SOO20-7462(96)00033-9 RESPONSE OF A TWO DEGREES OF FREEDOM ARTICULATED TOWER TO DIFFERENT ENVIRONMENTAL CONDITIONS

Abstract-In a previous paper [J. Sound Vibr. (1996)], the response of an articulated tower in the ocean subjected to deterministic and random wave loading was investigated. The tower was modeled as an upright rigid pendulum with a concentrated mass at the top and having one angular degree of freedom about a hinge with coulomb damping. In this paper, which is an extension of the previous one, the tower is modeled as a spherical pendulum having two angular degrees of freedom. The tower is subjected to wave, current, vortex shedding, wind and Coriolis acceleration loads. Geometrical non-linearities as well as non-linearities due to wave drag force, which is assumed to be proportional to the square of the relative velocity between the tower and the waves, were considered. The governing coupled differential equations of motion are highly non-linear, and have time-dependent coefficients. The tower’s response to the external forces is found, that is, equilibrium position due to wind and current and response to wave excitation. Resonances (harmonic and subharmonic) and also chaotic response are investigated. Copyright 0 1996 Elsevier Science Ltd