mean MOE g,0.06
s d
model test model
for all 8 cells in Tables 1 and 2
9. Keywords
7. Periodic Evaluation
9.1 bending;characteristicvalue;composites;flexural;flex-
7.1 Lumber Properties—The lumber characteristics used as ure; FRP; full-scale; glulam; laminated; layup; modulus; rein-
a basis for establishing grades and as inputs to predictive forcement; timber
D7199 − 20
ANNEXES
(Mandatory Information)
A1. PERFORMANCE-BASED DURABILITY REQUIREMENTS
A1.1 Reinforcement—The reinforcement shall maintain ad- times, clamping pressures, and ambient conditions shall reflect
equate strength and stiffness based on the anticipated end-use the key characteristics of the manufacturing equipment used in
conditionsoverthelifetimeofthestructure.Synergisticeffects the facility to be qualified and be clearly stated in the test
of the exposure conditions described in Table A1.1 shall be
report.
considered if appropriate for the end-use environment, using (3)Theresistancetoshearbycompressionloadingshallbe
the appropriate ASTM standards.
tested in the air dry (10 to 12% MC) and the wet (vacuum-
pressure soaked) conditions of Specification D2559. Shear
A1.1.1 Beams reinforced with FRPshall not be post-treated
block strength retention following the vacuum-pressure-soak
unless testing verifies that the required reinforced beam
cycle conditions shall be at least 75%.
strength and stiffness retentions can be achieved.
(4)In the case of FRP reinforcement, percent material
NOTE A1.1—Tests results have shown that post-treatment with CCA
failure includes both wood and reinforcement failure. Since
causes significant strength degradation of E-glass FRP reinforcement. It
material failure is predominantly in one lamination (the wood
shouldbenotedthatforotherreasons,thelaminatingindustryspecifically
recommendsagainstpost-treatmentofglulambeamswithanywaterborne lamina), the minimum acceptable limit shall be 60% material
treatments.
failure under dry conditions. In the case of steel or metallic
reinforcement,materialfailureisrestrictedtooneface,andthe
A1.1.2 After fabrication, reinforcement shall not be cut,
acceptable limit is reduced to 50%.
drilled, or otherwise damaged (including penetration by fas-
teners) unless proper mechanics-based engineering analyses
A1.2.2.2 Resistance to Delamination During Accelerated
are conducted to verify net section capacity, including effects
Exposure—Durability of wood-reinforcement bonds shall be
of stress-concentrations and potential for accelerated degrada-
evaluated according to: (a) resistance to delamination during
tion.
accelerated exposure to wetting and drying; and (b) resistance
to deformation under sustained static load as specified in the
A1.2 Bond—The bond shall provide strain compatibility
Specification D2559 with modifications to the delamination
between the wood and the reinforcement through the length of
test procedures as follows:
the reinforcement and be effective during the design life of the
(1)The reinforcement shall be applied to the Specification
structure.
D2559glulamtestbilletinawaythatbestreflectsthespecifics
A1.2.1 Wood-to-Wood Bond—Wood-to-wood bonds shall
of the real structural section to be qualified (either on top/
comply with requirements of ANSI A190.1 as well as Speci-
bottom or on side of the billet).
fication D2559.
(2)Specimens with maximum and minimum thickness of
reinforcement manufactured for the specific application being
A1.2.2 Wood-to-Reinforcement Bond:
qualified shall be used in the delamination test (see Fig.A1.2).
A1.2.2.1 Shear by Compression Loading—Wood-to-
Fig. A1.2(a) and (b) shall include multiple layers of FRP, as
reinforcementbondstrengthshallbeevaluatedforresistanceto
well as a flat-sawn bumper lams (with bark both facing and
shear by compression loading as specified in Specification
away from FRP), if this represents the intended end-use
D2559 with the following modifications:
application.
(1)When reinforcement sheets are too thin to allow proper
(3)Acceptable delamination for the wood-to-FRP bond
application of the compression load in the Test Method D905
lines shall be 8% maximum when measured in accordance
test apparatus, the FRP sheets shall be backed up by another
with the procedures described in Specification D2559.
wood layer (as shown in Fig. A1.1(b)).
(4)If preservative-treated wood is to be qualified, the
(2)The bonding protocol including wood and FRPsurface
delamination testing shall also be conducted using
preparation, primers, adhesive spread rates, open and closed
preservative-treated specimens. The long-term adhesive/
reinforcement/preservative interaction is outside the scope of
TABLE A1.1 Potential Reinforcement Exposure Conditions
this practice.
Condition Static Fatigue
A1.2.2.3 Creep—The following modifications to Specifica-
Water X X
tion D2559 test procedure for resistance to deformation under
Hot Water X X
sustained static load apply:
Salt Water X X
CaCO X (1)The internal layer of the test billet shall be fabricated
Diesel Fuel X
from the reinforcement material.
Freeze-Thaw X X
(2)Of the two testing conditions in the standard: elevated
Heat Aging X
relative humidity at ambient temperature versus elevated
UV Cycling X
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
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
of the standard as published by ASTM is to be considered the official document.
Designation: D7199 − 07 (Reapproved 2012) D7199 − 20
Standard Practice for
Establishing Characteristic Values for Reinforced Glued
Laminated Timber (Glulam) Beams Using Mechanics-Based
Models
This standard is issued under the fixed designation D7199; 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 mechanics-based requirements for calculating describes procedures for establishing the characteristic
values for the strength and stiffness of reinforced structural glued laminated timbers (glulam) manufactured in accordance with
applicable provisions of ANSI/AITC A190.1, subjected to quasi-static loadings. It addresses methods to obtain bending properties
parallel to grain, about the x-x axis (Freinforced structural glued-laminated timber (glulam) beams using mechanics-based models
and validated by full-scale beam tests. Glulam beams shall be manufactured in accordance with applicable provisions of ANSI
A190.1. and E ) for horizontally-laminated reinforced glulam beams. Secondary properties such as bending about the y-y axis
bx x
(F ), shear parallel to grain (F and F ), tension parallel to grain (F ), compression parallel to grain (F ), and compression
by vx vy t c
perpendicular to grain (F ') are beyond the scope of this practice. When determination of secondary properties is deemed
c
necessary, testing according to other applicable methods, such as Test Methods D143, D198 or analysis in accordance with Practice
D3737, is required to establish these secondary properties. Reinforced glulam beams subjected to axial loads are outside the scope
of this standard. This practice also provides minimum test requirements to validate the mechanics-based model.
1.2 TheThis practice also describes a minimum set of performance-based durability test requirements for reinforced glulams,
glulam beams, as specified in Annex A1. Additional durability test requirements shall be considered in accordance with the specific
end-use environment. Appendix X1 provides an example of a mechanics-based methodology that satisfies the requirements set
forth in this standard.practice.
1.3 This practice is limited to procedures for establishing flexural properties (modulus of rupture, MOR, and modulus of elasticity,
MOE) about the x-x axis of horizontally-laminated reinforced glulam beams.
1.4 The establishment of secondary properties, such as bending about the y-y axis, shear parallel to grain, tension parallel to grain,
compression parallel to grain, and compression perpendicular to grain, for the reinforced glulam beams are beyond the scope of
this practice.
NOTE 1—When the establishment of secondary properties is deemed necessary, testing according to other applicable methods, such as Test Methods D143
and D198 or analysis in accordance with Practice D3737, may be considered.
1.5 Reinforced glulam beams subjected to axial loads are outside the scope of this practice.
This practice is under the jurisdiction of ASTM Committee D07 on Wood and is the direct responsibility of Subcommittee D07.02 on Lumber and Engineered Wood
Products.
Current edition approved Oct. 1, 2012Aug. 1, 2020. Published October 2012August 2020. Originally approved in 2006. Last previous edition approved in 20072012 as
D7199 – 07.D7199 – 07 (2012). DOI: 10.1520/D7199-07R12.10.1520/D7199-20.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7199 − 20
1.6 Characteristic strength and elastic properties obtained using this standard may be used as a basis for developing design values.
However, the proper safety, serviceabilityProper safety, serviceability, and adjustment factors including duration of load, to be used
in design are outside the scope of this standard.practice.
1.7 This practice does not cover unbonded reinforcement, prestressed reinforcement, nor shear reinforcement.Evaluation of
unbonded, prestressed, and shear reinforcement is outside the scope of this practice.
1.8 The values stated in SIinch-pound units are to be regarded as standard. The mechanics based model may be values given in
parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. The
mechanics-based model shall be permitted to be developed using SI or in.-lbinch-pound units.
1.9 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.
1.10 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
D143 Test Methods for Small Clear Specimens of Timber
D198 Test Methods of Static Tests of Lumber in Structural Sizes
D905 Test Method for Strength Properties of Adhesive Bonds in Shear by Compression Loading
D1990 Practice for Establishing Allowable Properties for Visually-Graded Dimension Lumber from In-Grade Tests of Full-Size
Specimens
D2559 Specification for Adhesives for Bonded Structural Wood Products for Use Under Exterior Exposure Conditions
D2915 Practice for Sampling and Data-Analysis for Structural Wood and Wood-Based Products
D3039/D3039M Test Method for Tensile Properties of Polymer Matrix Composite Materials
D3410/D3410M Test Method for Compressive Properties of Polymer Matrix Composite Materials with Unsupported Gage
Section by Shear Loading
D3737 Practice for Establishing Allowable Properties for Structural Glued Laminated Timber (Glulam)
D4761 Test Methods for Mechanical Properties of Lumber and Wood-Based Structural Materials
D5124 Practice for Testing and Use of a Random Number Generator in Lumber and Wood Products Simulation
2.2 Other Standard:
ANSI/AITCANSI A190.1 Structural Glued Laminated Timber
3. Terminology
3.1 Definitions—Standard definitions of wood terms are given in Terminology D9 and standard definitions of structural glued
laminated timber terms are given in Practice D3737.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 bonded reinforcement—a reinforcing material that is continuously attached to a glulam beam through adhesive bonding.
3.2.2 bumper lamination—a wood lamination continuously bonded to the outer side of reinforcement.
3.2.3 compressioncompressive reinforcement—reinforcement placed on the compression side of a flexural member.
3.2.4 conventional wood lamstock—solid sawn wood laminations with a net thickness of 2 in. or less, graded either visually or
through mechanical means, finger-jointed and face-bonded to form a glulam.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’sstandard’s Document Summary page on the ASTM website.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.APA – The Engineered Wood
Association, 7011 South 19th Street, Tacoma, WA 98466, http://www.apswood.org.
D7199 − 20
3.2.5 development length—the length of the bond line along the axis of the beam required to develop the design tensile strength
of the reinforcement.
3.2.6 fiber-reinforced polymer (FRP)—anycomposite material consisting of at least two distinct components: reinforcing fibers and
a binder matrix (a polymer). The reinforcing fibers are permitted to be either synthetic (for example, glass), metallic, or natural
(for example, wood), and are permitted to be long and continuously-oriented, or short and randomly oriented. The binder matrix
is permitted to be either thermoplastic (for example, polypropylene or nylon) or thermosetting (for example, epoxy or vinyl-ester).
3.2.6.1 Discussion—
The reinforcing fibers may be either synthetic (for example, glass), metallic, or natural (for example, wood), and may be long and
continuously-oriented, or short and randomly oriented. The binder matrix may be either thermoplastic (for example, polypropylene
or nylon) or thermosetting (for example, epoxy or vinyl-ester).
3.2.7 laminating effect—an apparent increase of lumber lamination tensile strength because it is bonded to adjacent laminations
within a glulam beam. This apparent increase may be attributed to a redirection of stresses around knots and grain deviations
through adjacent laminations.
3.2.7.1 Discussion—
This apparent increase may be attributed to a redirection of stresses around knots and grain deviations through adjacent
laminations.
3.2.8 partial length reinforcement—reinforcement that is terminated within the length of the timber.glulam.
3.2.9 reinforcement—any lamination or material that is not a conventional lamstock whose wood lamstock and having a mean
longitudinal ultimate strength exceeds 20 ksi for tension and compression, and whose tensile and compressive strength greater than
20 ksi (138 MPa) and a mean tension and compression MOE exceeds 3000 ksi, when placed into a glulam timber. Acceptable
reinforcing materials include but are not restricted to: fiber-reinforced polymer (FRP) plates and bars, metallic plates and bars,
FRP-reinforced laminated veneer lumber (LVL), FRP-reinforced parallel strand lumber (PSL).greater than 3000 ksi (20.7 GPa).
3.2.9.1 Discussion—
Examples of acceptable reinforcing materials include fiber-reinforced polymer (FRP) plates and bars, metallic plates and bars,
FRP-reinforced laminated veneer lumber (LVL), and FRP-reinforced parallel strand lumber (PSL).
3.2.10 shear reinforcement—reinforcement intended to increase the shear strength of the beam. This standard does not cover shear
reinforcement.
3.2.10 tensiontensile reinforcement—reinforcement placed on the tension side of a flexural member.
3.3 Symbols: Symbols:
Arm = moment arm, distance between compressioncompressive and tensiontensile force couple applied to beam cross-section
b = beam width
C = total internal compressioncompressive force within the beam cross-section (see Fig. 2A2.2)
CFRP = carbon fiber reinforced polymer
d = beam depth
E = long-span flatwise-bending modulus of elasticity for wood lamstock (Test Methods D4761; also see Fig. 1A2.1)
F = allowable bending stress parallel to grain
b
F = internal horizontal force on the beam cross-section (see Eq 2A2.2)
x
GFRP = Glass fiber-reinforced polymer
LEL = lower exclusion limit (point estimate with 50 % confidence, includes volume factor)
LTL = lower tolerance limit (typically calculated with 75 % confidence)with 75 % confidence
M = external moment applied to the beam cross-section
applied
M = internal moment on the beam cross-section
internal
MC = moisture content (%)
MOE = modulus of elasticity
MOR = modulus of rupture
MOR = 5 % one-sided lower tolerance limit for modulus of rupture, including the volume factor
5%5 %
D7199 − 20
MOR = 5 % one-sided lower tolerance limit for modulus of rupture corresponding to failure of the bumper lamination,
BL5%BL5 %
including the volume factor
m*E = downward slope of bilinear compression stress-strain curve for wood lamstock (see Fig. 1A2.1)
N.A. = neutral axis
T = total internal tensiontensile force within the beam cross-section (see Fig. 2A2.2)
UCS = ultimate compressive stress parallel to grain
UTS = ultimate tensile stress parallel to grain
Y = distance from extreme compression fiber to neutral axis (see Fig. 2A2.2)
y = distance from extreme compression fiber to point of interest on beam cross-section (see Fig. 2A2.2)
ε = strain at extreme compression fiber of beam cross-section (see Fig. 2A2.2)
c
ε = compression = compressive strain at lamstock failure (see Fig. 1A2.1)
cult
ε = compression = compressive yield strain at lamstock UCS (see Fig. 1A2.1)
cy
ε = tensile strain at lamstock failure (see Fig. 1A2.1)
tult
ε(y) = strain distribution through beam depth (see Fig. 2A2.2)
ρ = tensionρ = tensile reinforcement ratio (%); cross-sectional area of tensiontensile reinforcement divided by cross-sectional
area of beam between the c.g. of tension center of gravity of tensile reinforcement and the extreme compression fiber
ρ' = compressionρ' = compressive reinforcement ratio (%); cross-sectional area of compression compressive reinforcement
divided by cross-sectional area of beam between the c.g. of compression center of gravity of compressive reinforcement and the
extreme tension fiber
σ(y) = stress distribution through beam depth (see Fig. 2A2.2)
4. Requirements for Mechanics-Based Analysis Methodology Modeling Requirements
NOTE 1—At a minimum, the mechanics-based analysis shall account for: (1) Stress-strain relationships for wood laminations and reinforcement; (2) Strain
compatibility; (3) Equilibrium; (4) Variability of mechanical properties; (5) Volume effects; (6) Finger-joint effects; (7) Laminating effects; and (8) Stress
concentrations at termination of reinforcement in beams with partial length reinforcement. In addition to the above factors, characteristic values developed
using the mechanics-based model need to be further adjusted to address end-use conditions including moisture effects, duration of load, preservative
treatment, temperature, fire, and environmental effects. The development and application of these additional factors are outside the scope of this practice.
Annex A1 addresses the evaluation of durability effects. The minimum output requirements for the analysis are mean MOE (based on gross section) and
5% LTL MOR with 75 % confidence (based on gross section), both at 12 % MC. These analysis requirements are described below.
4.1 Stress-strain Relationships: General:
4.1.1 Conventional Wood Lamstock: Purpose for Modeling—
4.1.1.1 The stress-strain relationship shall be established through in-grade testing following Test Methods D198 or Test Methods
D4761, or other established relationships as long as the resulting model meets the criteria established in Section 5. Test lamstock
shall be sampled in sufficient quantity from enough sources to insure that the test results are representative of the lamstock
population that will be used in the fabrication of the beams. Follow-up testing shall be performed annually in order to track changes
in lamstock properties over time, so that the layup designs may be adjusted accordingly.Characteristic values for the flexural
properties about the x-x axis of horizontally-laminated reinforced glulam beams shall be established through the use of an
analytical model. The establishment of flexural properties using full-scale beam tests is outside the scope of this practice.
4.1.1.2 The stress-strain relationship shall be linear in tension. The stress-strain relationship shall be nonlinear in compression if
compression is the governing failure mode. In this case, a bilinear approximation is acceptable, and shall be used throughout this
standard (see Fig. 1). In the bilinear model both tension and compression MOE shall be permitted to be approximated by using
the long-span flatwise-bending MOE obtained using Test Methods D4761. In Fig. 1, m*E is the downward slope of the
compression stress-strain curve, defined as the best-fit downward line through the point (UCS, ε ) on the compression stress-strain
cy
curve. The downward best-fit line shall be permitted to be terminated at the point where the ultimate compressive strain ε is
cu
approximately 1 %.
4.1.2 Reinforcement: Mechanics-Based Models—
4.1.2.1 The stress-strain relationship shall be established through material-level testing in accordance with Test Method
D3039/D3039M and D3410/D3410M.Models used to develop new combinations and predict characteristic values shall be able to
predict accurately these values for a broad range of combinations and validated by full-scale tests according to Section 5.
4.1.2.2 Nonlinearities in the stress-strain relationship shall be included in the analysis, if present.
4.1.2.3 Acceptable stress-strain models for unidirectional E-glass FRP (GFRP), Aramid, or Carbon FRP (CFRP) in tension are
D7199 − 20
linear-elastic. Acceptable models for hybrid E-glass/Carbon composites in tension are linear or bilinear. Acceptable models for
mild steel reinforcement are elastic-plastic. Similar models may also apply in compression.
4.2 Strain Compatibility:
4.2.1 Fig. 2 shows the cross section of a beam with a linear strain and bilinear stress distribution, with the neutral axis a distance
Y below the top of the beam. Using the extreme compression fiber as the origin, the strain distribution for a given applied moment
(M ) is defined by the equation:
applied
ε~y! 5 ε 2 ε *~y/Y! (1)
c c
4.2 Equilibrium: Minimum Model Inputs—
4.3.1 In order to maintain equilibrium, the cross-section shall satisfy the conditions of horizontal equilibrium (Eq 2), and the
internal moment (M ) shall equal the external moment applied to that cross section (M ) (Eq 3). See Fig. 2 as an example
internal applied
of strain compatibility and equilibrium:
F 5 0⇒* σ y dA 5 0 (2)
~ !
( x
depth
M 5 M 5 C~or T!*Arm5* 2 y*σ~y!*dA (3)
applied internal
depth
Any numerical solution methodology shall be permitted for use, so long as it incorporates the nonlinearities in mechanical
properties for wood and reinforcement as specified in A2.1 and satisfies the conditions of strain compatibility (A2.2), and
equilibrium (A2.3). In addition, the mechanics-based analysis shall account for variability of mechanical properties, volume
effects, finger-joint effects, laminating effects, and stress concentrations at termination of reinforcement in beams with partial
length reinforcement.
NOTE 2—These analysis input requirements are described in detail in Annex A2.
4.4 Variability of Mechanical Properties:
4.4.1 The model shall properly account for the variability of the mechanical properties of the wood lamstock and the FRP
reinforcement. This includes variability of individual properties and correlations among those properties as appropriate. The
mechanics-based analysis shall address statistical properties for and correlations between Ultimate Tensile Stress (UTS), Ultimate
Compressive Stress (UCS) and long-span flatwise-bending modulus of elasticity (E). One example of how this may be achieved
is provided in Appendix X1.
4.4.2 These correlation values are obtained from test data. Test lamstock shall be sampled in sufficient quantity, from enough
sources to insure that the test results are representative of the lamstock population that will be used in the fabrication of the beams.
Follow-up testing shall be performed annually in order to track changes in lamstock properties over time, so that the layup designs
may be adjusted accordingly.
4.5 Volume Effects:
4.5.1 The model shall properly account for changes in beam strength properties as affected by beam size. In conventional glulam,
this is achieved by using a volume factor C , which was derived from laboratory test data. With adequate reinforcement, glulams
v
can achieve a reduction or even elimination of volume effects. The model shall properly account for this phenomenon. One possible
approach to address the volume effect is described in Appendix X1.
4.6 Finger-Joint Effects:
4.6.1 Finger joints affect the mechanical properties of lamstock used in glulams. The model shall account for these effects on both
the mean and variability of the beam mechanical properties. One example of how this may be achieved is provided in Appendix
X1.
4.7 Laminating Effects:
D7199 − 20
4.7.1 The laminating effects may be predicted by the model or else developed outside the model (and applied in the model) using
an empirical, numerical or analytical approach. One way to achieve this for a beam subjected to 4-point bending is described in
Appendix X1.
4.8 Stress Concentrations at Termination of Reinforcement in Beams with Partial Length Reinforcement:
4.8.1 Beams with partial length reinforcement have stress concentrations near the ends of the reinforcement. These stress
concentrations are in the form of tension or compression stresses parallel to grain, combined with peeling stresses perpendicular
to grain. The model shall have the ability to account for the effects of these stress concentrations if partial length reinforcement
will be used.
4.3 Mechanical Properties Predicted by Model: Minimum Model Analyses:
4.9.1 The model shall at a minimum predict the following properties, including the effects of a bumper lamination if one is used,
which are the basis for design values.
4.3.1 Bending Strength: Strength—
4.9.2.1 The bending strength calculated by the model assumes adequate bond development length is provided for the
reinforcement. The model shall predict the lower 5 % tolerance limit for modulus of rupture (MOR ) for the reinforced layup
5%
being analyzed. Beam MOR shall be based on gross (full width and depth) cross section properties:
6*M
max
MOR 5 (4)
b*d
Where M is the maximum moment applied to the beam, and b and d are respectively the full width and depth of the beam
max
cross-section. The transformed section properties shall not be used.The model shall predict the lower 5 % tolerance limit (LTL)
for modulus of rupture (MOR ) for the reinforced layup being analyzed. The model-predicted bending strength characteristic
5 %
values MOR shall include the volume effect. Beam MOR shall be based on gross (full width and depth) cross-sectional
5 %
properties.
4.9.2.2 If a bumper lamination is used, an additional characteristic bending strength value MOR corresponding to bumper
BL5%
lamination failure shall also be reported. It should be noted that the model-predicted bending strength characteristic values MOR
5%
and MOR shall include the volume effect, so that the volume factor will not be applied separately.
BL5%
4.3.2 Bending Stiffness—The model shall predict the mean modulus of elasticity (MOE) for the reinforced layup being analyzed.
Beam MOE shall be based on gross (full width and depth) cross-sectional properties.
4.3.3 Bending Stiffness: Bumper Lamination—
4.9.3.1 The model shall predict the mean modulus of elasticity (MOE) for the reinforced layup being analyzed. MOE shall be
based on gross (full width and depth) cross-section properties. If a bumper lamination is present, the model shall predict the beam
stiffness properties before and after failure of the bumper lamination.If a bumper lamination is to be used, the characteristic
bending strength value MOR corresponding to bumper lamination failure shall also be calculated and reported. In addition,
BL5 %
the beam stiffness properties before and after failure of the bumper lamination shall be calculated and reported.
4.9.3.2 If a bumper lamination is used, the model shall be able to predict failure of the bumper lamination, as well as its
contribution to beam strength and stiffness. The modeling approach described in Appendix X1 is an example of how to accomplish
this.
NOTE 3—See Appendix X1 for example calculations.
NOTE 4—A bumper lamination, if used, will likely fail prior to reaching the ultimate capacity of the reinforced beam. In tests of GFRP-reinforced glulam
with 1.1 % to 3.3 %, the bumper lam failure load was typically 10–20 % below the ultimate strength. This range will differ depending on the reinforcement
type, reinforcement ratio, beam layup, and grade of the bumper lamination.
NOTE 2—A bumper lamination, if used, will likely fail prior to reaching the ultimate capacity of the reinforced beam. In tests of GFRP-reinforced glulam
with 1.1 % to 3.3 %, the bumper lam failure load was typically 10-20 % below the ultimate strength. This range will differ depending on the reinforcement
type, reinforcement ratio, beam layup, and grade of the bumper lamination.
D7199 − 20
TABLE 1 Initial Qualification Using Primary Species: DF, SP or
SPF—Minimum Beam Test Matrix for Mechanics-Based Model
A,B
Validation
Reinforcement Ratio ρ %
Beam Size
C C C
Min Typical Max
5 ⁄8 in. by 12 in. by 21 ft 10 10 10
6 ⁄4 in. by 24 in. by 42 ft. 10 10 10
TABLE 1 Initial Qualification Using Primary Species: DF, SP, or
SPF—Minimum Beam Test Matrix for Mechanics-Based Model
A,B
Validation
Number of Beam Tests
Beam Size
C C C
Min Typical Max
5 ⁄8 in. by 12 in. by 21 ft 10 10 10
(130 mm by 305 mm by 6.40 m)
6 ⁄4 in. by 24 in. by 42 ft 10 10 10
(171 mm by 610 mm by 12.8 m)
A
All beams shall use the same layup, species, reinforcement type, and wood lam
thickness.
B
A A larger set mayshall be required in order to keep if the Standard Error less is
greater than 0.1 * (5%LEL). × 5 % LTL. See Practice D2915, Section 3.4.3.2 for
determining athe minimum sample size.
C
See Table 3. The model willshall only be considered valid for ρ within the tested
minimum and maximum.
TABLE 2 Subsequent Qualification of Additional Species (DF, SP,
SPF or hardwoods)—Minimum Beam Test Matrix for Mechanics-
A,B
Based Model Validation
Reinforcement Ratio ρ %
Beam Size
C C C
Min Typical Max
5 ⁄8 in. by 18 in. by 32 ft. 10 — 10
TABLE 2 Subsequent Qualification of Additional Species (DF, SP,
SPF, or Hardwoods)—Minimum Beam Test Matrix for Mechanics-
A,B
Based Model Validation
Number of Beam Tests
Beam Size
C C C
Min Typical Max
5 ⁄8 in. by 18 in. by 32 ft 10 — 10
(130 mm by 457 mm by 9.75 m)
A
All beams shall use the same layup, species, reinforcement type, and wood lam
thickness.
B
A A larger set mayshall be required in order to keep if the Standard Error less is
greater than 0.1 * (5%LEL). × 5 % LTL. See Practice D2915 Section 3.4.3.2 for
determining a minimum sample size.
C
See Table 3. The model willshall only be considered valid for ρ within the tested
minimum and maximum.
A
TABLE 3 Typical Reinforcement Ratios
Reinforcement Material
E-glass FRP Aramid FRP Carbon FRP Steel Plate
MOE (ksi) 6 000 10 000 20 000 30 000
MOE, ksi (GPa) 6 000 (41) 10 000 (69) 20 000 (138) 30 000 (207)
B
Minimum ρ % 1 0.6 0.3 0.2
Typical ρ % 2 1.2 0.6 0.4
Maximum ρ % 3 1.8 0.9 0.6
A
The The Reinforcement Ratios presented in this table represent typical values.
The manufacturer mayshall use any minimum, maximum, or typical value consid-
ered appropriate, although the model willshall only be valid within the range tested.
B
ρ = Tension Tensile reinforcement ratio (%); cross-sectional area of tensionten-
sile reinforcement divided by cross-sectional area of beam above c.g. of tension
center of gravity of tensile reinforcement.
4.4 Secondary Properties:
D7199 − 20
4.10.1 Secondary properties such as bending about the y-y axis (F ), shear parallel to grain (F and F ), tension parallel to grain
by vx vy
(F ), compression parallel to grain (F ), and compression perpendicular to grain (F ) shall be determined following methods
t c c'
described in Practice D3737.
4.4.1 Analysis has shown that with the level of FRPSecondary properties such as bending about the y-y axis (F extreme fiber
by
tension reinforcement typically envisioned (up to 3 % GFRP), shear parallel to grain (F or 1 %and F CFRP), the maximum
vx vy
shear stress at the reinforced beam neutral axis is very similar to that of), tension parallel to grain (F an unreinforced rectangular
t
section. In), compression parallel to grain (F addition, under the same conditions, the), and compression perpendicular to grain
c
(F shear stress at the FRP-wood interface is always significantly smaller than) shall be permitted to be determined following
c'
methods described in Practice D3737the shear stress at the reinforced beam neutral axis.
NOTE 5—Analysis has shown that with the level of FRP extreme fiber tensile reinforcement typically envisioned (up to 3 % GFRP or 1 % CFRP), the
maximum shear stress at the reinforced beam neutral axis is very similar to that of an unreinforced rectangular section. In addition, under the same
conditions, the shear stress at the FRP-wood interface is always significantly smaller than the shear stress at the reinforced beam neutral axis.
4.11 Numerical Solution Methodology:
4.11.1 Any numerical solution methodology shall be permitted for use, so long as it incorporates the nonlinearities in mechanical
properties for wood and FRP as specified in section 4.1, and satisfies the conditions of strain compatibility (section 4.2), and
equilibrium (section 4.3).
5. Model Validation Testing Requirements
5.1 Test Method—Tests for flexural strength and modulus of elasticity shall be conducted in accordance with Test Methods D198
or D4761. If Test Methods D4761 is used, the load rate shall be modified to be in accordance with Test Methods D198. Specimens
shall be tested under dry-service conditions where the moisture content of the wood, excluding non-wood reinforcement, is 12 6
3 %. The temperature of the test specimens shall not be less than 50°F (10°C) nor more than 90°F (32°C) at the time of the tests.
5.2 Sampling Requirements—Mechanics-based models which satisfy the requirements set forth in this standard shall be validated
through physical testing as shown in Tables 1 and 2. The sample size shall be large enough to provide the standard error of the
sample less than 10 % of the 5 % LTL of MOR, but not less than 10 beams for each size/reinforcement ratio. Six sample sets shall
be tested using a primary wood species (Table 1) equating to a minimum of 60 beams, and two sample sets shall be tested for each
additional wood species (Table 2) equating to a minimum of 20 beams.
6. Standard Methodology for Validating Mechanics-Based Models which Satisfy the Requirements Set Forth in This
Standard Analysis and Applicability of Test Results
6.1 Failure Modes—Mechanics-based models which satisfy the requirements set forth in this standard shall be validated through
physical testing as shown inEach failed specimen shall be inspected to determine the failure mode(s). The Tables 1-3. Being
mechanics-based, the model shall be validated using 60 beams for one primary wood species (location and type (end joint, lumber,
shear, tension, compression, etc.) of observed failures shall be documented Table 1), and 20 beams for each additional wood
species (and compared to Table 2). All beams in Table 3 shall utilize the same wood layup, and the same type of reinforcement.the
model. Lamination characteristics influencing failure shall be noted.
Typical solutions for the nonlinear set The boldface numbers in parentheses refer to a list of Eq 1-3 may be Newton-Raphson or other iterative techniques.references
at the end of this standard.
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6.2 The predicted 5% LEL using the mechanics-based model (5% LEL ) shall be compared with the 5% LEL calculated from
model
the test results (5% LEL ) for each of the eight cells in Tables 1 and 2. Conditions of model acceptance are as follows:Mechanical
test
Properties:
|(5% LEL – 5% LEL )| / 5% LEL < 0.10
model test model
for each of the 8 cells in Tables 1 and 2
⁄8 Σ (5% LEL – 5% LEL ) / 5% LEL < 0.06
model test model
for all 8 cells in Tables 1 and 2
6.2.1 Modulus of Rupture—The predicted 5 % LTL using the mechanics-based model (5 % LTL ) shall be compared with the
model
5 % LTL calculated from the test results (5 % LTL ) for each of the eight cells in Tables 1 and 2. Conditions of model acceptance
test
are as follows:
5 % LTL 2 5 % LTL ⁄ 5 %LTL ,0.10
s d
| model test | model
for each of the 8 cells in Tables 1 and 2
1/8 Σf 5 % LTL 2 5 % LTL ⁄ 5 % LTL g,0.06
s d
model test model
for all 8 cells in Tables 1 and 2
6.2.2 Modulus of Elasticity—Conditions for model acceptance include the mean MOE in the linear elastic range based on gross
section dimensions as follows:
mean MOE 2 mean MOE ⁄ mean MOE ,0.10
s d
| model test | model
for each of the 8 cells in Tables 1 and 2
1/8Σfsmean MOE 2 mean MOE d ⁄ mean MOE g,0.06
model test model
for all 8 cells in Tables 1 and 2
5.3 Similarly, conditions for model acceptance include the mean MOE in the linear elastic range based on gross section
dimensions as follows:
|(mean MOE – mean MOE )| / mean MOE < 0.10
model test model
for each of the 8 cells in Tables 1 and 2
⁄8 Σ (mean MOE – mean MOE ) / mean MOE < 0.06
model test model
for all 8 cells in Tables 1 and 2
5.4 It is important to stress that a test sample size larger than indicated in Tables 1 and 2 shall be considered in order to keep the
Standard Error less than 0.1 * (5 % LEL). Section 3.4.3.2 of Practice D2915 shall be used for determining an adequate minimum
test sample size.
5.5 In addition to the 5 % LEL predictions, the predominant mode of failure shall be identified by the model for each reinforcement
level tested, and this mode of failure shall compare with the mode of failure observed in the laboratory testing program. For the
beam confirmation testing the characteristics of the wood laminations (for example, finger-joint spacing, lumber grade etc.) need
to be consistent with the model.
5.6 In addition to Test Methods D198 test reporting requirements, the report shall include: (1) details of the layups tested including
grades, distribution of finger-joint spacings and strengths, reinforcement location, strength and stiffness, (2) failure modes
(predicted and lab test results), (3) load to failure (predicted and lab test results), (4) load-deflection curves (predicted and lab test
results), (5) 5 % LEL analysis (predicted and lab test results as described above).
7. Periodic Evaluation
7.1 Lumber Properties—The lumber characteristics used as a basis for establishing grades and as inputs to predictive models shall
be maintained through continuous process control. Strength and stiffness properties for each grade shall be evaluated periodically
or maintained through continuous process control to ensure that they are maintained over time.
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7.2 Reinforcement Properties—The reinforcement characteristics used as inputs to predictive models shall be evaluated
periodically or maintained through continuous process control to ensure that they are maintained over time.
7.3 End Joint Strength—Lamination end joint strengths shall be subject to ongoing process control to maintain the required
strengths.
7.4 Beam Tests—Full-scale beam tests shall be conducted to verify the continued applicability of the model used for assigning
characteristic values when the trend of the lumber properties, reinforcement properties or end joint strengths, evaluated in 7.1
through 7.3, warrants such an evaluation.
8. Report
8.1 The report shall include the following:
8.1.1 Description of the sample(s), including species, lamination properties, layup(s), size(s), conditioning, location of end joints,
matched end joint strength, quality control requirements, etc.
8.1.2 Description of the test machine and setup, including method and location of load application, test span or gauge length, etc.
8.1.3 Description of measurement methods for dimensions, load, deflections, moisture content, etc.
8.1.4 Rate of testing and the method of controlling the rate of load application.
8.1.5 Equation(s) used to determine stresses and elastic moduli.
8.1.6 Data for specimens, including: dimensions; maximum load or stress, or both; moisture content; time to failure; description
and location of failure; load versus deformation curves, etc.
8.1.7 Description of statistical analyses used to determine characteristic value(s).
8.1.8 Identification and description of any model(s) used or evaluated.
8.1.9 Details of any deviations from the recommended procedures.
9. Keywords
9.1 bending; characteristic value; composites; flexural; flexure; FRP; full-scale; glulam; laminated; layup; modulus; reinforce-
ment; timber
ANNEXANNEXES
(Mandatory Information)
A1. PERFORMANCE-BASED DURABILITY REQUIREMENTS
A1.1 Reinforcement—Reinforcement—The reinforcement shall maintain adequate strength and stiffness based on the anticipated
end-use conditions over the lifetime of the structure. Synergistic effects of the exposure conditions described in Table A1.1 shall
be considered if appropriate for the end-use environment, using the appropriate ASTM standards.
A1.1.1 Beams reinforced with FRP shall not be post-treated unless testing verifies that the required FRP reinforced beam strength
and stiffness retentions can be achieved. Tests results have shown that post-treatment with CCA causes significant strength
degradation of E-glass FRP reinforcement. It should be noted that for other reasons, the laminating industry specifically
recommends against post-treatment of glulam beams with any waterborne treatments.
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TABLE A1.1 Potential Reinforcement Exposure Conditions
Condition Static Fatigue
Water X X
Hot Water X X
Salt water X X
Salt Water X X
CaCO X
Diesel Fuel X
Freeze-thaw X X
Freeze-Thaw X X
Heat Aging X
UV Cycling X X
Fire X
Wood Preservatives X X
Sustained Loading X X
NOTE A1.1—Tests results have shown that post-treatment with CCA causes significant strength degradation of E-glass FRP reinforcement. It should be
noted that for other reasons, the laminating industry specifically recommends against post-treatment of glulam beams with any waterborne treatments.
A1.1.2 After fabrication, reinforcement shall not be cut, drilled, or otherwise damaged (including penetration by fasteners) unless
proper mechanics-based engineering analyses are conducted to verify net section capacity, including effects of stress-
concentrations and potential for accelerated degradation.
A1.2 Bond—The bond is to shall provide strain compatibility between the wood and the reinforcement through the length of the
reinforcement and be effective during the design life of the structure.
A1.2.1 Wood-to-Wood Bond—Wood-to-wood bonds shall comply with requirements of ANSI/AITCANSI A190.1 as well as
Specification D2559.
A1.2.2 Wood-to-Reinforcement Bond:
A1.2.2.1 Shear by Compression Loading—Wood-to-reinforcement bond strength shall be evaluated for resistance to shear by
compression loading as specified in Specification D2559 with the following modifications:
(1) When reinforcement sheets are too thin to allow proper application of the compression load in the Test Method D905 test
apparatus, the FRP sheets shall be backed up by another wood layer (as shown in Fig. A1.1(b)).
FIG. A1.1 Block Shear Specimens for Modified Specification D2559 Test
(a) Regular Wood-Wood Specimen; (b) Modified Reinforcement-Wood Specimen—for Thin Reinforcement Sheets; (c) Modified
Reinforcement-Wood Specimen for Thick Reinforcement Sheets
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(2) The bonding protocol including wood and FRP surface preparation, primers, adhesive spread rates, open and closed times,
clamping pressures, and ambient conditions shall be reflect the key characteristics of the manufacturing equipment used in the
facility to be qualified and be clearly stated in the test report.
(3) The resistance to shear by compression loading shall be tested in the air dry (10 to 12 % MC) and the wet (vacuum-pressure
soaked) conditions of Specification D2559. Shear block strength retention following the vacuum-pressure-soak cycle conditions
shall be at least 75 %.
(4) In the case of FRP reinforcement, percent material failure includes both wood and reinforcement failure. Since material
failure is predominantly in one facelamination (the wood face),lamina), the minimum acceptable limit shall be 60 % material
failure under dry conditions. In the case of steel or metallic reinforcement, material failure is restricted to one face, and the
acceptable limit is reduced to 50 %.
(5) In addition, durability of wood-reinforcement bonds shall be evaluated according to: (1) resistance to delamination during
accelerated exposure to wetting and drying; and (2) resistance to deformation under sustained static load as specified in the
Specification D2559 with modifications to the delamination test procedures as follows:
A1.2.2.2 Accelerated Hygrothermal Cycling: Resistance to Delamination During Accelerated Exposure—Durability of wood-
reinforcement bonds shall be evaluated according to: (a) resistance to delamination during accelerated exposure to wetting and
drying; and (b) resistance to deformation under sustained static load as specified in the Specification D2559 with modifications to
the delamination test procedures as follows:
(1) The reinforcement shall be applied to the Specification D2559 glulam test billet in a way that best reflects the specifics of
the real structural section to be qualified (either on top/bottom or on side of the billet).
(2) Specimens with maximum and minimum thickness of reinforcement manufactured for the specific application being
qualified shall be used in the delamination test (see Fig. A1.2). Fig. A1.2(a) and (b) shall include multiple layers of FRP, as well
as a flat-sawn bumper lams (with bark both facing and away from FRP), if this represents the intended end-use application.
(3) Since the FRP behaves more like a hardwood surface than a softwood surface, acceptable delamination limits Acceptable
delamination for the wood-to-FRP bond lines are 8 % as opposed to 5 % for the softwood-softwood bond lines.shall be 8 %
maximum when measured in accordance with the procedures described in Specification D2559.
(4) If preservative-treated wood is used, the to be qualified, the delamination testing shall also be conducted using
preservative-treated specimens, keeping the same standards for delamination as for untreated specimens. Note that the specimens.
The long-term adhesive/reinforcement/preservative interaction may require further study.is outside the scope of this practice.
A1.2.2.3 Creep—The following modifications to Specification D2559 test procedure for resistance to deformation under sustained
static load apply:
(1) The internal layer of the test billet shall be fabricated from the reinforcement material.
(2) Of the two testing conditions in the standard: elevated relative humidity at ambient temperature versus elevated temperature
at ambient humidity, the second regime shall be used due to relatively low glass transition temperatures of some adhesives used
for wood-reinforcement bonding.
A1.2.3 Reinforcement-to-Reinforcement Bond—Reinforcement-to-reinforcement mean bond strength shall equal to or exceed the
mean strength of the wood-to-wood bond for the species of wood used in the beam, under both dry and wet conditions, tested using
the compression shear test from Test Method D905.
FIG. A1.2 Delamination Specimens for Modified Specification D2559 Test
(a) Maximum Thickness of the Reinforcement Layer(s); (b) Minimum Thickness of the Reinforcement Layer(s)
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A1.3 Fatigue:
A1.3.1 When fatigue is a design consideration, fatigue testing at the coupon level shall be conducted to insureensure proper
performance of the FRP under fatigue loading under the specific end-use environment. Full-scale fatigue testing is required when
partial-length reinforcement is used to evaluate the effectiveness of reinforcement end-confinement detail. Unconfined,
partial-length reinforcement shall not be permitted in situations where fatigue loading exists.
A1.3.2 If the reinforcement increases the MOR of the beam by more than 75 % relative to the strength of the unreinforced
5 %
beam, full-scale reinforced beam fatigue testing shall be conducted if fatigue is a design consideration. Under these conditions
flexural compression, flexural tension, and flexural shear fatigue failures in the wood laminations have been observed in reinforced
glulam beams.
NOTE A1.2—Under these conditions, flexural compression, flexural tension, and flexural shear fatigue failures in
...