The educational version of RISA-2D, a computer program developed by RISA Technologies
for use with Fundamentals of Structural Analysis by Leet and Uang, is a first-order,
interactive computer program for the analysis of two-dimensional (planar) structures,
such as beams, trusses, and frames. RISA-2D was developed to make the definition,
solution, and modification of two-dimensional determinate or indeterminate structural
problems simple and fast. The program allows you to draw and edit a model of
the structure on the computer screen. The final results--reactions, axial force,
shear, and moment diagrams, as well as the deflected shape--can be displayed
graphically. This student version, limited to structures with a maximum of 50
joints and 50 members, will permit you to analyze the majority of problems in
a basic course in structural analysis.
A first-order analysis assumes that joint displacements are small enough so
that a valid analysis can be based on the initial geometry of the structure.
Since the program does not account for the effect of additional forces and deflections
produced by large joint displacements, forces and deflections of slender members
carrying compression or compression and moment (such as long slender arches
or columns in rigid frames) may be underestimated significantly.
The computer solution is based on the direct stiffness method covered in Chapters
16, 17, and 18 of the textbook. In this procedure the stiffness of each element
of the structure is calculated. These stiffnesses are then combined to produce
the global stiffness matrix of the structure. The global stiffness matrix is
solved for the applied loads to calculate joint deflections, which in turn are
used to calculate the individual element forces and deflections.