Free online beam calculator to draw bending moment diagrams, shear force diagrams, calculate reaction forces and measure deflection for an indeterminate beam span. This calculator can be used for structural analysis and beam analysis. Maximum bending moment can be calculated along with shear forces, reaction forces and deflection using steel section properties. Specify beam geometry and point loads or distributed loads to get started analysing the beam.

This code is open source and you can contribute to it's development.

You can find the source code on GitHub here: IndeterminateBeam

Special credits: Jesse Bonanno

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m

Steel section category:

Universal

Beams

Universal

Columns

European

Beams

European

Columns

American

Beams

SHS

(Square)

RHS

(Rectangle)

CHS

(Circle)

Select a steel section classification:

Section:

Moment of intertia

cm^{4}

Youngs modulus

GPa

Beam weight
kg/m

Check weight is > 0
Support number:

Point load number:

Position

mm

Magnitude

kN

Distributed load number:

From

mm

To

mm

kN/m

kN/m

When we apply a force somewhere along the span of a beam, we generate internal stresses. There are two types of stress which are generated:

**Normal stress:**Generated from forces act along the length of the beam in compression or tension.**Shear stress:**Generated from forces act parallel to the direction of the load.

The origin of these two stress components can be seperated into two force components we refer to as **Bending moment** and **Shear force**.

The simplest loads applied to a beam can be divided into three categories:

**Point loads:**This is a force applied to a single point on the beam.**Distributed loads:**This force is distributed over a certain length and acts as a form of pressure.**Concentrated moment:**This is a pure moment acting on a beam at a given position.

The simplest supports provided to a beam can be divided into three categories:

**Pinned support:**Restrain the beam in both horizontal and vertical directions without providing any restraint against rotation.**Roller support:**Support provided to the beam in only a single direction and no restraint against bending or rotation.**Fixed support:**These supports provide restraint to the beam in all directions and restrain against rotation.

To find the forces acting on a beam we must follow the process of creating a free body force diagram.

We first draw the beam to scale indicating the force components of the applied loads and then calculate the support reaction forces.

To calculate reactions we must use equilibrium equations to resolve the external forces:

**Ξ£ Vertical forces applied = 0kN****Ξ£ Horizontal forces applied = 0kN****Ξ£ Moments applied = 0kNm**

There are two types of cases when resolving beam external conditions:

**Statically determinate:**Where the number of equations is equal to the number of unknowns and the calculations can be solved using closed form hand calculations.**Statically indeterminate:**Where the number of unknowns exceeds the number of equations and more advanced methods such as Moment Resistribution Theory need to be used.

To create a shear force diagram you work from left to right across the beam summing the applied forces and reactions at each point they are applied. Cantilevers are the most straightforward example of this with a single reaction at one end of the beam span with zero shear force at the unsupported end.

To create a bending moment diagram you again must work from left to right across the beam and calculate the moment left of each point you are interested in.