Tributary Load Calculator
Choose beam or column mode. Enter dead and imposed area loads separately and supply the matching tributary geometry.
A QUICK WALKTHROUGH
How to use this tool
- For a beam, enter span and tributary width; for a column, enter tributary widths in two directions.
- Enter dead and imposed area loads separately. Optionally enter member self-weight as force per length for a beam or force for a column.
- Review tributary area, each load component, unfactored totals, and beam reactions or column axial load.
Formula and sources
Beam: q_D,member = q_D × b + w_D; q_I = q_I × b; A_trib = b × L; R_A = R_B = (q_D,member + q_I) × L / 2. Column: A_trib = b_x × b_y; N_D = q_D × A_trib + W_D; N_I = q_I × A_trib; N_total = N_D + N_I. Load transfer: UMass Amherst https://www.umass.edu/bct/publications/articles/calculating-loads-on-headers-and-beams/. Uniform-load simple-support reactions R=wL/2: University of Colorado Boulder https://www.colorado.edu/program/ide/sites/default/files/attached-files/introductory_engineering_design_textbook_0_0.pdf.
Input limits and scope
Finite values only; beam span and tributary dimensions must be positive. Optional member self-weight must be nonnegative. User supplies and keeps units consistent. Beam assumes a simply supported span with uniform full-span load, giving equal end reactions. Column axial loads use rectangular tributary area. No code factors, load combinations, bending, shear, deflection, stability, or load-path checks.
GOOD TO KNOW
Common questions
Are code load factors included?
No. Dead and imposed loads are shown separately, with an unfactored sum.
Does this replace structural design?
No. It does not check bending, shear, deflection, stability, load paths, or code requirements.