bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Procedure for Predicting the Fatigue Damage of Structural Members in Unsteady Winds
Authors: Vandiver J. Kim , Fei Chen Yang , Campbell R. Brad , Rudge Daniel 
Published: October 2008

Abstract
The practice of assuming fill, steady state, vortex-induced vibration response, to wind is excessively conservative [1]. This paper presents a practical methodfor estimating the reduction of the fatigue damage rate due to the naturalunsteady fluctuations in wind speed. Two dimensionless parameters are shown tobe particularly important. The first is the ratio of the lock-in bandwidth tothe turbulence intensity level of the wind. The second is the ratio of thelength of time the wind speed remains in the lock-in interval to the rise timeof the member to steady state response levels. The paper also shows that onemust account for the discrete nature of wind speed and direction scatterdiagrams in estimating the probability of occurrence of the critical windspeed.

Introduction
A 1992 review [2] of state-of-the-art design calculations for wind-inducedfatigue damage of structural members revealed substantial excess conservatismdue to the assumption of steady state structural response to wind. Further workwas recommended to establish the effect of unsteady wind speed variations, turbulence, and finite structural response rise time. These factors have nowbeen investigated by means of wind tunnel tests, analysis of extensive NorthSea wind records, and development of appropriate dynamic and probabilisticmodels.
The theoretical results, wind tunnel data, and statistical analysis of the winddata have been published in two recent papers and a Ph.D. thesis [3, 4 &5]. This paper synthesizes these results in the form of a proposed, practicalprocedure for predicting the fatigue life of structural members excited byvortex shedding in wind.
In this paper the members are assumed to vibrate in the first mode in thecross-flow direction. The only types of members studied are restrained at bothends, with boundary conditions which may vary from pinned to fixed. Otherstructural configurations such as cantilevers could be addressed by the methodsdescribed here, but no emphasis has been given to such applications in thisstudy.

Assumptions, Definitions and Objectives
Accepted practice in the industry today is to compute D,,, the steady statefatigue damage rate that results from wind at the critical wind speed, V,, which causes maximum vibration response. This damage rate is then multiplied bythe fraction of the year that the wind is expected to blow at or near to thecritical velocity for that member. [n this paper three adjustment factors, YoY1 and Y1introduced, so as to obtain theadjusted damage rate, D,, as shown below,
(MATHEMATICAL EQUATION AVAILABLE IN FULL PAPER)
The first two factors, Y0 and Y1, account forthe unsteady behavior of natural winds and the finite rise time required by thestructural member to reach steady state, given the wind is at the critical windspeed. The third correction factor, Ybin, accounts for the use ofdiscrete wind speed and direction scatter diagrams rather than smooth windspeed probability density functions.
The Heidrun Field - Development Overview
Authors: Mitcha J.L. , Morrison C.E. , de Oliveira J.G. 
Published: October 2008

ABSTRACT
Heidrun an oil and gas field lying in 345 meters of water off the coast of Norway. has been developed using the world's first concrete Tension Leg Platform (TLP). The TLP substructure. comprised of the Hull and Module Support Beams (MSB'S) is built of high strength lightweight aggregate concrete. The MSB concept eliminated the need for a module support frame and enabled the modules to be mated will the SUbStIUCIUI＿Cby ballasting and de ballasting, without the use of expensive heavy Lift vessels. The TLP topsides consists of five main modules and a drilling rig. The design concept of these large modules as self contained elements enabled them to be pre-commissioned to a Large extent at the fabrication yards, prior to load out. Sixteen tubular steel Tethers anchor the platform to four concrete Foundations on the seabed. These Foundations were towed to the field and Lowered into position by ballasting. again without the use of heavy lift vessels. Installation of a sub sea Well Template enabled the first wells to be pre-drilled and pre-completed before the platform was towed to the field. enabling an early production start after platform instillation. TIVO oil export pipe-Lines and one gas export line were completed onshore then MCI towed to the field using the controlled depth tow method. Titanium is used for the platform Drilling Riser, providing the same strength as conventional materials but with considerable weight savings. Produced oil from Heidrun is offloaded directly into shut ankles, without intermediate storage, using the innovative Submerged Turret Loading technology.

THE HElDRUN FIELD
Introduction. This paper first describes the main parameters of the field and the phases of the project development from discovery to first oil. The main components of the platform, sub sea development and export system arc described. The project organization is outlined. A description of the pre-operations drilling program is given. Construction of the concrete hull, fabrication of the topsides modules and marine operations. including module transportation and platform installation, arc reviewed. Emphasis is placed upon the novel aspects ofthc field development.
Field Location and Environment, Heidrun, which is an oil field with associated gas and gas cap, is located under the stormy waters of the Norwegian Sea, 175 kilometers from the coast. and covers an area of 38 square kilometers (9,000 acres). Water depth at the field is 345 meters. Fig. 1 shows the field location.
Discovery. The License for Conoco to explore and appraise the Heidrun field was awarded in 1984 and the first WCII was drilled in August of that year. The first well was a dry hole but the second WCII. completed in June 1985. encountered a 137 meler oil column in the Lower Jurassic Tile Formation, In addition. the upper part of the Tile Formation and the Middle Jurassic Fangst Group were found to be gas bearing, Seven more wells drilled on the block to confirm and delineate the field. Flow rates from the tests merged up to 930 m3 (6,000 barrels) per day.
Seismic Exposure and Site Response Characteristics for Offshore Platform Design
Authors: Grouse C.B. 
Published: October 2008

Abstract
Members of Panel 5 (P5) of the International Standards Organization (ISO) Working Group 3 (WG3) have developed earthquake design criteria for inclusion in 1S0's design guidelines for fixed offshore platforms. One of the components of these criteria was a procedure to determine the shape and level of the elastic design spectrum to be used in the computation of the design earthquake loads. The shape of the spectrum depends not only on the local geology at the platform site but also on the seismotectonic zone of the site region. The level of the spectrum depends on the seventy of the ground-motion seismic hazard.

Introduction
Various working groups and technical panels under the 1S0 have been working during the last several years to develop guidelines for the design of fixed offshore platforms worldwide. Several panels were convened to address aspects of earthquake resistant design including:seismic exposure and site response characteristics,structural and foundation design considerations,operation and performance issues, andprobability based earthquake load and resistance factor design concepts.
The members of WG3/P5 were responsible for developing the earthquake loading and response criteria within the framework of the Load and Resistance Factor Design (LRFD) approach, which has also been incorporated into the API RP2A guidelines for fixed offshore platform design.' A summary of the earthquake LRFD guidelines developed for the initial edition of the 1S() guidelines can befound in a paper by Bea3, published in these proceedings. A necessary component of the earthquake guidelines was the determination of the earthquake loads, which involved specification of elastic designs spectra. The procedure to specify the spectra is the subject of this paper.

Background
A primary ingredient in earthquake resistant design of offshore platforms is the specification of elastic design spectra that are used to calculate the earthquake loads. In the API RP2A guidelines' a simple procedure is provided to obtain these spectra in lieu of a site-specific study. According to these guidelines, the only parameters required to obtain the 5% damped elastic design spectrum for a particular offshore site are the local soil type at the site and the seismic zone in which the site is located. The local soil types in the API RP2A guidelines are (1) bedrock (Soil Type A), (2) shallow stiff soil (Soil Type B), and (3) deep stiff soil (Soil Type C). A site dependent spectral shape is presented in the API RP2A guidelines for each of these soil type. Seismic zonation maps for the offshore areas of the United States are also provided in these guidelines. Zones are designated as O, 1, 2, 3, 4, or 5, where Zone O represents negligible seismic hazard (e.g. Gulfof Mexico) and Zone 5 represents the highest seismic hazard (e.g. Gulf of Alaska). The API RP2A guidelines provide a table listing the ground accelerations for these zones, which range from O(Zone O) to 0.40g (Zone 5) in uneven increments.
Region and Site Specific Design Guidelines for the Northeastern Venezuela Development
Authors: Gajardo E. , Pagá M. , Sully J.P. 
Published: October 2008

Abstract
Several site specific studies were performed for the northeastern Venezuelan offshore development in order to determine the environmental parameters for the engineering design. The geotechnical parameters were obtained from the analysis of the soil borings, in situ tests and the high resolution seismic surveys. An evaluation of the seismic hazard was done, based on a detailed neotectonic study, the compilation of historical and instrumental seismological information, and an attenuation relationship developed for the studied area. Seismic response analyses were performed using the seismic parameters and dynamic characteristics obtained from the soil borings and in situ tests of shear waves, The met-ocean design loads of the local conditions were obtained from mathematical modeling bawd on in situ and regional measurements.
This study defines the platforms design conditions based on a probabilistic reliability approach and it has been used, among others, as a basis for the earthquake design guidelines proposed by the International Standards Organization. A sensitivity analysis was performed starting from the uncertainties of all the input parameters, in order to obtain the best estimate average design spectrum and associated coefficient of variability. The specific approach was to maintain the same safety index adopted by API RP2Adc, with a 'bias' modification factor that relates the site nominal spectra with the spectral acceleration that would lx used in order to satisfy the API requirements.
The results of this approach make possible the use of site specific detailed environmental data and the proven standard process established on the API RP2 codes, with significant cost reduction in terms of both platform and foundation design. The considerable amount of tectonic, seismological, and geotechnical information was the principal factor allowing the above methodology.

Introduction
This paper summarizes the environmental design loads to be applied in areas with WCII known site specific or local parameters and its associated uncertainties. Its make use of standard and recognized design criteria with the advantage of keeping the safety index and substantial cost reduction.

Seismic Hazard
Geology and regional tectonics. The north-west region of Venezuela shows a very complex tectonic setting controlled by the interaction of the Caribbean and South American Plates. The main active faults are El Pilar and Caribe with EW orientation and many other secondary faults with NWSE trend (Fig. 1 and 3).
Seismic Hazard Evaluation., The seismic hazard is defined as the level or value of the parameter representing ground movement (maximum acceleration, for example) that has a specific probability of being exceeded during particular defined period of time. Usually, what is obtained is the annual probability from which any other time span can be obtained.
The parameters were obtained from the existing data bases and a seismic attenuation relationship was developed for the region
Typhoon Emergency Response Planning for the South China Sea
Authors: Corona E.N. , Lynch R.D. , Riffe D. , Cardone V.J. , Cox A. , Chen H. 
Published: October 2008

Abstract
This paper describes the development, implementation and performance of a comprehensive typhoon emergency response plan (ERP) utilized during 1995 by Arco China Inc (ACI) for their offshore Hainan Is. South China Sea development. An important component of the enhanced plan is a new system to forecast winds and sea stales generated by tropical cyclones (TC) built around known uncertainties in forecasts of cyclones and well proven numerical models of the TC surface wind field and (he spectral wave field. The forecast system provides specification of time histories of the winds and waves at the site for the nominally predicted track as well as the probabilities of exceedance of critical evacuation Thresholds of wind speed and sea slate. The ERP and forecast system were operated throughout the 1995 typhoon season and evaluated at the Yacheng development, which was seriously threatened by 15 tropical cyclones between June and November. The response to these threats in terms of interruption of operations, partial or total evacuation of offshore personnel and average downtime is describe and compared to previous experiencewhich used more conventional forecast services evaluation has shown [he new system to provide significant benefit in terms of safety, efficiency and cost savings. The wind and sea slate forecast histories provided year-round by the forecast system are also of significant benefit to the management of floating production systems.

Introduction
The intensity and track of tropical cyclones are notoriously difficult to predict accurately. Faced with such uncertainties offshore operators in areas affected by cyclones (e.g. South China Sea, Gulf of Mexico, NW Australia) typically base response decisions on the predict entry of a tropical cyclone into a large watch circle, without regard to knowledge of quantifiable factors such as the uncertainty and confidence in the predicted track of a particular system, and the surface wind speed and wave height history to be expected at the offshore work site for the specific event, Such a strategy could lead tounnecessary false alarms resulting in risks to life and equipment caused by the evacuation and shutdown process, and costly downtime. Conversely, simple distance-to-site weighted decisions fail to account for the sometimes significant winds and seas generated by large but distant storms or storms with anomalous circulations, such as typhoon-northeast monsoon hybrid events in the South China Sea. This paper describes the development, implementation and performance of an enhanced emergency response plan (ERP) of Arco China Inc. (ACI), whose operations were greatly expanded in 1995 in terms of construction and drilling activities and the number of offshore personnel. The update of the ERP was considered necessary because past experience raised serious concerns that previous practices might entail considerable risk when they lead to unnecessary evacuations of large numbers of offshore personnel.
Experience in Float Over Integrated Deck - Design and Installation
Authors: Sigrist J.H. , Naudin J.C. 
Published: October 2008

ADSTRACT
Since early 1980, Technip-Geoproduction (TPG), as designer or as installation contractor, has been using with success the float over system "UNIDECK-TPG" for the transportation and installation of integrated decks for offshore platforms. The concept offers the advantages of significant savings in transportation and installation cost by minimizing the installation time and offshore hook-up and eliminating the need for a heavy Lift derrick barge.
The paper describes the technology used for the installation, the required engineering studies, the consequences of using such a concept on platform design and the selection of an appropriate barge size to be used.

INTRODUCTION
TPG has developed the integrated deck concept, called UNIDECK-TPG, with the objective at minimizing the overall cost by offering the advantage of having a deck which can be installed on a jacket as a single unit, filly completed and tested without using a conventional crane barge.
The concept has been successfully used several times in both favorable and more severe sea conditions with deck weight ranging from 2,500 to 9,500 metric tons.
The technology combines ballasting and jacking to improve the stability of the cargo barge during the transportations phase and by jacking to provide a safe and quick transfer of the deck weight onto the pre-installed jacket.
After having designed platforms in shallow waters as jack-up, this method was used first by TPG for (Fig. 1) :KOC Southern Gas Project (in early [980),the Ethylene Offshore Terminal in Egypt for EGPC (2,300 tons),the relocation of Zakurn Accommodation Platform (7,000 tons) for ADMA OPCOthe ADNOC Khuff Gas Production Platform (2,500 tons),
and recently for :" the North Field Qatargas Process and Utilities Platform (7,500 tons),the COB-PI Production Platform, for Sonangol and for Elf Exploration Angola (9,500 tons) for which TPG acted as general contractor. The deck has been installed early 1996 with 1.2 m significant wave height. This is the first time that such installation method has been used in the long swell of south Atlantic Ocean.
The UNIDECK-TPG method is applicable to three main categories :in shallow water where there is not sufficient draft for a derrick barge to enter the site," when heavy lift derrick barges are not readily available resulting in a prohibitive mobilization cost,when an integrated deck would be too heavy for existing derrick barge.
In each case, the installation method can be adapted to the environmental conditions and to the weight and final elevation of the deck so as to minimize the cost of the operation.
Installation of the Troll Phase I Gravity Base Platform
Authors: Andenæs E. , Skomedal E. , Lindseth S. 
Published: October 2008

Abstract
The TROLL Phase 1concrete Gravity Base Platform is located in 303 m of water in the Norwegian Trench some 80 kilometers northwest of Bergen. The platforms wi11be a major gas supplier to the European market far into the next century. This paper describes the major aspects in the design, preparation and performance of the platform installation operation.
The extreme height of the structure was a challenge for design and performance of the marine operations, particular when passing a "shallow area" with minimum depth of237 m. The foundation soils at the Troll Field required skirt piles to record breaking 36 m depth in order to sustain the extreme North Sea weather conditions.
The potential of intolerable horizontal soil pressure on the skirt walls from large soil displacements during penetration was the dominating aspect of the skirt penetration. Extensive engineering supplemented with model testing and planning were conducted in the development of systems and procedures for monitoring and manipulation of acting loads on the skirt walls.
The success of the design, planning and performance of the operation is documented through comparison between observed and predicted performance of main operation parameters.

Introduction
Field Information, The TROLL Phase 1Gas Platform was installed in May 1995. The Troll Field is located in the Norwegian sector of the North Sea. The platform will be a major supplier of gas to the European market far into the next century. Design operating life is 70 years and the maximum production rate some 84 × 106 Sm3/day (3 BCF/day).
Norske Shell was appointed as field development operator in 1988. The contract for engineering, procurement and construction of the concrete Gravity Base Structure (GBS) including tow out and installation of the platform at the Troll Field was given ?)Seconded to Norske Shell during project.
Tables and figures at the end of the paper, to the Aker company Norwegian Contractors in March 1991,. Watoil will take over as production operator in June 1996.
Platform Design and Site Conditions. The Troll Field is in the Norwegian Trench. At the platform location the water depth is 303 m, The upper 74 m of soil consists of more or less normally consolidated, homogeneous clay. From seabed to 16.5 m depth the clay is sofi to firm with high plasticity. This layer is called Soil Unit I. In Soil Unit 11, below 16,5 m, the plasticity becomes medium. The strength increases gradually by depth, A summary of soil data is given in Figure 1.
The 472 m high structure including topsides is the tallest structure that has ever been moved on the earth's surface. An artists view of the platform is shown in Figure 2. The substructure is made of concrete and is a Co deep SP-4 -19-R design, comprising skirt piles, 19 caisson cells, one Siegel and four shafts. Figure 3 provides a general view and a cross section.