Shear and Bending Moment

ES 301 Assignment 3

Work Problem 7.36 in Beer and Johnston Statics, sixth edition in the usual way. Then, using either Notepad in Windows 95 or Emacs in Unix, write a Matlab program to find the shear and bending moment at the load points. Also, plot the bending moment vs. the distance along the beam as shown below. Run your program in Matlab. Be sure to program your name, date, and subject with lines such as:

    % print the results
    fprintf('\n   Beam with Concentrated Forces')
    fprintf('\n   Your name, ES 301, ')
Also, be sure to use 1x3 vectors for radius (r), force (f), shear (v) and moment (m):
    r = [ 0.6 (0.6+0.9) (0.6+0.9+1.5) ]
    f = [ ...
Find the reaction force B with r cross f using the Matlab expression
    sum( r .* f )
You can create the shear vector in a for loop with a vector expression. Print the results in a table with fprinf in a for loop.
   for i = 1:length(f)
     fprintf('  %2.0f  %6.0f  %6.1f  %6.1f \n',i,f(i),v(i),m(i))
Use the f format to control the number of displayed digits. Print the results with a heading in a table that starts like as:
           Force  Shear  Moment
            kN     kN     kN-M
             A     50.5    0
      1     40     10.5   30.3
      2     ...    ...    ...
      3     ...    ...    ...
Copy the output data from the screen and paste it into the bottom of your source program. Adjust the number between the % and . to align the decimal points. Print your source program with the appended output.

Make a plot of moment vs. distance with title, grid, and x and y labels using the plot, title, xlabel, ylabel, and grid commands. Since there will be five values of moment to plot, make two new vectors say m2 (1x5) and x2 (1x5) putting your original three moment and distance values in locations 2:4. Of course, the first and last moment values are zero. For example, try out these commands.

    m2 = zeros(1,5)       % make a 1x5 vector of zeros for m
    m2(2:4)=m(:)          % moments
Print the plot.

Staple the printouts of your source code and the plot to your solution obtained by the conventional method and turn it in as usual.


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Last revised: March 17, 2000