CLT Properties Calculator to ANSI/APA PRG 320

This calculator computes geometric and strength properties of CLT panels based on the CLT grade and lay-up selected. Units are in the imperial system. Calculator is for use in the U.S.
📝 This calculator has been written in accordance with ANSI/APA PRG 320-2019, the American National Standards Institute / American Plywood Association Standard for Performance-Rated Cross-Laminated Timber. 
CalculationInputsSelect CLT grade:
﻿﻿CLT Grade
:E2​
﻿
List of CLT grades as per ANSI/APA PRG 320
﻿
Define CLT lay-up:
﻿﻿No. of ply
:3​
﻿
﻿﻿tp
:4.125​
﻿
﻿
OutputsProperties in the major strength direction:
﻿
1.5​
1650​
3825​
102​
0.53​
1980​
Properties in the minor strength direction:
﻿
1.4​
525​
165​
3.6​
0.56​
660​
﻿
ExplanationCross Laminated Timber (CLT) is a prefabricated engineered wood product that consists of at least three layers of solid-sawn lumber. These adjacent layers are cross-oriented and bonded with a structural adhesive to form a solid wood element. It is used in construction for various purposes including structural supports, floors, and walls. 
ANSI/APA PRG 320 refers to out-of-plane bending and shear action as "flatwise", that is the bending and shear produced from transverse (aka perpendicular) loads.
﻿
Load perpendicular to the CLT panel producing "flatwise" bending and shear as per ANSI/APA PRG 320
Where:
﻿﻿Emajor​=
 modulus of elasticity of the lamination, in psi, in the CLT major strength direction
﻿﻿Fb,major​=
 bending stress of the lamination, in psi, in the CLT major strength direction
﻿﻿(Fb​S)eff,f,0​=
 effective flatwise bending moment of CLT, in Ibf-ft/ft of width, in the CLT major strength direction
﻿﻿(EI)eff,f,0​=
  effective flatwise bending stiffness of the CLT, in Ibf-in.^2  of width, in the CLT major strength direction
﻿﻿(GA)eff,f,0​=
 effective flatwise shear rigidity of CLT, in Ibf/ft of width, in the CLT major strength direction
﻿﻿Vs,0​=
 flatwise shear capacity, in Ibf/ft of width, in the CLT major strength direction
﻿﻿Eminor​=
 modulus of elasticity of the lamination, in psi, in the CLT minor strength direction
﻿﻿Fb,minor​=
 bending stress of the lamination, in psi, in the CLT minor strength direction
﻿﻿(Fb​S)eff,f,90​=
 effective flatwise bending moment of CLT, in Ibf-ft/ft of width, in the CLT minor strength direction
﻿﻿(EI)eff,f,90​=
effective flatwise bending stiffness of the CLT, in Ibf-in.}^2 /ft of width, in the CLT minor strength direction
﻿﻿(GA)eff,f,90​=
 effective flatwise shear rigidity of CLT, in Ibf/ft of width, in the CLT minor strength direction
﻿﻿Vs,90​=
 flatwise shear capacity, in Ibf/ft of width, in the CLT minor strength direction
Code EquationsBelow, we'll present the equations used to calculate each key property of the CLT panel, as per ANSI/APA PRG 320.
Flatwise Bending Moment
﻿
(FbS)eff,0=(112)0.85Fb,majorSeff,0[X3-1 ASD](FbS)eff,90=(112)Fb,minorSeff,90[X3-2 ASD](F_bS)_{\text{eff},0} = \left( \frac{1}{12} \right) 0.85 F_{b,\text{major}} S_{\text{eff},0} \hspace{1cm} \text{[X3-1 ASD]}\\(F_bS)_{\text{eff},90} = \left( \frac{1}{12} \right) F_{b,\text{minor}} S_{\text{eff},90} \hspace{1cm}  \text{[X3-2 ASD]} (Fb​S)eff,0​=(121​)0.85Fb,major​Seff,0​[X3-1 ASD](Fb​S)eff,90​=(121​)Fb,minor​Seff,90​[X3-2 ASD]
Flatwise Bending Stiffness
﻿
(EI)eff,f,0=∑i=1nEib0ti312+∑i=1nEib0tizi2[X3−3](EI)eff,f,90=∑i=2nEib90ti312+∑i=2nEib90tizi2[X3−4](EI)_{\text{eff,f,}0} = \sum_{i=1}^{n} E_ib_0 \frac{t_{i}^{3}}{12} + \sum_{i=1}^{n} E_ib_0 t_{i} z_{i}^{2} \hspace{1cm} [X3-3] \\ (EI)_{\text{eff,f,}90} = \sum_{i=2}^{n} E_ib_{90} \frac{t_{i}^{3}}{12} + \sum_{i=2}^{n} E_ib_{90} t_{i} z_{i}^{2} \hspace{1cm}[X3-4](EI)eff,f,0​=∑i=1n​Ei​b0​12ti3​​+∑i=1n​Ei​b0​ti​zi2​[X3−3](EI)eff,f,90​=∑i=2n​Ei​b90​12ti3​​+∑i=2n​Ei​b90​ti​zi2​[X3−4]
Flatwise Shear Rigidity
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(GA)eff,f,0=(tp−t12−tn2)2[(t12G1b0)+(∑i=2n−1tiGib0)+(tn2Gnb0)][X3−5](GA)eff,f,90=(tp−t12−tn2)2(t12G1b90)+(∑i=2n−1tiGib90)+(tn2Gnb90)[X3−6](GA)_{\text{eff,f,}0} = \dfrac{(t_{p} - \frac{t_{1}}{2} - \frac{t_{n}}{2})^2}{\left[ \left( \frac{t_{1}}{2G_1b_0} \right) + \left( \sum_{i=2}^{n-1} \frac{t_{i}}{G_i b_0} \right) + \left( \frac{t_{n}}{2G_nb_0} \right) \right]} \hspace{1cm} [X3-5] \\ (GA)_{\text{eff,f,}90} = \dfrac{(t_{p} - \frac{t_{1}}{2} - \frac{t_{n}}{2})^2}{\left( \frac{t_{1}}{2G_1b_{90}} \right) + \left( \sum_{i=2}^{n-1} \frac{t_{i}}{G_ib_{90}} \right) + \left( \frac{t_{n}}{2G_nb_{90}} \right)} \hspace{1cm} [X3-6](GA)eff,f,0​=[(2G1​b0​t1​​)+(∑i=2n−1​Gi​b0​ti​​)+(2Gn​b0​tn​​)](tp​−2t1​​−2tn​​)2​[X3−5](GA)eff,f,90​=(2G1​b90​t1​​)+(∑i=2n−1​Gi​b90​ti​​)+(2Gn​b90​tn​​)(tp​−2t1​​−2tn​​)2​[X3−6]
Flatwise (Rolling) Shear Rigidity
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Vs,0=2Agross,03Fs,minor[X3-7 ASD]Vs,90=2Agross,903Fs,major[X3-8 ASD]V_{s,0} = \frac{2 A_{\text{gross,0}}}{3} F_{s,\text{minor}} \hspace{1cm}\text{[X3-7 ASD]}  \\V_{s,90} = \frac{2 A_{\text{gross,90}}}{3} F_{s,\text{major}} \hspace{1cm}\text{[X3-8 ASD]} Vs,0​=32Agross,0​​Fs,minor​[X3-7 ASD]Vs,90​=32Agross,90​​Fs,major​[X3-8 ASD]
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	1.5
	1650
	3825
	102
	0.53
	1980

	1.4
	525
	165
	3.6
	0.56
	660