Dynamic Analysis of Floating Bridges with Transverse Pontoons
The main objective of this thesis is to analyse the dynamic response of floating
bridges with transverse pontoons, when subjected to harmonic regular wave
loads. As a result, a simplified beam model of the Bergsøysundet floating bridge is
established in the FEM software Abaqus. Additional synthetic floating bridge
structures are subsequently built and analysed in a similar manner.
The pontoon model already developed in Genie by Abdillah Suyuthi is analysed in
HydroD to obtain the pontoons structural model and hydrodynamic parameters.
In addition to these parameters, by implementing his calculated data of mass and
sectional properties of the bridge truss-work components, the simplified beam
model of the bridge is developed in Abaqus. Taking the Bergsøysundet floating
bridge model as the basis, synthetic bridge models are similarly assembled and
studied. The effect of sideway mooring is also considered for some of the models.
Eigenfrequency analysis is then carried out in Abaqus in order to determine the
frequency of the fundamental mode of a model. The eigenfrequency and added
mass are updated by iteration until they are concurrent. Static and dynamic
analysis are then carried out for the model. The regular wave load corresponding
to the updated frequency of the mode is acquired from the hydrodynamic analysis
in HydroD and applied in Abaqus.
Efficient techniques are presented to calculate the phase difference at each
pontoon. This arises due to the combined effect of changing wave direction and
shapes of the models.
A simplified method is employed to gauge the critical angle of wave heading. The
effect of wave spreading is also assessed in a streamlined manner based on
discussion with the supervisor.
Limitations with regard to the non application of full matrices of the pontoons
structural model and hydrodynamic parameters are highlighted. Negatively
damped sway motions are controlled by the application of external lateral
dampers. Mixed results are obtained at the estimated critical angles. Better result
is obtained by iteration of the responses for growing angles of wave heading. The
wave spreading response result is satisfying
Place, publisher, year, edition, pages
Institutt for marin teknikk , 2014. , 107 p.
IdentifiersURN: urn:nbn:no:ntnu:diva-25640Local ID: ntnudaim:10810OAI: oai:DiVA.org:ntnu-25640DiVA: diva2:738204
Leira, Bernt Johan, Professor