Effective arrangement of hydraulic top bracing based on idealized load carrying mechanism

Hydraulic top bracing (HTB) has been widely used to control H-mode resonance of the main engine vibration system of large-sized commercial vessels. This paper provides procedures to effectively arrange the HTB for a 37,000 tonf deadweight class product carrier. The key point of this paper is that the operation mechanism of the HTB is idealized in terms of nonlinear stiffness components composed of three compressive and one tensile stiffness components. Frequency response analyses with different compressive stiffness (K3K3) at the static load stage reveal that K3K3 is a very important parameter for effective arrangement of the HTB. From time domain analyses, it is recognized that, as far as setting force is well controlled, two HTBs are sufficient to suppress H-mode excitation forces from the main engine. This paper concludes that stiffness K3K3 corresponding to the static load stage should be flexibly adjusted to absorb H-mode excitation, while higher stiffness K2K2 corresponding to the light load stage is necessary to detune the main engine vibration system.

► Procedure to effectively arrange the HTB is presented. ► The operation mechanism of the HTB is idealized. ► Compressive stiffness at the static load stage is an important parameter. ► Two HTBs are sufficient to suppress H-mode excitation forces.