BUNVIS-RG - Exact frame buckling and vibration program, with repetitive geometry and substructuring

Abstract

BUNVIS-RG is a computationally efficient FORTRAN 77 program which uses an exact stiffness matrix method to find the eigenvalues (i.e., critical load factors, or natural frequencies of vibration) and modes of three-dimensional frames without making the usual approximations of conventional finite element analyses. BUNVIS-RG includes: axially loaded Timoshenko or Bernoulli-Euler beams with distributed mass; taut strings; tapered and other nonuniform members; very efficient computation of modal densities; initial static calculations which include prestress and acceleration; dead and live load in buckling problems; rigid body modes; bandwidth reduction; treatment of stayed columns as substructures; treatment of linearly and rotationally periodic structures by analyzing a single repeating element; and elastic and offset connections between members and nodes. These and other features of BUNVIS-RG are described in this paper, which also gives results to illustrate its scope and efficiency and to establish a formula for predicting solution times.