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Timoshenko Beam Shear Deformation Deflection Calculator

Classical Euler-Bernoulli beam theory assumes that plane cross-sections remain perpendicular to the neutral axis, completely neglecting transverse shear deformations.

Length of simply supported beam span.

Concentrated transverse load applied at midspan.

Modulus of elasticity (200 GPa for steel).

Transverse shear modulus (80 GPa for steel).

Second moment of area about bending neutral axis.

Total beam cross-sectional area.

Shear coefficient (5/6 ≈ 0.833 for rectangular cross-section).

Calculated Result
0.644 mm

Total Midspan Deflection

Pure Bending Component

0.625 mm

Shear Deformation Component

0.019 mm

Shear Contribution Percentage

2.9%

Calculation Breakdown

  1. Euler Bending: δ_b = P·L³ / (48·E·I)0.625 mm
  2. Timoshenko Shear: δ_s = P·L / (4·κ·A·G)0.019 mm
  3. Total: δ_total = δ_b + δ_s0.644 mm

What Is the Timoshenko Beam Shear Deformation Deflection Calculator?

Timoshenko beam theory relaxes the Kirchhoff assumption, allowing cross-sections to rotate independently of the slope of the deflection curve due to shear strain.

It provides superior accuracy for stocky beams, high-frequency vibrations, and sandwich panels.

How Does the Timoshenko Beam Shear Deformation Deflection Calculator Work?

Calculates pure flexural bending deflection delta_b = P*L^3 / (48*E*I).

Calculates transverse shear deflection delta_s = P*L / (4*kappa*A*G).

Sums components to yield total Timoshenko deflection and calculates shear percentage.

Timoshenko Beam Shear Deformation Deflection Calculator Formula & Variables

The core mathematical equation utilized by this calculator is expressed as:

\delta_{total} = \delta_b + \delta_s = \frac{P L^3}{48 E I} + \frac{P L}{4 \kappa A G}

Superposition of Euler bending compliance and Timoshenko transverse shear compliance.

How to Use the Timoshenko Beam Shear Deformation Deflection Calculator

  1. Enter beam span length and concentrated point load.
  2. Enter Young's modulus E, shear modulus G, moment of inertia I, and cross-section area A.
  3. Set shear correction factor kappa (default 5/6 for rectangular sections).

Step-by-Step Example Calculation

Heavy Machine Foundation Deep Steel Girder

Input Values:

spanLengthM:1
appliedPointLoadN:50000
elasticModulusEPa:200000000000
shearModulusGPa:80000000000
momentOfInertiaM4:0.00000833
crossSectionAreaM2:0.01
shearCorrectionFactorKappa:0.833
Worked Steps: Deep steel transfer beam supporting high concentrated industrial load.

Understanding Your Result

In slender beams (L/h > 20), shear deflection is under 1% of total deflection and can be neglected.

In deep beams (L/h < 5), shear deflection can contribute 15% to 40% of total deflection.

Factors That Affect the Result

  • Span-to-depth ratio (L/h): Shear deformation scales with (h/L)^2 relative to bending.
  • Cross-section shape: I-beams experience concentrated shear in the web, requiring kappa ~ A_web / A_total.

When Should You Use This Calculator?

  • Structural design of bridge pier transfer girders and foundation pile caps.
  • Fiber-reinforced composite laminates where shear modulus G is very low relative to axial modulus E.

Assumptions & Limitations

  • Applies to simply supported beam with center concentrated point load.
  • Assumes linear elastic material behavior.

Frequently Asked Questions

Calculation Accuracy & Reference Note

Standard Timoshenko beam solution universally implemented in structural FEA solvers.

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