Inplace Analysis, an Analysis in Fixed Offshore Platform

Hello World. We want to try to make blog regarding design and analysis for fix platform structure. we hope that a little paragraph which is the author is not experience well able to make understand readers.

In this post I'm only back link the previous post from my blog which i used to follow. However that blog in active anymore. Courtesy by Abang Lutfi Ramadhani as a good teacher. Please check for his blog.

In the design phase of a fixed offshore structure, in general there are two types of analysis, the analysis of in-service and pre-service analysis.

In-service analysis is to look at the failure mode analysis of fixed offshore platform structure at the time was operating / service. Basically, consisting of in-place analysis, fatigue analysis, and seismic analysis (if the platform in seismic regions). Three of this analysis which will determine the dominant structure configuration: Configuration member, joint, and material.

While Pre-service analysis is the analysis of fixed offshore structure at this stage of the installation and installation preparation, or in other words, before the platform is not operational yet . Analysis is needed include: lifting, load out, transportation, launching, upending, on-bottom stability, pile drivability. Pre-service analysis is not dominant in determining the configuration structure (except perhaps lifting and transportation analysis), due to the nature of the pre-service analysis is instantaneous, so it can be tricked, for example with a temporary member.

In-place analysis was first conducted analysis on fixed offshore structure. The aim is to ensure the structure withstand the loads during operation, both gravitational loads and environmental loads, and should be able to survive in extreme environmental condition.

His approach is a static analysis. Static analysis is an analysis of the current structure in a state of static / load silent. In fact, the environmental loads on a structure (eg wave) is the dynamic load moving / has acceleration, so the reality will exist the dynamic load due to the acceleration of the load. In my point of view, you could say something like this: wave loads were considered in the analysis is the wave 1 in-place annual and annual 100 which has a large wave period, so that when the structure, look like static. And also, because the great wave periods and periods of small natural structure, the dynamic load will be small. However, although the approach in-place analysis is a static analysis, we can consider the dynamic loads by adding dynamic amplification factor (DAF) on the load (considered) the static. In-place analysis generally consider the value of this DAF, and partly in-place analysis does not include the value of this DAF with the above considerations.

Generally, there are three conditions of in-place analysis, namely (1). Operating condition, which uses environmental burden: 1 year return period environmental; (2). Storm / extreme condition, which uses environmental burden: environmental return period of 100 years; and (3). Pullout condition, to see the pile tension minimum load capacity when gravitational and lateral loads (originating from environmental) maximum.

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