wood design aid

8/3/2019 Wood Design Aid

1/12

Applicability of Adjustment Factors to Reference Design Values

Adjustment Factor Fb Ft Fv Fc Fc E EminCD Load Duration x x x - x - -

C

M

Wet Service x x x x x x x

Cb Bearing Area - - - x - - -

CL Beam Stabilitya x - - - - - -

CP Column Stability - - - - x - -

Ct Temperature x x x x x x x

Ci Incising b x x x x x x xCF Size

cx x - - x - -

Cr Repetitive Memberd x - - - - - -

Cf

u

Flat Use e x - - - - - -

Cv Volumea x - - - - - -

Cc Curvaturef x - - - - - -

a. When applied to Glued Laminated Lumber only the lesser of CL or Cv is applicable

b. Applies to incised sawn lumber

c. Applies to visually graded lumber

d. Applies to dimension lumber

e. Applies to dimension lumber and glued laminated members

f. Applies to curved glued laminated members

Applicability of Adjustment Factors

LoadDuration

W

etService

Temperature

B

eamStability

Size

FlatUse

In

cising

R

epetitiveMember

C

olumnStability

B

earingArea

V

olume

C

urvature

CD CM

Ct CL CF Cfu Ci Cr CP Cb Cv Cc

Visually Graded Dimension Lumber

Tables 4A, 4B, 4Fx x x x x x x x x x - -

Mechanically Graded Dimension Lumber

Table 4Cx x x x - x x x x x - -

Visually Graded Timber 5x5 and larger

Table 4Dx x x x x ? x - x x - -

Visually Graded Decking

Table 4Ex x x x x - x - x x - -

Glued Laminated Timber

Tables 5A, 5B, 5C, 5Dx x x xa - x - - x x xa x

a. When applied to Glued Laminated Lumber only the lesser of CL or Cv is applicable


2/12

Column Glued Laminated Timber

Given: Nominal Size, Length, Species

1. Get Green Dressed Size NDS-SUPP Table 1A example: 6 x 10 = 5-5/8 x 9-1/2

2. Get Fc andEmin Reference Design Values NDS-SUPP Tables 5A to 5D

3. Need these Values:CD = Load Duration Factor Establish per ASCE-ASD load combinationsCMc = Wet Service Factor for Fc if >16%CMEmin = Wet Service Factor for Emin if > 16%

Ctc = Temperature Factor for Fc NDS-Table 2.3.3

CtEmi n = Temperature Factor forEmin NDS-Table 2.3.3

4. )(* ctcMcDc FCCCF =

5.minminmin

'

min

ECCEtEME

=

6. lKl ee = = Effective length ofColumn Must check both, x and y axes.

111 lKl ee = and 222 lKl ee = see SERM page 5-12 or NDS page 156 for Ke

7. Calculated

le = The larger of

1

11

d

lKe and

2

12

d

lKe d1 and d2 columnd dimensions.

8. The critical buckling design value 2

'

min822.0

=

d

l

EF

e

cE

9.*

'

c

cE

F

FF =

10. Column Stability Factor c

F

c

F

c

FCp

'2

''

2

0.1

2

0.1

+

+=

8.0=c for sawn lumber

11. The adjusted valueis: )(' cptcMcDc FCCCCF =

*'

cpc FCF =

12. The allowable capacity of the Column: AFPcal

'=

Fc E and Emin

0.73 0.833

Reference Design Value Moisture Condition 100F < T 125F 125F < T 150F

E , Emin Wet or Dry 0.9 0.9

FcDry 0.8 0.7

Wet 0.7 0.5


3/12

Column Round Timber Pole and Piles


1. Get Fc andEmin Reference Design Values NDS Tables 6A and 6B pg-392. Need these Values:

CD = Load Duration Factor Establish per ASCE-ASD load combinationsCtc = Temperature Factor for Fc NDS-Table 2.3.3CtEmi n = Temperature Factor forEmin NDS-Table 2.3.3

Cu= Untreated Factor NDS Table 6.3.5 (page-40)

Species Cu

Pacific Coast Douglas Fir, Red Oak, Red Pine 1.11

Southern Pine 1.18

Cp = Column Stability Factor see below

Ccs = Critical Section Factor NDS 6.3.9

( )( ) 10.1002.00.1 += ccs LC Lc= Length from tip of pile to critical section, ftCsp = Single Pile Factor For Piles, see Table 6.3.11page-41 (For Poles Table 6B, Csp = 1.0)

4. )(* cspcsutcDc FCCCCCF =

5. minmin'

min ECE tE=

6. lKl ee = = Effective length of Column see SERM pg 5-12 or NDS pg 156 for Ke


'

min822.0

=

dl

EF

e

cE 3rd = for round column

8.*

'

c

cE

F

FF =


F

c

F

c

FCp

'2

''

2

0.1

2

0.1

+

+=

8.0=c 5 for round timber poles and piles

10. The adjusted value is: )(' cspcsputcDc FCCCCCCF =

*'cpc FCF =

11. The allowable capacity of the Column: AFP cal'

=



FcDry 0.8 0.7

Wet 0.7 0.5

Reference Design Value Csp

Fc 0.80Fb 0.77


4/12

Column Visually Graded Dimension Lumber


1. Get Dry Dressed Size NDS-SUPP Table 1A example: 2 x 8 = 1.5 x 7.252. Get Fc andEmin Reference Design Values NDS-SUPP Tables 4A,4B, 4F

3. Need these Values:CD = Load Duration Factor Establish per ASCE-ASD load combinations

CMc = Wet Service Factor for Fc if >19%

CMEmin = Wet Service Factor for Emin if > 19%Ctc = Temperature Factor for Fc NDS-Table 2.3.3CtEmi n = Temperature Factor forEmin NDS-Table 2.3.3

CF = Size Factor NDS-SUPP Tables 4A,4B, 4FFor members exceeding 12 in depth and 5 in thickness CF = (12/d)

1 / 9

Cic = Incising Factor for F c Table 4.3.8

CiEmin = Incising Factor for Emin Table 4.3.8

4. )(*cicFtcMcDc

FCCCCCF =

5. minminminmin'

min ECCCE iEtEME=



7. Calculated

le = The larger of1

11

d

lKe and2

12

d



'

min822.0

=

dl

EF

e

cE

9.*

'

c

cE

F

FF =


F

c

F

c

FCp

'2

''

2

0.1

2

0.1

+

+=


11. The adjusted valueis: )(' cpicFtcMcDc FCCCCCCF =

*' cpc FCF =


=

Fc E and Emin

0.80* 0.9

* When (Fc)( CF) 750 psi, CM = 1.0



FcDry 0.8 0.7

Wet 0.7 0.5

E , Emin 0.95Fc 0.80


5/12

Column Visually Graded Timbers 5x5 and Larger



2. Get Fc andEmin Reference Design Values NDS-SUPP Tables 4D


CMc = Wet Service Factor for Fc if >19%

CMEmin = Wet Service Factor for Emin if > 19%Ctc = Temperature Factor for Fc NDS-Table 2.3.3CtEmi n = Temperature Factor forEmin NDS-Table 2.3.3

CF = CF = (12/d)1 / 9

Cic = Incising Factor for F c Table 4.3.8 CiEmin = Incising Factor for Emin Table 4.3.8

4. )(*cicFtcMcDc

FCCCCCF =

5. minminminmin'

min ECCCE iEtEME=



7. Calculated

le = The larger of1

11

d

lKe and2

12

d



'

min822.0

=

d

l

EF

e

cE

9.*

'

c

cE

F

FF =


F

c

F

c

FCp

'2

''

2

0.1

2

0.1

+

+=


11. The adjusted value is: )(' cpicFtcMcDc FCCCCCCF =

*'

cpc FCF =


=

Fc E and Emin

0.91 1.00



FcDry 0.8 0.7

Wet 0.7 0.5

E , Emin 0.95

Fc 0.80


6/12

Flexure Glued Laminated Timber


1. Get Fb andEmin Reference Design Values NDS-SUPP Tables 5A to 5D

2. Need these Values:

CD = Load Duration Factor Establish per ASCE-ASD load combinationsCMb = Wet Service Factor for Fb >16%

CMEmin = Wet Service Factor for Emin

>16%

Ctb = Temperature Factor for Fb NDS-Table 2.3.3 Considedered wet when moisture > 16%CtEmi n = Temperature

Emin Factor for

NDS-Table 2.3.3 wet

when moisture >

16%

CL = Beam Stability Factor ( Check SERM page 5-3 for C L =1.0 >> If the beam is properly

restrained against lateral movement you dont have to calculate C L will save a lot of time).

Beam Stability Factor CL shall not apply simultaneously with Volume Factor C v

Cv = Volume FactorX

vLdb

C

1

5.1291

= L ft d in b in

X = 20 for Southern Pine X=10 for all other species

Cfu = Flat Use Factor NDS-SUPP Tables 5A to 5D

Cc = Curvature Factor, ( )2

20001

=

R

tC

c t = thikness of laminations and R = Radius of

curvature all in inches100

1=R

t for Southern Pine125

1=R

t for other softwoods.

4. )(*bFtbMbDbFCCCCF =

5. minminmin'

min ECCE tEME=

6. le = Effective length of Beam see SERM Page 5-4 (or see NDS Table 3.3.3 is not user friendly)

7. 502

=b

dl

BR e 8.

2

'

min

)(

20.1

B

bER

EF = 9.

*

b

bE

F

FF =

10.

95.09.1

0.1

9.1

0.12

FFFCL

+

+=

11. The allowable adjusted bending stress: Must use the smaller of CL or Cv

)()('

bfuvLtbMbDbFCorCCCCCF =

12. The moment capacity of the beam:

SFMb

'= 6

2bdS =

Fb F t Fv Fc Fc E and Emin

0.8 0.8 0.875 0.53 0.73 0.833

Reference Design Value Moisture Condition 100F < T 125F 125F < T 150FF t , E , Emin Wet or Dry 0.9 0.9

Fb , Fv , Fc , FcDry 0.8 0.7

Wet 0.7 0.5

E , Emin 0.95

Fb , F t , Fc , Fv 0.80


7/12

hit Ctrl + F9.

type eq \f(x,y)Hit Shift + F9 while inside the braces

Fc 1.00


8/12

Flexure Mechanically Graded Dimension Lumber


1. Get Dry Dressed Size NDS-SUPP Table 1A example: 2 x 8 = 1.5 x 7.252. Get Fb andEmin Reference Design Values NDS-SUPP Tables 4C


CMb = Wet Service Factor for Fb if > 19%

CMEmin = Wet Service Factor for Emin if > 19%Ctb = Temperature Factor for Fb NDS-Table 2.3.3 belowCtEmi n = Temperature Factor forEmin NDS-Table 2.3.3 below

NDS-Table 2.3.3

CL = Beam Stability Factor ( Check SERM page 5-3 for C L =1.0 >> If the beam is properly

restrained against lateral movement you dont have to calculate C L will save a lot of time).

CF

= Size Factor = 1.0 for mechanically graded dimension lumber.

For members exceeding 12 in depth and 5 in thickness CF = (12/d)1 / 9

Cfu = Flat Use Factor NDS-SUPP Table 4CCib = Incising Factor for Fb Table 4.3.8 CiEmin = Incising Factor for Emin Table 4.3.8 Cr = Repetitive Member Factor = 1.15

4. )(*bribFtbMbDb

FCCCCCCF =

5. minminminmin'

min ECCCE iEtEME=

6. le = Effective length of Beam see SERM Page 5-4 (see NDS Table 3.3.3 is not user friendly)

7. 50

2

=

b

dl

B

R e 8.2

'

min

)(

20.1

B

bE

R

EF = 9.

*

b

bE

F

FF =

10.95.09.1

0.1

9.1

0.12

FFFCL

+

+=

11. The allowable adjusted bending stress:

bbfuLb

bbribfuFLtbMbDb

FFCCF

FFCCCCCCCCF

=

=

)(

)(

*'

'


SFM b'

= 6

2bd

S =

Fb E and Emin

0.85* 0.9

* When (Fb)( CF) 1150psi, CM = 1.0



FbDry 0.8 0.7

Wet 0.7 0.5

E , Emin 0.95

Fb 0.80


9/12

Flexure Round Timber Pole and Piles


1. Get Fb Reference Design Values NDS Tables 6A and 6B pg-39

3. Need these Values:

CD = Load Duration Factor Establish per ASCE-ASD load combinationsCt b = Temperature Factor for Fb NDS-Table 2.3.3

Cu= Untreated Factor NDS Table 6.3.5 (page-40)

Species Cu

Pacific Coast Douglas Fir, Red Oak, Red Pine 1.11

Southern Pine 1.18

CF = Size Factor When diameter exceeds 13.5 0.1541.13 9

1

=

DCF D = Diameter

Csp = Single Pile Factor For Piles, see Table 6.3.11page-41 (For Poles Table 6B, Csp = 1.0)


)('

bspFutbDb FCCCCCF =


Moment of inertia of cirlcle =4

4r



FbDry 0.8 0.7

Wet 0.7 0.5

Reference Design Value Csp

Fc 0.80Fb 0.77


10/12

Flexure Visually Graded Decking


1. Get Dry Dressed Size NDS-SUPP Table 1A example: 2 x 8 = 1.5 x 7.252. Get Fb andEmin Reference Design Values NDS-SUPP Table 4E



CMEmin = Wet Service Factor for Emin if > 19%Ctb = Temperature Factor for Fb NDS-Table 2.3.3CtEmi n = Temperature Factor forEmin NDS-Table 2.3.3

CL = Beam Stability Factor ( Check SERM page 5-3 for C L =1.0 >> If the beam is properlyrestrained against lateral movement you dont have to calculate C L will save a lot of time).

CF = Size Factor NDS-SUPP Table 4E

Cfu = Flat Use Factor =1.0

Cib = Incising Factor for Fb Table 4.3.8

CiEmin = Incising Factor for Emin Table 4.3.8 Cr = Repetitive Member Factor = 1.0

4. )(* bribFtbMbDb FCCCCCCF =

5.minminminmin

'

minECCCE

iEtEME=

6. le = Effective length of Beam see SERM-Page 5-4 (see NDS Table 3.3.3 is not user friendly)

7. 502

=b

dl

BR e 8.

2

'

min

)(

20.1

B

bER

EF = 9.

*

b

bE

F

FF =

10.95.09.1

0.1

9.1

0.12

FFFCL

+

+=


bbfuLb

bbribfuFLtbMbDb

FFCCF

FFCCCCCCCCF

=

=

)(

)(

*'

'


SFM b'

= 6

2bd

S =

Fb E and Emin

0.85* 0.9

* When (Fb)( CF) 1150psi, CM = 1.0



FbDry 0.8 0.7

Wet 0.7 0.5

E , Emin 0.95

Fb 0.80


11/12

Flexure Visually Graded Dimension Lumber


1. Get Dry Dressed Size NDS-SUPP Table 1A example: 2 x 8 = 1.5 x 7.252. Get Fb andEmin Reference Design Values NDS-SUPP Tables 4A,4B, 4F


CMb = Wet Service Factor for Fb if >19%



CF = Size Factor NDS-SUPP Tables 4A to 4F


Cfu = Flat Use Factor NDS-SUPP Tables 4A,4B, 4FCib = Incising Factor for Fb Table 4.3.8 CiEmin = Incising Factor for Emin Table 4.3.8 Cr = Repetitive Member Factor = 1.15 See Tables too.

4. )(*bribFtbMbDb

FCCCCCCF =

5. minminminmin'

min ECCCE iEtEME=


7. 50

2

=

b

dl

B

R e 8.2

'

min

)(

20.1

B

bE

R

EF = 9.

*

b

bE

F

FF =

10.95.09.1

0.1

9.1

0.12

FFFCL

+

+=


bbfuLb

bbribfuFLtbMbDb

FFCCF

FFCCCCCCCCF

=

=

)(

)(

*'

'


SFM b'

= 6

2bd

S =

Fb E and Emin

0.85* 0.9

* When (Fb)( CF) 1150psi, CM = 1.0



FbDry 0.8 0.7

Wet 0.7 0.5

E , Emin 0.95

Fb 0.80


12/12

Flexure Visually Graded Timbers 5x5and Larger



2. Get Fb andEmin Reference Design Values NDS-SUPP Table 4D





CF = Size Factor NDS-SUPP Table 4D


Cfu = Flat Use Factor NDS-SUPP Table 4DCib = Incising Factor for Fb Table 4.3.8 CiEmin = Incising Factor for Emin Table 4.3.8 Cr = Repetitive Member Factor doesnt apply =1.0

4. )(* bribFtbMbDb FCCCCCCF =

5. minminminmin'

min ECCCE iEtEME=


7. 50

2

=

b

dl

BR

e 8.2

'

min

)(

20.1

B

bE

R

EF = 9.

*

b

bE

F

FF=

10.95.09.1

0.1

9.1

0.12

FFFCL

+

+=


bbfuLb

bbribFLtbMbDb

FFCCF

FFCCCCCCCF

=

=

)(

)(

*'

'


SFM b'

= 6

2bd

S =

Fb E and Emin

1.0 1.0



FbDry 0.8 0.7

Wet 0.7 0.5

E , Emin 0.95

Fb 0.80

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