DYNAMIC ANALYSIS OF THIN-WALLED AND VARIABLE OPEN SECTION BEAMS WITH SHEAR FLEXIBILITY

The equations of motion of thin-walled beams with open cross-section, considering the effects of shear flexibility and rotatory inertia in t he stress resultants, as well as variable cross-sectional properties a re presented using a state variables approach. These equations are bas ed on Vlasov's theory of thin-walled beams, which is modified to inclu de the effects indicated above. The resulting equations are used in th e determination of the natural frequencies of an open cross-section pr estressed concrete beam. Comparisons with other formulations are also presented employing the waves dispersion equation.