Floor Beam Calculator

Calculates bending, shear, deflection, and bearing for a simply supported wood beam under uniform load (ASCE 7-16 load combinations).

How to Use This Calculator:

Enter Beam Span: Input the length of the beam in feet and inches.
Enter Tributary Width: Input the width of the floor area (in feet) supported by the beam.
Enter Loads: Input Dead Load (D) and Live Load (L) in pounds per square foot (psf).
Configure Beam: Select Number of Plies, Lumber Type, and Beam Size.
Enter Bearing Length: Input the length of the beam bearing on its supports in inches.
Calculate: Click the "Calculate" button.
Review Results: Check the overall PASS/FAIL status and individual checks for Bending, Shear, Deflection (Live Load & Total Load), and Bearing.

Beam Span ℹ️

Tributary Width ℹ️

Dead Load (D) ℹ️

psf

Live Load (L) ℹ️

psf

Beam Configuration

Plies ℹ️

Lumber

Size

Bearing Length ℹ️

PENDING

Explanation of Calculations:

Factored Load ($w_u$) & Moment ($M_u$): Calculated as before using $1.2D + 1.6L$. $M_u = w_u L^2 / 8$.
Allowable Moment ($M_{allow}$): $F_b \times S$. (No $C_D, C_M, C_t, C_L, C_F, C_i, C_r$ applied to $F_b$)
Max Shear Demand ($V_u$): For a simply supported beam, $V_u = w_u L / 2$.
Actual Shear Stress ($f_v$): For a rectangular section, $f_v = 1.5 \times V_u / A_{total}$, where $A_{total}$ is total cross-sectional area.
Allowable Shear Stress ($F_v'$): Base $F_v$ value. (No $C_D, C_M, C_t, C_i$ applied)
Deflection ($\Delta$): Calculated using unfactored (service) loads. $\Delta = 5 w L^4 / (384 E I)$.
- $w_{LL}$ (for Live Load deflection) = (Live Load psf $\times$ Trib Width) / 12 pli.
- $w_{TL}$ (for Total Load deflection) = ((Live Load psf + Dead Load psf) $\times$ Trib Width) / 12 pli.
- $I$ is the Moment of Inertia ($b_{total}h^3/12$). $E$ is Modulus of Elasticity.
- Typical limits: L/360 for live load, L/240 for total load.
Reaction (R) & Bearing Stress ($f_{c\perp}$): Reaction $R = V_u$. Actual bearing stress $f_{c\perp} = R / A_b$, where $A_b$ is bearing area (Total Beam Width $\times$ Bearing Length).
Allowable Bearing Stress ($F_{c\perp}$): Base $F_{c\perp}$ value. (No $C_b, C_M, C_t, C_i$ applied)

Reference Standards: Load combination from ASCE 7-16. Wood properties and basic formulas from NDS. Always consult local codes.

Design Assumptions & Parameters:

Lumber: SPF #2
- $F_b$: 875 psi (Allowable Bending Stress)
- $F_v$: 135 psi (Allowable Shear Stress)
- $F_{c\perp}$: 425 psi (Allowable Bearing Stress Perp. to Grain)
- $E$: 1,400,000 psi (Modulus of Elasticity)
Actual Beam Dimensions (b x h): 1.5" x 11.25" for 2x12
Load Combination (Strength): $1.2D + 1.6L$. Deflection uses unfactored $D$ and $L$.
Beam is simply supported, uniformly loaded. Lateral torsional buckling not checked ($C_L=1.0$ assumed).
No adjustment factors ($C_D, C_M, C_t, C_F, C_r, C_i, C_b$) are applied to design values. This is a simplified check. For a complete design, these factors must be considered per NDS.
Beam self-weight should be included in the Dead Load (psf) by the user.

Disclaimer: For Preliminary Estimating Purposes Only

This calculator is for preliminary informational purposes only and should not substitute professional engineering design. All designs must be verified by a qualified engineer considering all applicable codes, standards, and site-specific conditions. No liability is assumed for its use.

Floor Beam Calculator

How to Use This Calculator:

Beam Configuration

Calculation Summary

Bending Moment Check

Shear Force Check

Deflection Check (Service Loads)

Bearing Check (Perpendicular to Grain)

Explanation of Calculations:

Design Assumptions & Parameters:

Disclaimer: For Preliminary Estimating Purposes Only