Concrete Offshore platforms Gravity-Based str

Concrete Offshore platforms Gravity-Based structures - سکو های بتنی ثقلی

در این فایل انواع سکو های بتنی ثقلی ، روش نصب ، و موارد استفاده آنها توضیح داده شده است.

فایل pdf به زبان انگلیسی و حجم 14 مگ.

در زیر بخشی از این فایل آورده شده است :

 Offshore platforms of the gravity-base category are designed to be founded at or just below the seafloor, transferring their loads to the soil by means of shallow footings. Such gravity-base platforms have usually been constructed of reinforced and prestressed concrete but a few have been built of steel or a hybrid of concrete and steel. These  platforms  are  almost  always  constructed  in  their  vertical  (final)  attitude,  enabling  much  or  all of the deck girders and equipment to be installed at an inshore site and transported with the substructureto  the  installation  site.  These  structures  are  usually  self-floating,  although,  when  necessary,  additional lift forces may be developed by temporary buoyancy tanks or special lifting vessels. To  minimize  soil-bearing  loads,  these  structures  have  a  large  base  “footprint.”  To  provide  buoyancy, they  have  large  enclosed  volumes.  They  thus  generate  much  greater  inertial  forces  under  waves  and earthquake, 50,000 to 100,000 tons of lateral force being typical, with special structures developing even more Thus  sliding  tends  to  become  the  dominant  mode  of  failure,  at  least  for  water  depths  up  to  150 to 200 m.

To  transfer  this  lateral  load  into  the  soil  and  thus  prevent  sliding,  steel  skirts  and  steel  dowels  are
employed, designed to penetrate and thus force the failure surface farther below the seafloor. Such skirts
also  provide  protection  against  scour  and  piping.  While  the  skirts  are  typically  fixed  to  the  base  of  the
platform  during  fabrication,  in  special  cases  where  shallow  water  limits  draft,  skirts  or  spuds  may  be
installed  through  sleeves  after  the  structure  has  been  seated  on  the  seafloor.  A  typical  GBS  structure  is
shown in Figure 12.1.1 and 12.1.2
.