User Manual
This user manual provides detailed instructions on how to utilize the features of this spreadsheet effectively.
How to Use the Spreadsheet
- The spreadsheet can be found here: beam.xlsx.
- Complete all cells highlighted in pink in the sheet tab “SampleCalc”
- Do not change any other values or add columns to the tables
- Print the “SampleCalc” sheet tab using a Portrait configuration
Inputs Parameters
Element Description Input
- Level: Defines the story where the element is located
- Label: Denotes the tag or mark used for the beam
- Type: Specify if this is a beam, joist, rafter, hip
Design Loads
- M [kip-ft]: Maximum moment acting on the beam
- V [kip]: Maximum shear acting on the beam
- R [kip]: Maxium reaction acting on the beam
Design Geometry Input
- length[ft]: Enter the length of the beam
- bn[in]: Enter the nominal width
- db[in]: Enter the nominal depth
- N: Enter the number of plies
- Lbe [in]: Enter the minimum bearing length for each end
Material Properties Input
Take these values from Reference Design Values
- Species and Commercial Grade: Add the wood species and the grade
- Fb: Bending value (psi)
- Emin: Minimum modulus of Elasticity (psi)
- Fv: Shear parallel to grain (psi)
- E: Modulus of elasticity (psi)
- Fcp: Compression perpendicular to grain (psi)
Wood Adjustment factors
Take these parametersfrom Adjustment Values. Multiply the adjustment factors and the reference design values to obtain the adjusted capacities below.
-
\(C_D\) : Load duration factor. Recommended value: 1 for D+L combination. Refer to (2018 NDS, 2018) - Section 2.3.2
-
\(C_M\) : Wet service factor. Recommended value: 1 for moisture content less than 19% for an extended time period. Refer to (2018 NDS, 2018) - Section 4.3.3
-
\(C_t\) : Temperature factor. Recommended value: 1 for not exposed to temperatures larger than 150 F. Refer to (2018 NDS, 2018) - Section 4.3.4
-
\(C_F\) : Size factor. Recommended value: 1 to be conservative. Refer to (2018 NDS, 2018) - Section 4.3.6
-
\(C_fu \) : Flat-use factor. Assumed value:1. Refer to (2018 NDS, 2018) - Section 4.3.7
-
\(C_i\) : Incising factor. Recommended value: 1 for not incised. Refer to (2018 NDS, 2018) - Table 4.3.8
-
\(C_r \) : Repetitive member factor. Recommended value: 1 to be conservative. Refer to (2018 NDS, 2018) - Section 4.3.9
-
\(C_L \) : Beam Stability Factor. Assumed value:1 since the beam meets the requirements of NDS 2018 Section 4.4.1.2. Refer to (2018 NDS, 2018) - Section 3.3.3.8
-
\(C_b \) : Bearing area factor. Refer to (2018 NDS, 2018) - Section 3.10.4
- \( C_b = \frac{L_{be} + 0.375}{L_{be}} \)
Calculations
The calculations are performed according to these sections:
Output Results
If the DCR for each limit state is less than 1.0, the status is PASS; otherwise, the status is FAIL.
Bending Check
Bending strength \( M_{n} [kip-ft] \)
\[ M_{n} = F'_{b} \cdot S\] \[DCR = \frac{M}{M_{n}} \]Shear Check
Shear strength \( V_{n} [kip] \)
\[ V_{n} = \frac{2}{3} F'_v \cdot b \cdot d \cdot N\] \[DCR = \frac{V}{V_{n}} \]Deflection Check
Deflection demand \( Def_{a} [in] \)
\[ Def_{a} = \frac{LTF \cdot 5 \cdot M \cdot L^2}{24E' \cdot S \cdot d}\]- Assume the long-term factor (LTF) equals 1.2 for conservative results
Deflection limit \( Def_{l} [in] \)
\[ Def_{l} = min(0.75 in, L/240)\] \[DCR = \frac{Def_{a}}{Def_{l}} \]Bearing Check
Bearing Capacity \( B_n [kip] \)
\[ B_{n} = F'_{cp} \cdot b \cdot L{be} \cdot N\] \[DCR = \frac{R}{B_{n}} \]References
2018 NDS. (2018). American Wood Council. https://awc.org/publications/2018-nds/
2018 NDS Supplement. (2021). American Wood Council. https://awc.org/publications/2018-nds-supplement/
ASCE 7-22. (2021). https://www.asce.org/publications-and-news/civil-engineering-source/article/2021/12/02/updated-asce-7-22-standard-now-available
Breyer, D. E., Cobeen, K. E., & Martin, Z. (2017). Design of Wood Structures ASD/LRFD Eighth Edition. https://shop.iccsafe.org/design-of-wood-structures-asd-lrfd-eighth-edition.html
Validation
The spreadsheet was validated using:
- Beam Validation 1 from Example 6.18 (Breyer et al., 2017).