02936nas a2200241 a 450000500170000000800410001703500150005810000270007324500750010026000670017530000200024249000280026250001830029050200580047352018240053165000390235570000370239470000510243170000470248271000390252981000600256885600660262820260817163127.0110303s2010    th uu|m rtt   0|  a1eng d  a.b120911700 aWitcha Leepipatpaiboon13aAn appropriate fea modeling technique for on-bottom roughness analysis  aPathum Thani, Thailand :bAsian Institute of Technology,c2010  a197 p. :billl.1 aThesis ;vno. OTM-10-06  aA thesis submitted in partial fulfillment of the requirements for the  degree of Master of Engineering in Offshore Technology and Management, School of Engineering and Technology  aThesis (M.Eng.) - Asian Institute of Technology, 2010  aPipeline  spanning  analysis  is  the  one  of  critical  criteria  for  pipeline  design.  An  evaluation  of  an  allowable  free-span  length  is  required  in  pipeline  design.  However,  the  possible  free  span  for  checking  against  the  allowable  limit  is  important  as  the  free  span  is  the  unknown  value  until pipeline already laid. The pipeline will suffer in the buckling effect and overstress if the free span is exceed than the allowable length. On-bottom roughness analysis is a name of computer simulation using for finding the pipeline configuration  on  the  seabed.  The  simulation  is  taken  care  by  ABAQUS  program.  The  simulation  results  depend  on  several  parameters  including  (i)  Analysis  boundary  conditions,  (ii)  Type  of  elements,  (iii)  Soil  modeling  technique  and  (iv)  Environmental  modeling  technique. Variation of these parameters leads to significant divergence of simulation results. The  appropriate  parameters  shall  be  selected  to  ensure  the  simulation  result  is  realistic.  This  study  is  to  determine  the  appropriate  finite  element  modeling  technique  for  on-bottom  roughness analysis. Three parameters including (i) Analysis boundary conditions, (ii) Type of elements, (iii) Soil modeling technique, were selected as variable in analysis. The appropriate model will be selected by degree of span accuracy, degree of conservative model and suitably run-time and resource. The appropriate model should be accurate and conservative in time and resource limitation. The boundary condition 1 and 4 are the appropriate models especially boundary condition which uses less time and resource for analysis. B33H element is conservative in the pipeline spanning while PIPE31H element is conservative in maximum von mise stress.   0aPipelinesxDesign and construction1 aChiu, Gregory L.F.,eChairperson0 aPornpong Asavadorndeja,eExamination committee0 aPennung Warnitchai,eExamination Committee2 aRTG Fellowship,eScholarship donor2 aAsian Institute of Technology.tThesis ;vno. OTM-10-06  3Full-Textuhttp://203.159.5.9/ait-thesis/detail.php?q=B03605