Non-Linear Analysis of an Integral Bridge

Spar platforms are treated as cost-effective and resourceful type of offshore structure in deep water. With increasing depth there are significant changes in its structural behaviour due to coupling of spar hull-mooring line along with radical influence of mooring line damping. So these phenomena should be precisely counted for accurate motion analysis of spar mooring system. In present study, spar platform are configured as a single fully coupled integrated model in ABAQUS/AQUA. Non-linear dynamic analysis in time domain is performed adopting Newmark-β automatic time incrementation technique. Non-linearities due to geometric, loading and boundary conditions are duly considered. Displacement and rotational responses of spar and mooring tensions are obtained during long-duration storm. spar responses get significantly modified and mean position of oscillations gets shifted after longer wave loading. The surge, heave and pitch responses are predominantly excited respectively. The energy contents of PSDs of these responses reduce considerably after long wave loading. Mooring tension responses are significantly different reflecting the damping effect of mooring lines. The pitch response is fairly sensitive to the wave loading duration. After long duration of storm the wave frequency response increases. However, low frequency and wave frequency responses may simultaneously occur due to synchronising sea states.

Section: Introductionmentioning

confidence: 99%

Non-Linear Dynamic Analysis of Coupled Spar Platform

Jameel

Ahmad

Islam

et al. 2013

“…In spite of a lot of numerical and experimental works in passive pressure evaluation, the behaviour of this type of bridges has not already been well defined (Dicleli, Erhan 2010;Erhan, Dicleli 2009;Fang et al 1994Fang et al , 2002Fang, Ishibashi 1986;James, Bransby 1970;Kim, Laman 2010b;Noorzaei et al 2010).…”

Section: Fig 2 a Schematic View Of Integral Bridges Abutmentmentioning

confidence: 97%

An Investigation on the Effect of Cyclic Displacement on the Integral Bridge Abutment

Movahedifar

Bolouri-Bazaz

2014

The integral bridge abutment, as a special type of retaining wall, is subject to cyclic displacement, which is due to the daily and seasonal temperature variations. The frame of this type of bridges is rigid and jointless. This requires that the slab of the bridge to be longitudinally continuous without expansion joints. This causes cyclic displacement to be imposed to the backfill material of integral bridge abutment. It should be pointed out that the omission of expansion joints helps to provide a fluent traffic and a reduction in maintenance and repair of the bridges. To investigate the impact of cyclic displacement on the loose backfill soil behaviour, an innovative laboratory retaining wall model has been designed and constructed to imitate the cyclic behaviour of backfill granular material. In addition, a numerical model, based on finite element method, has been developed to interpret the experimental results. This model was calibrated using the laboratory test data. The results indicate that the passive pressure, except for low amplitude displacement, escalates with progressive number of cycles and its distribution is not linear, which is due to the forming arch.

“…Ma and Patel (2001) have conducted parametric studies on Spar and TLP for different depths. Sarkar and Roesset (2004), Grigorenko and Yaremchenko (2009), Kim and Lee (2011), Noorzaei et al (2010) carried out static as well as dynamic analysis for differ-ent environmental conditions and evaluated the response behaviour. Low and Langley (2007) have compared the methods for the couple analysis of floating structures.…”

Section: Introductionmentioning

confidence: 99%

Structural Behaviour of Fully Coupled Spar–mooring System Under Extreme Wave Loading

Islam

Jameel

Ahmad

et al. 2014

Floating spar platform has been proven to be an economical and efficient type of offshore oil and gas exploration structure in deep and ultra-deep seas. Associated nonlinearities, coupled action, damping effect and extreme sea environments may modify its structural responses. In this study, fully coupled spar-mooring system is modelled integrating mooring lines with the cylindrical spar hull. Rigid beam element simulates large cylindrical spar hull and catenary mooring lines are configured by hybrid beam elements. Nonlinear finite element analysis is performed under extreme wave loading at severe deep sea. Morison's equation has been used to calculate the wave forces. Spar responses and mooring line tensions have been evaluated. Though the maximum mooring line tensions are larger at severe sea-state, it becomes regular after one hour of wave loading. The response time histories in surge, heave, pitch and the maximum mooring tension gradually decreases even after attaining steady state. It is because of damping due to heavier and longer mooring lines in coupled spar-mooring system under deep water conditions. The relatively lesser values of response time histories in surge, heave, pitch and the maximum mooring tension under extreme wave loading shows the suitability of a spar platform for deep water harsh and uncertain environmental conditions. Reference to this paper should be made as follows: Islam, A. B. M. S.; Jameel, M.; Ahmad, S.; Jumaat, M. Z.; Kurian, V. J. 2013. Structural behaviour of fully coupled spar-mooring system under extreme wave loading, Journal of Civil Engineering and Management 19(Supplement 1): S69-S77. http://dx.Mohammed JAMEEL did his PhD at Indian Institute of Technology Delhi (IIT Delhi), India. He has successfully completed various sponsored projects involving nonlinear analysis of TLPs, Spar, FPSO platforms, deep and shallow water mooring lines and Risers. The projects were supported by several government and private funding agencies. Presently he is associated with Department of Civil Engineering, University of Malaya, Malaysia. His research area includes Non-linear Dynamics, Earthquake engineering, Reliability engineering, Offshore structures, Artificial neural network and Nonlinear finite element analysis.