Spreadsheets for Allowable Stress Design of Beams

Where to Find an Excel Spreadsheet for Allowable Stress Design of Beams

For an Excel spreadsheet for allowable stress design of beamsclick here to visit our spreadsheet store.  Obtain a convenient, easy to use spreadsheet for allowable stress design of beams at a reasonable price. Read on for information about the use of deflection limits and serviceability requirements for simply supported beam design.

Background for Allowable Stress Design of Beams

Design of a simply supported beam with uniform distributed load can be carried out as follows.  Based on inputs of span length, elastic modulus, live load, dead load, allowable bending stress, deflection limit for live load and deflection limit for live load and dead load acting simultaneously, the equations in the next section can be used to calculate maximum moment, maximum shear, elastic section modulus, and minimum moments of inertia required to satisfy the constraints on deflection.  The equations can also be used to check on whether a known design satisfies strength and deflection requirements.

Equations for Allowable Stress Design of Beams

Equations for the first step in allowable stress design of beams calculations are as follows for a simply supported beam subject to a uniform distributed load:

Mmax  =  wL2/8,   where

  • Mmax  =  maximum moment in the beam
  • w  =  distributed load on the beam
  • L  =  length of span

Vmax  =  wL/2, where

  • Vmax  =  maximum shear in the beam
  • w and L are as defined above

Mallow  =  SFb,  where

  • Mallow  =  the allowable moment in the beam
  • S  =  elastic section modulus of the beam
  • Fb  =  maximum allowable stress in the beam

ymax  =  5wL4/(384EI),  where

  • ymax  =  the maximum deflection in the beam
  • E  =  elastic modulus of the beam
  • I  =  moment of inertia of the cross section of the beam

ymax  <  L/Ld,  where

  • Ld is a dimensionless number specified by code, depending on structural application and load type (typically Ld = 120, 180, 240, 360, or 600)


A Spreadsheet for Allowable Stress Design of Beams

The screenshot below shows an Excel spreadsheet for allowable stress design of beams.  Based on inputs of span length, elastic modulus, live load, dead load, allowable bending stress, deflection limit for live load and deflection limit for dead load, the spreadsheet can be used to calculate maximum moment, maximum shear, elastic section modulus, and minimum moments of inertia required to satisfy the constraints on deflection.

For low cost, easy to use spreadsheets to make these calculations in S.I. or U.S. units,  as well as checking with a known design to see if strength and deflection requirements are met, click here to visit our spreadsheet store.

spreadsheet for allowable stress design of beams

About Mark Rossow

Dr. Rossow is a graduate of the University of Michigan with B.S., M.S., and PhD degrees. He is a licensed Professional Engineer in the State of Illinois. He taught civil engineering for over 35 years, including six years at Washington University in St. Louis and 29 years at Southern Illinois University Edwardsville, where he was the Chair of the Civil Engineering Department for ten years. His areas of expertise are in civil engineering and mechanics. He has consulted for various organizations, including government agencies and an international offshore drilling company. He has published many journal articles and technical reports.
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