Structural Engineering

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After getting some sufficient results from petroleum engineering side (drilling and reservoir engineer), process engineer will directly coordinate other disciplines in designing offshore fixed platform accordingly. They concern of substantial oil and gas which convert to the further processes. In accomplishing the best approach, they will be supported by structural, piping, mechanical, electrical, and instrument engineer for technical assessments. Having discussed final decision, structural engineers will have the big responsibility of platform structure strength during its lifetime service. However, another part should continually have the similar portion for maintenance intension. Therefore, green field project or brown filed project is going to require them as an expert for solving engineering problems.

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Structural Engineering is a Civil Engineering part which concern about design, construction, and installation of building/structure by using appropriate material in withstanding certain loads/forces during its lifetime. By studying the specific area, different kind of structures can be built properly in different locations. Bridge, flyover, high risk building, damn, jetty, offshore platform, retaining wall, airport, and port are the products of structural engineering that provide more benefit for the particular purposes. Mainly, structural engineer have the authority and responsibility of structural integrity. They are supposed to be a problem solver by utilizing their skills to accomplish each structural subject matter.

Similar to the dry land structures, offshore platforms are also emphasizing gravity, earthquake, and environmental wind load as engineering evaluation. However, environmental load such as wave and current should be estimated correctly. In order to ensure the ability of structure, structural mechanic and wave engineering are the key basic concepts in elaborating obvious analyses.

In referring to structural engineering curriculum which is being organized by university, some subjects of structural mandatory are presented below. A reference book of each subject is also given.

Study Subject Refrence Book
Statics “Engineering Mechanics, Statics”, by R. C. Hibbeler
Strength of Materials “Mechanics of Materials”, James M. Gere and Barry J. Goodno
Structural Analysis “Structural Analysis”, by R. C. Hibbeler
Steel Structures “Steel Structures: Design and Behavior”, by Charles G. Salmon, John E. Johnson, and Faris A. Malhas
Structural Dynamic and Introduction to Earthquake Engineering “Structural Dynamics, Theory and Computation”, by Mario Paz and William Leigh and “Fundamental Concepts of Earthquake Engineering”, by Roberto Villaverde
Foundation Engineering “Principles of Foundation Engineering”, by Braja M. Das
Water Wave Mechanics “Water Wave Mechanics for Engineers and Scientists”, by Robert G. Dean and Robert A. Dalrymple
Offshore Structure “Handbook of Offshore Engineering, Volume I”, by Subrata K. Chakrabarti
Finite Elements Analysis “The Finite Element Method: Linier Static and Dynamic Finite Element Analysis”, by Thomas J. R. Hughes

Structural considerations have a lot of analyses to be performed in specific consequences. In general, there are two main attentions that will be used to assess structure for withstanding particular load in different analyses such as in-service and pre-service analysis. In-service analysis can be defined as condition while structural platform is standing for its lifetime. On the other hand, construction and installation condition are involved as pre-service condition.

According to the common practices, those analyses could be broken down below.

In-service Analysis
• Inplace Analysis
• Seismic/Earthquake Analysis
• Fatigue Analysis
• Collision Impact Analysis

Pre-service Analysis
• Lifting Analysis including Rigging Aids Design
• Transportation Analysis including Seafastening Design
• Load-out Analysis
• Launch Analysis
• Up-ending Analysis
• Floating Analysis
• Jacket on Bottom Stability Analysis
• Pile Drive Ability Analysis
• Pile Stick-up Analysis

Some software can be implemented by structural engineering for supporting their engineering judgment. Mostly, almost all structural software will be useful for making structural configuration and computation results. However, SACS Software is very user friendly since the wave and current load are able to be thoroughly generated. As a product of Bentley software, SACS modules have been gradually improving by following offshore industry development.

Basically, global analyses could be performed by using software. Furthermore, miscellaneous calculations are the best approach for those which aren’t able to be done in generating structural computer program. Instead of using software, some spread sheets are usually evolved such as mathcad and excel sheet.

In referring to some necessaries and experiences, miscellaneous calculations are focused on the following concerns, for instances.
• Weld and Bolt Connection Design
• Plate and Grating Design
• Dropped Object Check
• Clamp Design
• Monorail Design
• Stubbing Guide Design
• Vortex Induced vibration (VIV) Check
• Padeye Design
• Rigging Design
• Sea-fastening Design
• Anode Calculation
• Member Strengthening Check
• CD and CM Calculation
• Conductor Added Mass Calculation
• Density of Riser Calculation
• Density of Boat-landing Calculation
• Conductor Shielding Factor Calculation
• Crane Pedestal Load Calculation
• Wave Slam Analysis
• Weight Control Report and/or Material Take Off
• To be updated

Designing, installation, construction, and fabrication should be correctly experienced based on appropriate code and standard which are API RP2A WSD/LRFD, AISC, DNV, and/or local provision are mainly used. Sometimes, company specifications would be definitely followed as additional rules. Both of them will be supposed to combine as design basis that can be guided to start working. For foundation needs, soil survey should be done for identifying the characteristic of soil layer. Geotechnical engineer is supposed to devise the fundamental pile after discussing with structural engineer in term of structural behavior.

On the final stage, strength and safe structure should be hopefully enjoyed while the construction and installation have been completed. It can be concluded that other disciplines will certainly execute their duty for operating platform as the oil and gas principal purposes.

© BNK

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Posted on May 22, 2014, in Structural. Bookmark the permalink. Leave a comment.

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