Development of a technology type factor for jacket structures for offshore wind turbines in Rhode Island

Abstract

A marine spatial planning approach was used to locate possible sites for offshore wind development in Rhode Island. In connection with the Rhode Island ocean special area management plan, a technology development index was developed by Spaulding et al. (2010) to quantify the technical challenges of a particular site relative to its potential power production. A component of this index is the technology type (TT) factor, which quantifies the relative cost of a structure/ foundation system as a function of environmental loading, water depth, and soil conditions. This paper presents the development of TT factors for jacket type support structures that is proposed for supporting the offshore wind turbines in Rhode Island Sound. TT factors were calculated by the total weight of the jacket and piles for a given water depth and soil conditions normalized by the weight of a reference structure. Jacket structure weights were determined by a frequency driven finite element analysis using the program ANSYS. The structure was subjected to hydrodynamic and quasi-static turbine loads from 50-year extreme wind and the 100-year extreme wave loading in Rhode Island Sound to determine the ultimate stresses in the structural members. Pile foundation weights were determined from an analysis of the axial capacity and the lateral capacity using commercially available pile design software. Jacket and foundation weights were calculated for water depth ranging from 30 m to 60 m and for three representative soil types. These analyses resulted in a Technology Type factor that varies with water depth according to a 2nd order polynomial, and also with soil type. The results were compared to the weights of two existing jacket structures in Europe and found to be in agreement with the upper bound estimate derived from this study. The Technology Type factor derived in this study was also in good agreement with the published actual cost (normalized) of jacket type foundations used in the United Kingdom. V C 2012 American Institute of Physics.

Soil-structure interaction on the response of jacket-type offshore wind turbine

“…2(c)). Brown et al 7,26 introduced the notion of pmultipliers to obtain p-y curves for piles in a group with the aim of assessing the pile group behavior from that of the single pile. The dynamic soil reaction at a certain depth for piles in a group, P g , is given as: (13) where P m is the p-multiplier, and P is the soil reaction at the same depth for a single pile.…”

“…Although offshore wind energy has experienced rapid development, there is still a growing global demand for wind energy production. [6][7][8][9] Various offshore wind farms have been operated since the 1990s. Up to now, most wind turbines have been installed with monopile or gravity foundations in shallow water depths of 20-30 m. With the aid of technologies from the oil and gas industry, research work is ongoing for greater water depths of 40-100 m, where hydrodynamic transparent designs, such as jacket structures are commonly used.…”

Dynamic effects in the response of offshore wind turbines supported by jackets under wave loading

“…The dimension and mass of the deck are not changed between the three models. The structural and material damping of all three models is modeled with Rayleigh damping, with x = 2% [24,25] for periods of the 1 st and 5 th lateral vibration mode of the model [26]. It should be noted that there is no consensus in the literature for the structural periods used in calibrating Rayleigh damping parameters.…”

Reliability-Based Serviceability Limit State Design of a Jacket Substructure for an Offshore Wind Turbine

“…There was a 4496 MW increase between 2017 and 2018, and this was the most significant yearly addition to the capacity up until 2018. Further to the rapid development of offshore wind energy until now, the global demand is still growing for wind energy production [2,3]. The total installed capacity of offshore wind power is expected to be increased to 120 GW by 2030.…”