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Go to Editorial ManagerThis study investigates the vibration behavior of cantilever beams with bolted joints of different lap types (single lap and double lap) under free and forced vibration conditions. The effects of various parameters, including beam configuration, bolt preload, harmonic force magnitude, and force application position, on natural frequency, mode shape, and vibration amplitude are analyzed. Experimental work involved material selection, chemical composition testing, tension tests, beam preparation, and free and forced vibration tests with pre-torque ranging from 6 to 60 N·m and rotational speeds between 300 and 900 RPM. Numerical simulations were performed using the general-purpose finite element software ANSYS 16.1. Results indicate that the natural frequencies of single-lap bolted beams (1 or 2 bolts) are approximately equal to those of intact beams, while double-lap bolted beams exhibit slightly lower natural frequencies than intact beams with the same profile. Increasing bolt preload stabilizes the natural frequency for all beam configurations. For forced vibrations, the amplitude is strongly influenced by the magnitude and position of the applied harmonic force. Validation with experimental results shows good agreement, with a maximum error of approximately 5%.
In the present study, the dynamic analysis of jacket type offshore structures under the action of sea waves is carried out. The finite element method is adopted for the solution of the problem. The effect of soil-structure interaction on the dynamic behavior of the offshore structure is taken into account due to the deformations of the soil caused by the motion of the structure, which in turn modify the response of the structure. The supporting elastic foundation is represented by Winkler type model having normal and tangential moduli of subgrade reaction. These moduli may be constant or varying linearly or nonlinearly along the embedded length of the piles that support the offshore structure. The pile tip conditions are also considered. A time domain solution is recommended. The generalized Morison's equation is used to calculate the wave forces and Airy's linear theory to describe the flow characteristics. Both free and forced vibration analyses are studied. The dynamic response has been obtained by modal analysis in conjunction with Wilson-0 method. As an example, a modified model of an actual jacket type offshore platform is analyzed under the action of wave forces.
In the present study, the dynamic analysis of jacket type offshore structures under the action of sea waves is carried out. The finite element method is adopted for the solution of the problem. The effect of soil-structure interaction on the dynamic behavior of the offshore structure is taken into account due to the deformations of the soil caused by the motion of the structure, which in turn modify the response of the structure. The supporting elastic foundation is represented by Winkler type model having normal and tangential moduli of subgrade reaction. These moduli may be constant or varying linearly or nonlinearly along the embedded length of the piles that support the offshore structure. The pile tip conditions are also considered. A time domain solution is recommended. The generalized Morison's equation is used to calculate the wave forces and Airy's linear theory to describe the flow characteristics. Both free and forced vibration analyses are studied. The dynamic response has been obtained by modal analysis in conjunction with Wilson-θ method. As an example, a modified model of an actual jacket type offshore platform is analyzed under the action of wave forces.