Strengthening of Wood Beams Using FRP Composites

H. J. Dagher, Ph.D., P.E.1 and R. Lindyberg. M.S., P.E.2

ABSTRACTGlued laminated timber beams (glulam) can be reinforced on the tension side with Fiber-Reinforced-Polymers (FRP) to increase their strength, stiffness and ductility. FRP-glulams offer a cost-effective alternative for short-span girder bridges (< 60ft). With aslittle as 3% E-glass FRP tension reinforcement ratio (GFRP), the allowable bendingstrength of wood laminated beams can be increased by as much as 100%. GFRPreinforcement can therefore reduce wood requirements and under some conditions reducematerial costs. Current barriers to the deployment of the technology are: (1) lack ofpublished data on the strength and durability of GFRP-reinforced glulam girders forbridge applications, (2) the absence of AASHTO Specifications for reinforced glulams.

Under a 5-year contract by the FHWA executed in December 1999, the University ofMaine is developing Guide Specifications for reinforced glulams for consideration byAASHTO. The provisions will be divided into two parts: (1) design, and (2) materialspecifications. The material specifications will be performance-based and will beapplicable for a wide range of wood species, grades and FRP types. This paper providesan overview of the project results to date. The focus is on short-term ultimate strengthand static design of reinforced glulam girders. In addition, the paper provides a list ofstandard test methods being considered to evaluate the short- and long-term performanceof FRP-glulams in bridge applications.

Keywords: Timber, bridges, glulam, Fiber-Reinforced-Polymers, Design

INTRODUCTIONAdvanced Wood Composites (AWC) refer to a new class of materials resulting from

the combination of wood with Fiber-Reinforced Polymers (FRP). These materials couplethe advantages of wood which include high performance/cost and strength/weight ratios,with the advantages of FRP which include high strength and stiffness, and versatility.

FRPs are a versatile class of materials consisting of (1) synthetic fibers includingglass, carbon, graphite and aramid in forms such as continuous rovings, chopped strands,mats, woven rovings or textiles, and (2) a thermoset or thermoplastic polymer matrixwhich serves to bind the fibers together, transfer loads to the fibers, and protect themagainst environmental attack.

1 Director, Advanced Engineered Wood Composites Center, 5793 AEWC Building, Room 104, University of Maine,

Orono, ME 04469-5793. Tel (207) 581-2138 Fax (207) 581-2074 E-mail: hd@umit.maine.edu2 Research Engineer, Advanced Engineered Wood Composites Center, AEWC Building, University of Maine, Orono,

ME 04469-5793. Tel (207) 581-1465 Fx (207) 581-2074

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Combining two materials with compatible and complementary physical andmechanical properties can significantly improve construction efficiencies. In the mid-19th Century, reinforcing concrete with steel significantly changed building and bridgeconstruction throughout the world. The keys to the continued success of reinforcedconcrete are the high compressive strength and the low cost of concrete, the high tensilestrength of steel which compensates for the low tensile strength of concrete, the bondstrength between the two materials, and the compatibility between the thermal expansionproperties of steel and concrete.

As the 20th Century ends, many of the factors that contributed to the success ofreinforced concrete are found in reinforcing wood with Fiber Reinforced Polymers(FRPs). Lower grades of wood have high compressive strength and low cost; FRPs havehigh tensile strength which compensates for the lower tensile strength of (low-grade)wood; and FRPs are a very flexible class of materials which can be engineered to insurecompatibility with the properties of wood.

Studies in the past several years by the University of Maine (UM) and others haveshown the significant promise of combining wood and FRP [Triantafillou et al. (1991 and1992); Plevris et al. (1992); Davalos et al. (1992 and 1994); Leichti et al. (1993); Sonti etal. (1995); Chajes et al. (1995); Plevris et al. (1995); Dailey et al. (1995); Hernandez etal. (1997)]. As described later in the paper, the UM studies have demonstrated, forexample, that GFRP reinforcement ratio in the order of 3% can increase the allowablebending strength of glulam beams by over 100%. In keeping with reinforced concreteterminology, the reinforcement ratio is defined as the cross-sectional area of the FRRreinforcement divided by the cross-sectional area of the wood above the reinforcement.

This paper is limited to the short-term ultimate bending strength of reinforced gluedlaminated beams. It briefly introduces a probabilistic nonlinear computer model,ReLAM, which calculates the Probability Density Functions (PDF) of the Modulus ofRupture (MOR) and Modulus of Elasticity (MOE) of reinforced glulam beams. ThesePDFs may be used to develop either LRFD or ASD design methodologies for reinforcedglulam beams. The paper focuses on comparing ReLAM’s ultimate strength and stiffnesspredictions with laboratory test results of 102, 21 ft long glulam beams.

While this paper focuses on predicting the short-term mechanical properties ofreinforced glulams, a basic understanding of long-term behavior is a fundamentalengineering issue that still must be addressed before this technology can be used in bridgeapplications. The long-term durability issues are under active investigation and resultswill be reported in future papers.

SIGNIFICANCE TO TRANSPORTATION INFRASTRUCTURE

FRP-glulams can have a significant impact on the way wood is used for timber bridgeconstruction in the future. There are many engineering, economic and environmentalreasons to combine FRP and wood:

1. Increase strength and stiffness.

2. Increase ductility, which provides a safer failure mechanism.3. Reduce variability in mechanical properties which allows for higher design values4. Allow for use of low-grade wood in construction.5. Improve structural efficiency and reduce structural member size requirements and

weight. For example, depth reduction provides advantages in meeting bridgehydraulic requirements.

6. Improve serviceability by reducing creep deflections.7. Reduce costs under certain conditions.8. Reduce pressure on wood supply, as a result of items (4) and (5) above. This

matches the trends in resource availability of smaller diameter, lower qualitywood.

WHY FRP VERSUS METALLIC REINFORCEMENT?The idea of reinforcing wood is not new. Many studies on wood reinforcement have

been performed in the past 40 years [Bulleit (1984)]. Often metallic reinforcement wasused including steel bars, prestressed stranded cables, and stressed or unstressed bondedsteel and aluminum plates [e.g. Boomsliter (1948); Mark (1961 and 1963); Bohanan(1962); Sliker (1962); Peterson (1965); Lantos (1970); Krueger (1973, 1974a and 1974b);Stern and Kumar (1973); Coleman (1974); Hoyle (1975); Kobetz and Krueger (1976);Taylor et al. (1983); Dziuba (1985); Bulleit et al. (1989); and Dagher et al. (1991)].While significant increase in strength and stiffness has been achieved, the problemsencountered were generally related to incompatibilities between the wood and thereinforcing material. Wood beams reinforced with bonded aluminum sheets experiencedmetal-wood bond delamination with changes in moisture content of only a few percent[Sliker (1962)]. The differences in hygro-expansion and stiffness between the wood andreinforcing materials can lead to separation at the glue-line, or tension failure in the woodnear the glue-line.

To improve durability, fiberglass has been used in a number of ways such as for beamreinforcement, as face material of wood-core sandwich panels, as external reinforcementfor plywood, and in the form of prestressed strands [e.g. Wangaard (1964); Biblis (1965);Theakston (1965); America Plywood Association (1972); Mitzner (1973); Boehme andShultz (1974); Saucier and Holman (1975); Steinmetz (1977); Bulleit (1981); Spaun(1981); Tingley (1987); Davalos et al. (1992); Kimball (1995); and Dagher et al. (1996b,1996c, 1997a, 1997b)]. Unlike traditional steel and aluminum reinforcement, FRPreinforcement of wood composites can be successful because

• The physical/mechanical/chemical properties of the FRP are very versatile. TheFRP may be engineered to match and complement the orthotropic properties ofwood; consequently, bond incompatibility problems between the wood and thereinforcing FRP are minimized.

• FRP materials (fibers/matrix) can be readily incorporated into many of themanufacturing processes currently used to produce glulam beams.

Because AWC materials take advantage of the better physical and mechanicalattributes of both wood and FRPs, they result in performance/cost ratios that are superior

to conventional structural wood composites. The cost/performance advantages of FRP-wood hybrids is expected to improve with time, because long-term trends indicate thatthe cost of wood is increasing due to rising population and demand, while FRP materialcosts are on the decline. FRP material suppliers are switching from low-volume, high-cost defense applications to high-volume, low-cost civil infrastructure markets.

ReLAM: A PROBABILISTIC ULTIMATE STRENGTH MODEL FORREINFORCED GLULAM BEAMS

Glulam beams reinforced on the tension side behave in many ways like reinforcedconcrete (Figure 1). As in reinforced concrete, the reinforcement ratio is defined as thecross-sectional area of the FRP divided by the cross-sectional area of the wood above theFRP. Glulam beams can be under-reinforced, balanced, or over-reinforced. In under-reinforced glulam beams (low levels of tension reinforcement), tension failure of the FRPor the wood can occur. In over-reinforced glulam beams (high levels of tensionreinforcement), ductile compression failure of the wood occurs. In a balanced beam, thewood reaches its maximum compressive strength at the same time as the FRP reaches itsmaximum tensile strength. Therefore, unlike reinforced concrete, over-reinforced glulambeams have a ductile failure mode, whereas under-reinforced glulam beams have a brittlefailure mode.

Modeling reinforced glulam beams through failure requires constitutive relations forthe wood lamstock in both tension and compression, constitutive properties of the FRP intension, as well as the probability density functions of the mechanical properties. Sinceover-reinforced beams fail in compression, the nonlinear constitutive properties of thewood in compression are used. A computer program, called ReLAM, which stands forREinforced LAMinated beams, was developed to conduct the analysis. ReLAMgenerates a nonlinear moment-curvature relationship for the beam then integrates this toobtain the load-deflection relationship through failure (Dagher et. al. 1995a).

ReLAM uses Monte Carlo simulation techniques to predict the strength and stiffnessof a population of reinforced glulams. ReLAM requires as input the probabilitydistributions of both the lamstock and the FRP mechanical properties including Modulusof Elasticity (MOE), Ultimate Tensile Strength (UTS), and Ultimate CompressionStrength (UCS).

Once verified against full-scale test data across a range of beam sizes, FRP types, andwood species, ReLAM will be used to develop AASHTO design property tables for FRP-glulam beams. The beam design properties will be based on the gross cross-section.Bridge designers will in turn use these tables in very much the same way as theycurrently use design tables for conventional (unreinforced) glulam beams. Therefore, tothe bridge designer, there should be no difference in the static design of reinforced andunreinforced glulams. The reinforced glulam tables generated by ReLAM will simplyprovide higher bending strength and MOE values than traditional glulam beams.

FULL-SCALE BEAM TESTS USED TO VERIFY ReLAM

A physical test program was carried out to verify the validity of the computerprogram ReLAM. One hundred and two, 22 feet long, 5 1/8inch x12 inch glulam beamswere fabricated by Willamette Industries. Half were western hemlock and the other halfwere Douglas fir. Three GFRP reinforcement ratios (0%, 1.1%, and 3.3%) were used foreach species. The GFRP reinforcement had a mean ultimate tensile strength of 106 ksiand a tension modulus of elasticity of 6,300 ksi. The transverse properties of the GFRPare negligible since the fibers are unidirectional.

The GFRP was placed directly above the lowest wood lamination in the beam(hereafter called bumper-lam). The size of the bumper-lam was adjusted so that the totaldepth of each beam remained at 12 inches. The bumper-lam is used to protect the FRPduring transportation and construction operations, and to provide fire and UV protection.A random lay-up of special L2/L3 lamstock grade was used in all beams.

• Ninety (90) of the one-hundred and two (102) beams were tested under static load tofailure. The static flexure tests were performed in accordance with ASTM D198:Standard Methods of Static Tests of Lumber in Structural Sizes (4-point bending).

• The twelve (12) remaining beams are currently undergoing an accelerated creep testat the University of Maine, using a load equivalent to 1.25 x (design allowable). Thiscreep test follows procedures in a draft 1998 ASTM standard entitled “StandardSpecification for Evaluation of Duration of Load and Creep Effects of WoodProducts” .

BEAM TEST RESULTS

The laboratory beam test results were used to calculate the following beam properties.The Modulus of Elasticity (MOE) was calculated from the initial linear-elastic slope ofthe load deflection curve. Two values of the Modulus of Rupture were calculated: Onevalue is based on the gross cross section at bumper-lam failure (MORb), and the othervalue is based on the reduced section modulus (without the bumper-lam) at ultimatefailure (MORult). This was done to evaluate the performance in the absence of a bumper-lam. Table 1 summarizes the beam test results.

Using the mean ultimate bending stresses and the Coefficients of Variation (COVs)from Table 1, the allowable bending stresses were determined using methods in ASTMD3737. The allowable bending stress is the 5% lower tolerance limit (LTL) with 75%confidence, divided by 2.1. The 5% LTL with 75% confidence was calculated using asample size of 15 beams following ASTM D2915:

Test 5% LTL MOR = MeanMOR(test) - 1.991 * STDVMOR(test) Eqn. (1)

Fb = Test 5% LTL MOR/2.1 Eqn. (2)

In which 2.1 represents a combination load duration factor (1.6) and safety factor (1.3).

The bumper lamination, the wood lamination below the FRP, fails before the ultimatestrength of the beam is reached. Therefore, one may define a serviceability limit state atthe bumper lam failure, followed by a strength limit state when the beam reaches itsmaximum load. To identify both limit states in design, the corresponding allowablestresses were calculated based on the gross section at bumper lam failure (Fb-bumper), andbased on the reduced section at ultimate failure (Fb-ult). Table 2 summarizes the allowablestress results.

PROPERTIES OF LAMINATING STOCKApproximately 1500 board feet (BF) were selected at random out of the L2/L3

lamstock used to fabricate the test beams. The lamstock had been tested for MOE byWillamette Industries and the MOE was recorded for each lamstock specimen. Themajority of the specimens consisted of 13-foot long 2x6’s. In total, there were (50)Douglas Fir specimens, and fifty (50) Western Hemlock specimens.

Compression Testing: A one-foot long specimen was cut from one end of each 13-ftlamstock specimen (see Figure 2) for compression testing. The resulting 100 one-footlong specimens were tested in compression parallel to grain. The gage length for thedisplacement measurements was 9 inches. The tests were performed in accordance withASTM D198.

Tension Testing: The 100, twelve (12) foot long, specimens were tested for tensionparallel to grain using a 7-ft length between the grips. Deflection under tensile loadingwas measured using two extensometers with a 6-ft gage length. The tests wereperformed in accordance with ASTM D198.

In summary, the following mechanical properties were obtained:

1. MOE: Modulus of Elasticity (Table 3)2. UTS: The Ultimate Tensile Stress parallel to grain (Table 3).3. UCS, Compression stress-strain curve: The Ultimate Compression Stress parallel to

grain and the full stress-strain curve in compression parallel to grain. The data wereobtained by testing one-foot long lamstock specimens to failure in compressionparallel to grain. Using this data, the falling slope of an approximated bilinear stress-strain curve was obtained [Dagher (1998b)].

4. The correlations between MOE, UTS, and UCS (Table 4).

ACCURACY OF RELAM PREDICTIONSReLAM was used to predict the strength and stiffness of the beams described in

sections 2, 3, and 4. ReLAM uses Monte Carlo simulations to generate the mechanicalproperties of a single beam cross section (see Figure 3). The lumber properties used inthe simulations are given in Tables 3 and 4. ReLAM requires the following input:

1. MOE: Mean and COV for each species and grade of wood, and the reinforcement.2. UTS: Mean and COV for each species and grade of wood, and the reinforcement.3. UCS: Mean and COV for each species and grade of wood.

4. Correlations between MOE, UTS, &UCS for each species and grade of wood.5. Descending Slope of the Bilinear Stress-Strain Curve for wood in compression.6. Ultimate Compression Strain for wood at extreme compression fiber of beam at

beam failure.

After generating the mechanical properties for the section shown in Figure 3, ReLAMuses a nonlinear moment-curvature method to analyze the section in bending. ReLAMobtains the load deflection curve for a beam from initial loading until the strength limitstate is reached. It accounts for progressive failure of the tension laminations andcompression yielding of the wood.

Using ReLAM, 500 beam simulations were performed for each beam type tested.The mean and COV of MOE and Ultimate Modulus of Rupture (MORult) were calculatedfor the 500 simulated beams and compared with the laboratory data for the 90 testedbeams (15 samples for each of six beam types). The results are given in Tables 5 and 6.

The design MOE for the simulated beams is the mean value. The allowable bendingstress for the simulated beams is the 5% LTL of the beam MOR divided by a factor of2.1. From ASTM D2915 Table 3, the 5% LTL with 75% confidence in a data set of 30(the total number of compression lamstock samples tested) is:

Test 5% LTL MOR = MeanMOR(test) - 1.869 * STDVMOR(test) Eqn. (3)

Equation (2) was used to calculate Fb for the simulated beams. Table 7 gives the testvalues for MOE and Fb-ult and those values predicted by the computer model. The Tableshows that ReLAM predicted the beam MOE within 5.7% and in most cases within 1%.ReLAM predicted the allowable bending stress of the reinforced beams within –5.5% to6.7%. It should be noted that ReLAM is only intended for the analysis of reinforcedglulams. This data shows that ReLAM is very accurate in predicting the MOE and Fb forreinforced glulam beams.

DURABILITY AND DEMONSTRATION PROJECTS

As part of the UMaine-FWHA contract to develop bridge design specifications forFRP-reinforced glulam bridges, ten FRP-glulam girder bridges will be constructed andmonitored throughout the US. The bridges will be placed in different environments,constructed of different wood species, and subjected to different traffic loadings. Forsafety reasons, the girders will be designed such that they will carry at least 1.25 timesthe unfactored dead and live load in case of failure of the FRP.

Collectively these ten bridges will provide a statistically significant database to assessthe durability of the FRP-glulam girders under actual end-use environments. The majorconcern is the durability of the FRP-wood bond line under the combined effects offatigue loading and hygro-thermal cycling. The durability data from the bridge tests willbe used to verify and validate accelerated environmental weathering tests planned to beconducted in the laboratory. Because of the highly variable nature of the physical andchemical degradation processes and the path-dependent nature of these processes, it is

critical that a statistically significant number of bridges be constructed and monitored.Ten bridges is considered as a minimum number to provide a level of confidencesufficient to draw conclusions.

The ten demonstration bridges are planned to be constructed using IBRC fundingproposals, augmented by local funding as available. All bridges will be monitored byresearchers located in the vicinity of the bridges. Monitoring data will be providedannually to the University of Maine researchers. University of Maine and FHWApersonnel are actively contacting states to participate in this National effort. Themonitoring efforts will be coordinated by researchers at the University of Maine to insureuniformity and completeness of data collection. The following data will be collected onall bridges:

1. Delamination progress of the FRP-wood bond line2. Stiffness degradation of the FRP-glulam girders3. Girder moisture content4. Ambient temperature and relative humidity5. Creep deflections6. Strains in the FRP

University of Maine researchers will assist all participants in the design of the FRP-glulam girders and will provide Q/C personnel during manufacturing. As of this writing,participating state DOTs include Maine (four highway bridges), Alabama (one highwaybridge), and Iowa (one highway bridge).

In an independent effort, three FRP-glulam demonstration structures have beenconstructed in Maine since 1995: the 124 ft long Bar Harbor Yacht Club Pedestrian Pierin Bar Harbor, Maine (1995); the 54 ft long Pattagumpus Vehicular Bridge in Medway,Maine (1997); and the 44 ft long West Seboeis Stream Vehicular Bridge in Seboeis,Maine (1998). These bridges are currently being monitored by the University of Maine,and will help augment the national database on the performance of FRP-glulam bridges.

CONCLUSIONS

The laboratory testing program of one-hundred-and-two, 22 ft long reinforced glulambeams demonstrated that it is possible to produce high performance glulam beams (Fb =3500 psi) using low grade wood. This technology may permit a wider use of glulambeams in highway bridge applications.

The ReLAM model developed at the University of Maine was able to predict themean MOE for the reinforced Doug-fir and Hem-fir beams within 6%, and the allowablebending strength for the reinforced Doug-fir and Hem-fir beams within 7% of the testdata. This demonstrates that the probabilistic nonlinear approach used is an accuratemethod to analyze FRP-glulam beams. The model needs further verification by testinglarger-size beams to account for size and volume effects. Once this is accomplished, themodel will be used as a basis to develop reinforced glulam design tables for theAASHTO code. The computer model will also be available for engineers and

practitioners through the University of Maine Advanced Engineered Wood CompositesCenter.

In addition to static design, evaluating the durability of the FRP and the durability ofthe FRP-wood bond under fatigue loading, environmental degradation, and chemicalattack are integral parts of the on-going research work. These physical and chemicaldegradation processes are complex and path-dependent. Performance-based test methodsare being considered in evaluating both short- and long-term performance at the materialand structural level. In addition, appropriate methods for evaluating the simultaneouseffects of mechanical loading and environmental degradation are under study. Becauseof the complexity of the degradation mechanisms in a bridge environment, tendemonstration bridges will be constructed throughout the US to verify the degradationmodels and supplement the accelerated laboratory testing.

ACKNOWLEDGEMENTSThis work is being conducted in cooperation with the FHWA (S. Duwadi and J.

Hooks program managers), The FHWA Maine Office (Paul Lariviere and GeorgePoirier), the Maine DOT (Steve Abbott, John Buxton, and Dale Peabody), APA theEngineered Wood Association (T. Williamson and B. Yeh), the Market DevelopmentAlliance of the FRP Composites Industry (D. Barno and J. Bussell), the USDA ForestProducts Lab (M. Ritter), Strongwell (H. Taylor), Willamette Industries (T. Karshnesky,W. Tjoelker and D. Soderquist), Georgia Pacific Resins, and Johns Manville (J. McGue).Additional funding for the work was also provided by the National Science Foundation(J. Scalzi and R. Anderson).

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Table 1: Test Results - Ultimate Strength and MOE

Test Group MORb

GrossSection

MORult ReducedSection

BeamDesignation

Samplesize

Mean(psi)

COV(%)

Mean(psi)

COV(%)

W Hem Control 15 4,338 15.4 N/A N/A1.1% W Hem 15 4,794 15.3 6251 17.03.3% W Hem 15 5,521 10.9 8357 12.7Doug-fir Control 15 4,309 11.5 N/A N/A1.1% Doug-fir 15 5,044 19.2 6,656 9.83.3% Doug-fir 15 5,755 13.4 8,844 8.9

Table 2: Test Results: Allowable Stresses, MOE, and Performance Gains

Test Group Mean MOE Fb-bump

Gross SectionFb-ult

ReducedSection

BeamDesignation

SampleSize (x 106 psi)

%Gain (psi)

%Gain (psi)

%Gain

W Hem Control 15 1.32 - 1,433 - N/A -1.1% W Hem 15 1.41 6.8% 1587 10.7% 1,970 37.5%3.3% W Hem 15 1.51 14.4% 2,058 43.6% 2,975 108%Doug-fir Control 15 1.49 - 1,581 - N/A -1.1% Doug-fir 15 1.58 6.0% 1,483 -6.2% 2,553 61.5%3.3% Doug-fir 15 1.74 16.8% 2,010 27.1% 3,466 119%

Table 3: Mechanical Properties of Lamstock in Test Beams

Douglas Fir Western HemlockDatapoints(number)

Mean(psi)

COV(%)

Datapoints(number)

Mean(psi)

COV(%)

MOE 50 1.54 x 106 10.2 50 1.41 x 106 10.0UTS1 foot 50 4,067 24.4 50 4,712 31.8UCS 30 6,447 13.2 30 5,982 14.2

Table 4: Correlation Matrix of MOE, UTS & UCS

Doug Fir Western HemlockMOE UTS UCS MOE UTS UCS

MOE 1.0 0.22 0.11 1.0 0.50 0.46UTS 0.22 1.0 0.20 0.50 1.0 -0.13UCS 0.11 0.20 1.0 0.46 -0.13 1.0

Table 5: Comparison of Experimental & ReLAM Results for Doug-fir

1.1% Doug-fir 3.3% Doug-firTest ReLAM Test ReLAM

Mean MOE (x106 psi) 1.58 1.59 1.74 1.74COV MOE (%) 6.71 5.30 8.02 4.57Mean MORult (psi) 6656 6261 8844 9062COV MORult 9.78 10.19 8.90 7.67

Table 6: Comparison of Experimental & ReLAM Results for Western Hemlock

1.1% W Hem 3.3% W HemTest ReLAM Test ReLAM

Mean MOE (x106 psi) 1.41 1.33 1.51 1.50COV MOE (%) 5.74 5.85 8.11 6.01Mean MORult (psi) 6251 5853 8357 7854COV MORult 16.98 15.52 12.68 10.71

Table 7: ReLAM Predictions versus Test Results

Test Group Mean MOE(x 106 psi)

Fb-ult

Reduced Section(psi)

BeamDesignation

LabSample

Size

Number ofReLAM

Simulations

LabTest

ReLAM %Diff

LabTest

ReLAM %Diff

1.1% WH 15 500 1.41 1.33 -5.7% 1970 1926 -2.2%3.3% WH 15 500 1.51 1.50 -0.7% 2975 2942 -1.1%1.1% DF 15 500 1.58 1.59 -0.6% 2553 2413 -5.5%3.3% DF 15 500 1.74 1.74 0% 3466 3697 6.7%

Figure 1. Reinforced Glulam Beam

Figure 3: Simulation of Beam Cross-Section Properties

12 foot long tension test 1 foot longcompression

test

13 foot long 2x6 (Doug Fir & West Hemlock) MSR

Figure 2. Lamstock Test Specimens

1

2345678

FRP

For each lamination (#1 to #8), anMOE, UTS, and UCS are generatedbased on the Mean, COV, andCorrelation matrix obtained in thetesting of the Douglas Fir andWestern Hemlock lamstock.

Tension

Compression

GFRP