## Shear Force Bending Moment

version 3.7.0 (771 KB) by
Lateef Adewale Kareem

This function SFBM.m calculates and draw the shear force and bending moment diagrams.

**Editor's Note:** This file was selected as MATLAB Central Pick of the Week

This file explains how to use the SFBM.m code. as well as supporting

accessories. SFBM means Shear Force & Bending Moment.

This program calculates the shear force and bending moment profiles, draw

the free body, shear force and bending moment diagrams of the problem.

Under the free body diagram, the equations of each section is clearly

written with Latex

To use this program, you call the function placing the arguments in cells

with keywords at the beginning of each cell except for the first 2 arguments.

First Argument

The first argument is the name of the problem as a string e.g.: 'PROB 1'.

Second Argument

-Simply supported beam

The second argument is a row vector containing length of the beam and

location of the supports, for example, if the length of the beam is 20m and

has 2 supports, one at 3m and the other at 17m, the second argument will

thus be: [20, 3, 17]

-Cantilever

If the problem is a cantilever problem, then you have only one clamped

support, at the beginning or end of the beam. In such a case, the number is

second argument contains 2 elements instead of three. For instance, fir a

cantilever of length 20m, supported at the beginning, the second argument

would be [20,0], and if supported at the end, we have [20,20].

-Beam on the floor

Its possible to have a problem in which the body is lying on the floor

without any point support. In such scenario, the second argument will just

be the length of the beam

Third argument and on

From the third argument and onward, we use cells. The first element of the

cell contains a keyword describing what type of load is inside the argument.

The second element is the magnitude of the load while, the third element of

a cell argument is its location.

Keywords: Point Load = 'CF'

Moment = 'M'

Distributed Load = 'DF'

To add a downward point load of magnitude 5N at location 4m, the argument

would be {'CF',-5,4}. Note the negative sign. If the force is acting upward

the argument would be {'CF',5,4};

To add a clockwise moment of magnitude 10N-m at location 14m, the argument

would be {'M',-10,14}. Note the negative sign. If the moment is anticlockwise

the argument would be {'M',10,14};

To add distributed load we need to describe all of them with the minimum

number of point required to describe the profile with the highest

complexity. For example, a linear profile can be described as {'DF',[5,5],[2,10]}

meaning uniform force per unit length of 5N/m from point 2m to 10m. If the

values of the profile were given at 3 points, the code will automatically

assume it to be quadratic. If profile is uniform, the coefficient of the

second and first degrees would be zero.Hence describing the constant 5N/m

from 2m to 10m as {'DF',5,[2,10]}, {'DF',[5,5],[2,10]}, {'DF',[5,5,5],[2,8,10]}

will make no difference. But in case where the values in the force vector

are different, SFBM will generate a polynomial fit for the forces as a

function of position. For instance {'DF',[1,5,5],[2,8,10]} will generate a

quadratic function, while {'DF',[1,4,5],[2,8,10]} will generate a linear

expression and {'DF',[5,5,5],[2,8,10]}will generate a degree zero expression

There is no limit to the number degree of polynomial that can be used.

its is important that all concentrated loads and torques are listed in the

order of locations

For example:

SFBM('Prob 200',[20,5,20],{'CF',-2,0},{'M',10,8},{'DF',5,[1,3]},{'M',-10,12},{'DF',-4,[14,17]})

Name : Prob 200

Length: 20m

Supports: 5m and 20m

Point Load: 2N at point 0

Distributed Load: Constant 5N/m from 1m to 3m and Constant -4N/m from 14m to 17m

Moment: ACW 10Nm at point 8m and CW 10Nm at point 12

Solution:

The Freebody (with Legend), Shear Force and Bending moment diagrams are generated and saved in picture format titles Prob 200.png.

### Cite As

Lateef Adewale Kareem (2022). Shear Force Bending Moment (https://www.mathworks.com/matlabcentral/fileexchange/51047-shear-force-bending-moment), MATLAB Central File Exchange. Retrieved .

##### MATLAB Release Compatibility

Created with
R2013b

Compatible with any release

##### Platform Compatibility

Windows macOS Linux##### Categories

##### Tags

##### Acknowledgements

**Inspired:**
Shear, moment, and hinge for Statically Determinate Beams

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