Numerical Simulation of Submarine Pipelines In
22
EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS Earthquake Engng. Struct. Dyn. 27, 465— 486 (1998) NUMERICAL SIMULATION OF SUBMARINE PIPELINES IN DYNAMIC CONTACT WITH A MOVING SEABED C. KALLIONTZIS*R Computational Hydraulics O ffice, 70 Omirou Street, Nea Smyrni 17 121, Athens, Greece SUMMARY The dynamic response of submarine pipelines to earthquake-generated vertical seabed motions is examined with the aid of a finite element model. A relaxation algorithm is adopted in order to overcome the problem of unknown dynamic seabed reaction forces. Rotational rigidity is assumed at the boundary points, which are allowed to move vertically in unison with the random seabed oscillations. For the interior nodes, the description of the kinetic energy loss, resulting from pipeline— seabed impact, is approached through the use of a restitution coefficient of 0 )5, which represents an inte rmed iate collisio n mode between a perf ectl y elas tic and an inela stic one. Funda ment al system freq uenc ies are determined by the use of support positions obtained from a static analysis of the unilaterally constrained structure. The structural damping matrix is approximately evaluated according to Rayleigh’s method. Response spectra to a strong motion vertical acceleration earthquake record provide an initial guideline into the pipeline stability. Peak dynamic and static bending stresses are calculated for a case study involving two submarine pipeline crossings. Complete, partial and lack of pipeline gravel cover is assumed in the analysis. A seabed profile alteration, due to probable soil liquefaction, is furthermore imposed, in order to investigate the subsequent effect upon the dynamic pipeline stresses. 1998 John Wiley & Sons, Ltd. KEY WORDS: dynamic structural analysis; earthquake motion; finite elements; relaxation solution methods; submar ine pipelines; unilateral contact problems INTRODUCTION Submarine line structures, such as pipelines or cables, are nowadays routinely laid upon irregular seabed profiles. Identification of the random contact point distribution is of utmost importance in evaluating the peak bending stresses (pipelines) and the maximum suspensions (pipelines and cables). Since deformation takes place pre-domi nant ly along the vertical plan e, one-dimensional analy sis prov es suffici ent for the stability examination of the submarine structures. So far, the static analysis of unilaterally constrained systems has been the focal point of the majority of research. By transforming the random structure — soil contact problem into a linear complementary one, being equivalent to a strictly convex quadratic programming problem, Maier and Andreuzzi obtained solutions for the relative pipeline— seabed distances. Both elastic and piecewise linear elastoplastic deforma- tion laws were adopted in their model, which was used for obtaining the pipeline bending stresses along the Messina strait crossing. In a similar context, concerning submarine pipelines, the optimal control theory has also been emplo yed by Stavroula kis et al. and Chuan g and Smith. Bianc hi and Oliveri proposed a successive negative reaction node elimination method, capable of yielding the free span pipe lengths along any selected subsea route. Extensive experience of analysing several hundred kilometers of submarine pipe laying was reported. The precision of the bending stress predictions was mainly influenced by the level of * Correspondence to: C. Kalliontzis, Computational Hydraulics Office, 70 Omirou Street, Nea Smyrni 17 121, Athens, Greece R Civil Engineer, PhD CCC 0098— 8847/98/050465— 22$17)50 Received 14 November 1996 1998 John Wiley & Sons, Ltd. Revised 30 September 1997
-
Upload
bao-chunxiao -
Category
Documents
-
view
220 -
download
0
Transcript of Numerical Simulation of Submarine Pipelines In
8/6/2019 Numerical Simulation of Submarine Pipelines In
http://slidepdf.com/reader/full/numerical-simulation-of-submarine-pipelines-in 1/22
8/6/2019 Numerical Simulation of Submarine Pipelines In
http://slidepdf.com/reader/full/numerical-simulation-of-submarine-pipelines-in 2/22
8/6/2019 Numerical Simulation of Submarine Pipelines In
http://slidepdf.com/reader/full/numerical-simulation-of-submarine-pipelines-in 3/22
8/6/2019 Numerical Simulation of Submarine Pipelines In
http://slidepdf.com/reader/full/numerical-simulation-of-submarine-pipelines-in 4/22
8/6/2019 Numerical Simulation of Submarine Pipelines In
http://slidepdf.com/reader/full/numerical-simulation-of-submarine-pipelines-in 5/22
8/6/2019 Numerical Simulation of Submarine Pipelines In
http://slidepdf.com/reader/full/numerical-simulation-of-submarine-pipelines-in 6/22
8/6/2019 Numerical Simulation of Submarine Pipelines In
http://slidepdf.com/reader/full/numerical-simulation-of-submarine-pipelines-in 7/22
8/6/2019 Numerical Simulation of Submarine Pipelines In
http://slidepdf.com/reader/full/numerical-simulation-of-submarine-pipelines-in 8/22
8/6/2019 Numerical Simulation of Submarine Pipelines In
http://slidepdf.com/reader/full/numerical-simulation-of-submarine-pipelines-in 9/22
8/6/2019 Numerical Simulation of Submarine Pipelines In
http://slidepdf.com/reader/full/numerical-simulation-of-submarine-pipelines-in 10/22
8/6/2019 Numerical Simulation of Submarine Pipelines In
http://slidepdf.com/reader/full/numerical-simulation-of-submarine-pipelines-in 11/22
8/6/2019 Numerical Simulation of Submarine Pipelines In
http://slidepdf.com/reader/full/numerical-simulation-of-submarine-pipelines-in 12/22
8/6/2019 Numerical Simulation of Submarine Pipelines In
http://slidepdf.com/reader/full/numerical-simulation-of-submarine-pipelines-in 13/22
8/6/2019 Numerical Simulation of Submarine Pipelines In
http://slidepdf.com/reader/full/numerical-simulation-of-submarine-pipelines-in 14/22
8/6/2019 Numerical Simulation of Submarine Pipelines In
http://slidepdf.com/reader/full/numerical-simulation-of-submarine-pipelines-in 15/22
8/6/2019 Numerical Simulation of Submarine Pipelines In
http://slidepdf.com/reader/full/numerical-simulation-of-submarine-pipelines-in 16/22
8/6/2019 Numerical Simulation of Submarine Pipelines In
http://slidepdf.com/reader/full/numerical-simulation-of-submarine-pipelines-in 17/22
8/6/2019 Numerical Simulation of Submarine Pipelines In
http://slidepdf.com/reader/full/numerical-simulation-of-submarine-pipelines-in 18/22
8/6/2019 Numerical Simulation of Submarine Pipelines In
http://slidepdf.com/reader/full/numerical-simulation-of-submarine-pipelines-in 19/22
8/6/2019 Numerical Simulation of Submarine Pipelines In
http://slidepdf.com/reader/full/numerical-simulation-of-submarine-pipelines-in 20/22
8/6/2019 Numerical Simulation of Submarine Pipelines In
http://slidepdf.com/reader/full/numerical-simulation-of-submarine-pipelines-in 21/22
8/6/2019 Numerical Simulation of Submarine Pipelines In
http://slidepdf.com/reader/full/numerical-simulation-of-submarine-pipelines-in 22/22
