The Frame4 spreadsheet is set up to allow the analysias of rigid-jointed 2D frames, but it is simple to use it for 2D truss analysis; simply either provide a moment release at each end of every member, or define every member with a second moment of area (I) sufficiently low that all bending moments will be negligible. I have added a truss example to the download zip file. The program has also had a minor upgrade to Ver 3.06. Free download (including open source code) from Frame4.zip.
The truss example is taken from: http://richardson.eng.ua.edu/Former_Courses/CE_331_fa00/Notes/Truss_Design_Example.pdf
The truss may either be specified with moment end releases at both ends of each member:
Or specify a very low I value for each member:
The results given in the example are shown below:
The axial load values from the spreadsheet are in good agreement:
Truss deflected shape:
Axial force in top and bottom chords: