Calculation of equivalent static loads and its application

Choi, Woo-Seok; Park, Keun-Bae; Park, Gyung-Jin

doi:10.1016/j.nucengdes.2005.05.030

Cited by 22 publications

(14 citation statements)

References 14 publications

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“…7. The first modal frequency of the wind turbine structure (ω n1 ) is used for obtaining DAF since it lies in the range of 75% to 120% of the excitation frequencies and as a result, dynamic amplifications of responses are expected [6]. Thus, the dynamic load is converted to ESL using DAF.…”

Section: Nonlinear Static Analysismentioning

confidence: 99%

“…Current forces are calculated using power law as shown in Eq. (6). (6) where, is the current speed at elevation z, z = 0 at the surface, is the surface current speed, h is the water depth, α is an exponent, typically 1/7.…”

Section: Nonlinear Static Analysismentioning

confidence: 99%

“…Typically, these tolerances are specified in some codes of practice or a design specification supplied by the client that may be dictated by the turbine manufacturer. Maximum allowable rotation at pile head after installation (as per DNV code) is specified with 0.25° limit on "Tilt" at the nacelle level [6]. The maximum rotation at the pile head is limited to 0.22° and the UC (unity check) ratio is limited to 0.8.…”

Section: Structural Designmentioning

confidence: 99%

See 2 more Smart Citations

Simplified Design Procedure of Monopile Foundation for Offshore Wind Turbine in Gujarat, India

Srikanth¹,

Alluri²,

Balakrishnan³

et al. 2017

JSOE

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OWTs (offshore wind turbines) are currently considered as a reliable source of renewable energy. OWT support structures account for 20%-25% of the capital cost for offshore wind installations. Pre-feasibility studies involving estimation of preliminary dimensions of the wind turbine structure need to be performed for initial costing to arrive at the commercial viability of the project. The main objective of the paper is to obtain preliminary configuration for commercial viability and approximate sizing of the foundation pile. Design equations and nomograms are proposed for quick preliminary design of monopile founded wind turbines located offshore of Gujarat. Parametric studies are carried-out on various configurations of a hollow monopile by varying water depths and properties of sand. A nonlinear static analysis of substructure is performed considering aerodynamic forces and hydrodynamic forces for various structural and soil parameters. The sub-structure design of wind turbine is based on API (American petroleum institute) standards. A simplified design methodology for monopile support structure under extreme loading condition is presented based on multivariable linear regression analysis. The input variables for the regression analysis are hydrodynamic data, angle of internal friction of sand, and the output variables are length and outer diameter of monopile. This simplified methodology is applicable in pre-studies of wind power parks.

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Section: Nonlinear Static Analysismentioning

confidence: 99%

Section: Nonlinear Static Analysismentioning

confidence: 99%

Section: Structural Designmentioning

confidence: 99%

See 1 more Smart Citation

Simplified Design Procedure of Monopile Foundation for Offshore Wind Turbine in Gujarat, India

Srikanth¹,

Alluri²,

Balakrishnan³

et al. 2017

JSOE

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“…Kang et al [11] proposed structural optimization approach under equivalent static load, generating identical displacements as caused by dynamic excitations. Choi et al [12] presented a method, based on modal analysis, transforming dynamic loads into equivalent static one.…”

Section: Introductionmentioning

confidence: 99%

Graph based discrete optimization in structural dynamics

Błachowski¹,

Gutkowski²

2014

Bulletin of the Polish Academy of Sciences: Technical Sciences

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Abstract. In this study, a relatively simple method of discrete structural optimization with dynamic loads is presented. It is based on a tree graph, representing discrete values of the structural weight. In practical design, the number of such values may be very large. This is because they are equal to the combination numbers, arising from numbers of structural members and prefabricated elements. The starting point of the method is the weight obtained from continuous optimization, which is assumed to be the lower bound of all possible discrete weights. Applying the graph, it is possible to find a set of weights close to the continuous solution. The smallest of these values, fulfilling constraints, is assumed to be the discrete minimum weight solution. Constraints can be imposed on stresses, displacements and accelerations. The short outline of the method is presented in Sec. 2. The idea of discrete structural optimization by means of graphs. The knowledge needed to apply the method is limited to the FEM and graph representation.The paper is illustrated with two examples. The first one deals with a transmission tower subjected to stochastic wind loading. The second one with a composite floor subjected to deterministic dynamic forces, coming from the synchronized crowd activities, like dance or aerobic.

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“…Although, the above researches are limited to seismic loads, the transformation is based on experimental codes, and it lacks generality. Choi et al (2005) and Choi and Park (1999a, b) proposed several methods to find reliable equivalent static loads from dynamic loading. Two kinds of ESLs are considered in the literature: exact and approximate.…”

Section: Introductionmentioning

confidence: 99%

Shape optimization of structures under earthquake loadings

Âkbari

Sadoughi

2013

Struct Multidisc Optim

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The optimum design of structures under static loads is well-known in the design world; however, structural optimization under dynamic loading faces many challenges in real applications. Issues such as the time-dependent behavior of constraints, changing the design space in the time domain, and the cost of sensitivities could be mentioned. Therefore, optimum design under dynamic loadings is a challenging task. In order to perform efficient structural shape optimization under earthquake loadings, the finite element-based approximation method for the transformation of earthquake loading into the equivalent static loads (ESLs) is proposed. The loads calculated using this method are more accurate and reliable than those obtained using the building regulations. The shape optimization of the structures is then carried out using the obtained ESLs. The proposed methodologies are transformed into user-friendly computer code, and their capabilities are demonstrated using numerical examples.

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Calculation of equivalent static loads and its application

Cited by 22 publications

References 14 publications

Simplified Design Procedure of Monopile Foundation for Offshore Wind Turbine in Gujarat, India

Simplified Design Procedure of Monopile Foundation for Offshore Wind Turbine in Gujarat, India

Graph based discrete optimization in structural dynamics

Shape optimization of structures under earthquake loadings

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