Risk Assessment & Management Based Hurricane Wave Criteria for Design and Requalification of Platforms in the Bay of Campeche

Abstract

This peper wes selected for presentation by the OTC Program Commillee following review of informetion oontained in en ebstrect subm~ted by the euthor(s). Contents of the peper, as presented, heve not been reviewed by the Offshore Technology Conference end are subject to correction by the euthor(s). The materiel, as presented, does not necessarily reflect eny position of the OffShore Technology Conference or its officers. Electronic reproduction, distribution, or storage of eny part of this peper for commerciel purposes without the wr~ten oonsent of the OffshOre Technology Conference is prohib~ed. Permission to reproduce in print is restricted to en ebstrect of not more than 300 words; illustrations may not be oopied. The abstrect must contain oonspicuous acknowledgment of where and by whom the paper was presented.85 and characterizations associated with interactions of the hurricane waves with the soft sea floor soils, wave-in-deck forces, the capacities of new, damaged, and repaired tubular joints, the fatigue of tubular joints and appurtenances, and the stiffness and capacities of laterally and axially loaded piles. Working Stress Design (WSD), Load and Resistance Factor Design (LRFD), and Ultimate Limit State (ULS) platform design and requalification guidelines were developed. This paper summarizes the guidelines that were developed for hurricane ULS and WSD evaluations. This study could not have been performed, completed, or have probed as deeply as it did into the multitude of important issues without the assistance, encouragement, and advice of IMP engineering team including

Developments in Proposed ISO Guidelines for Design of Offshore Platforms to Resist Earthquakes

“…At an average return period of 10,000 years, the indicated peak horizontal ground acceleration (Am) is indicated to be Am • 0.25 g. Table 1 summarizes the ground motions at return periods of 200 and 4000 years and the uncertainties (natural or Type 1, aleatory) associated with the ground motions (expressed as the standard deviation of the logarithms of expected annual G, σ lSE ). 20 These results can be compared with those developed by Guerra and Esteva 18 for the Bay of Campeche and firm alluvium sites. At a return period of 100 years, the peak horizontal ground acceleration obtained by Guerra and Esteva is G = 6.6 % g. This compares with a maximum value of G = 5.0 % g obtained by Chavez for a 100 year return period for the Zone 2 sources.…”

“…For mat supported structures that receive the majority of their input motions from soils that are located near the sea floor, this can be an important consideration. 27,28 For vertically incident earthquake compression waves, the ratio of the reflected to the incident wave amplitude at the ground surface is a function of the impedance ratio, IR, at the ground surface: 29 (20) where ρ is the mass density of the soil (s) and air (a), and V is the compression wave velocity in the two media. On land, this impedance ratio is very large, and one would expect almost total reflection of the energy at the ground surface.…”