scholarly journals Experimental analysis and mechanical modeling of T-stubs with four bolts per row

2021 ◽  
Author(s):  
Massimo Latour ◽  
Gianvittorio Rizzano
Keyword(s):  
Steel Structures ◽  
Experimental Tests ◽  
Analytical Models ◽  
Fe Model ◽  
Yield Line ◽  
Collapse Mechanisms ◽  
Steel Members ◽  
Eurocode 3 ◽  
Set Up ◽  
Definition Of

The behavior of steel structures is significantly affected by the connections between the steel members. For this reason, special attention to the prediction of the joint rotational behavior is devoted by Eurocode 3 which provides the well-known component method. In EC3, starting from the results of several researches, the formulations for the characterization of the behavior of T-stubs with two bolts per row are given, but with reference to T-stubs with four bolts per row, even though they are present in many actual structural situations, the limited number of experimental tests and analytical models has not led yet to the codification of this component in the code. In this work, starting from the results of three experimental tests on T-stub with four bolts per row, carried out at the laboratory on materials and structures of the University of Coimbra, a FE model in ABAQUS has been set up in order to analyze the yield line patterns corresponding to the different collapse mechanisms. Subsequently, with reference to the yield line shape different from that of T-stub with two bolts per row, the effective lengths have been revaluated applying an energy approach. The definition of the effective width for all the possible collapse mechanisms allowed to set up a proposal for determining the resistance of T-stubs with 4 bolts per row consistent with the approach provided by Eurocode 3. The model accuracy has been verified by means of a comparison with the results provided by a numerical analysis.

SEA model for structural acoustic coupling by means of periodic finite element models of the structural subsystems

2021 ◽  
Vol 263 (1) ◽  
pp. 5301-5309
Author(s):  
Luca Alimonti ◽  
Abderrazak Mejdi ◽  
Andrea Parrinello
Keyword(s):  
Finite Element ◽  
Numerical Approach ◽  
Unit Cell ◽  
Analytical Models ◽  
Finite Element Models ◽  
Fe Model ◽  
Acoustic Coupling ◽  
Representative Unit Cell ◽  
Definition Of ◽  
Acoustic Treatment

Statistical Energy Analysis (SEA) often relies on simplified analytical models to compute the parameters required to build the power balance equations of a coupled vibro-acoustic system. However, the vibro-acoustic of modern structural components, such as thick sandwich composites, ribbed panels, isogrids and metamaterials, is often too complex to be amenable to analytical developments without introducing further approximations. To overcome this limitation, a more general numerical approach is considered. It was shown in previous publications that, under the assumption that the structure is made of repetitions of a representative unit cell, a detailed Finite Element (FE) model of the unit cell can be used within a general and accurate numerical SEA framework. In this work, such framework is extended to account for structural-acoustic coupling. Resonant as well as non-resonant acoustic and structural paths are formulated. The effect of any acoustic treatment applied to coupling areas is considered by means of a Generalized Transfer Matrix (TM) approach. Moreover, the formulation employs a definition of pressure loads based on the wavenumber-frequency spectrum, hence allowing for general sources to be fully represented without simplifications. Validations cases are presented to show the effectiveness and generality of the approach.

Calculation of Fatigue Capacity for a Subsea Wellhead Connector

2020 ◽  
Author(s):  
Seyed H. Hashemizadeh ◽  
Venu Sunkavilli ◽  
Torfinn Hørte ◽  
Per Osen
Keyword(s):  
Fatigue Life ◽  
Hot Spot ◽  
High Strength Steels ◽  
Steel Structures ◽  
High Strength ◽  
Element Model ◽  
Fe Model ◽  
Specific Advice ◽  
Drilling Operations ◽  
Set Up

Abstract In the 2019 version of DNVGL-RP-C203 Fatigue Design of Offshore Steel Structures, significantly improved methods have been added on how to establish M-N curves representing the fatigue resistance of preloaded connectors subject to cyclic bending. The M-N curve parameters are typically provided by the manufacturer and used by operators and drilling contractors for calculating the wellhead fatigue life for planned drilling operations. DNVGL-RP-C203 provides specific advice on how to establish design M-N curves based on analysis, and the augmentation by possible testing, where testing may grant more favorable M-N curves and thus extended fatigue life for any given case. The paper provides background and introduction to the improved analysis methodology and relevant S-N curves for high-strength steels for wellhead systems, given in the 2019 version of the DNVGL-RP-C203. It includes a worked example in order to demonstrate the detailed use of the method, applied on a Baker Hughes preloaded BOP connector, connected to a 27” wellhead mandrel. This example describes the finite element model set up, FE model mesh refinement in hot-spots, the application of cyclic loads, extraction of hot-spot cyclic stresses, and the establishment of the M-N curve for the connector.

Simulation of the Residual Stress of Cold-Formed Thin-Wall Steel Members and Calculation of Load under Its Influence

2005 ◽  
Vol 490-491 ◽  
pp. 112-117
Author(s):  
Feng Zhao ◽  
Hua Chen Liu
Keyword(s):  
Residual Stress ◽  
Initial Stress ◽  
Technical Specification ◽  
Steel Structures ◽  
Thin Wall ◽  
Integral Points ◽  
Elastic Plastic ◽  
Steel Members ◽  
Specific Object ◽  
Set Up

Because of the particularity of distribution of the residual stress of cold-formed thin-wall steel members, now there has not yet been a proper method for directly considering the influence of the residual stress in calculating the reliable capacity of carrying load of cold-formed thin-wall steel members, and such is the typical case in China’s National Technical Specification of Cold-formed Thin-wall Steel Structures GB50018-2002. With the cold-formed thin-wall channel steel taken as specific object in this study as well as assumed to be ideal elastic-plastic body, their finite modular models are set up in ANSYS. According to the tested results and the distributing rules of residual stress, the models of the residual stress of cold-formed thin-wall channel steel are established close to the factual data, and also the initial stress file is set up that can describe the magnitude and distribution of the residual stress. The file has two features: first, it is likely to find out about the rules of the cold-steel residual stress varying in the direction of thickness by using the values of residual stress at some integral points in thickness direction of a specified module , and second, it is applicabled to simulate various distributions of residual stress. So the ultimate load of the member can be worked out and elastic-plastic calculating problem of cold-formed thin-walled steel sections can be easily solved by introducing the initial stress file into the stability analysis of ANSYS.

scholarly journals EXPERIMENTAL STUDIES OF UNPROTECTED AND PROTECTED STEEL STRUCTURES UNDER FIRE

2016 ◽  
Author(s):  
Véronique Saulnier ◽  
Sébastien Durif ◽  
Abdelhamid Bouchaïr ◽  
Philippe Audebert ◽  
Mohamed Lahmar
Keyword(s):  
Fire Protection ◽  
Steel Plate ◽  
Experimental Studies ◽  
Steel Structures ◽  
Experimental Tests ◽  
Steel Plates ◽  
Experimental Protocol ◽  
Plate Temperature ◽  
Angle Section ◽  
Set Up

<p>Preliminary fire experimental tests have been carried out on steel plates protected with intumescent coating.</p><p>The tests evaluated and measured the heating of steel plates with various geometrical configurations: shape, size. A first test on an equal leg angle section showed interesting results with different coating expansion on the faces of the section.</p>The second test campaign is done with different protections to compare behaviors of four steel plates. The first objective is to set up an experimental protocol for future tests. Those results are used to evaluate analytical prevision of steel plate temperature with and without fire protection.

scholarly journals Creep-free fire analysis of steel structures with Eurocode 3 material model

2016 ◽  
Vol 7 (3) ◽  
pp. 234-248 ◽  
Author(s):  
Neno Toric ◽  
Rui Rui Sun ◽  
Ian W. Burgess
Keyword(s):  
Steel Structures ◽  
Material Model ◽  
Steel Beams ◽  
Heating Rates ◽  
Content Type ◽  
Simply Supported ◽  
Fire Engineering ◽  
Steel Members ◽  
Steel Material ◽  
Eurocode 3

Purpose This paper aims to propose a methodology to remove inherent implicit creep from the Eurocode 3 material model for steel and to present a creep-free analysis on simply supported steel members. Design/methodology/approach Most of the available material models of steel are based on transient coupon tests, which inherently include creep strain associated with particular heating rates and load ratios. Findings The creep-free analysis aims to reveal the influence of implicit creep by investigating the behaviour of simply supported steel beams and columns exposed to various heating regimes. The paper further evaluates the implicit consideration of creep in the Eurocode 3 steel material model. Originality/value A modified Eurocode 3 carbon steel material model for creep-free analysis is proposed for general structural fire engineering analysis.

Equivalent Layer Approaches to Predict the Bisymmetric Hydrostatic Collapse Strength of Flexible Pipes

2018 ◽  
Author(s):  
José Renato M. de Sousa ◽  
Marcelo K. Protasio ◽  
Luis V. S. Sagrilo
Keyword(s):  
Three Dimensional ◽  
Experimental Tests ◽  
Fe Model ◽  
Flexible Pipe ◽  
Collapse Mechanisms ◽  
Collapse Strength ◽  
Flexible Pipes ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Radial Loading

The hydrostatic collapse strength of a flexible pipe is largely dependent on the ability of its carcass and pressure armor to resist radial loading and, therefore, its prediction involves an adequate modeling of these layers. Hence, initially, this work proposes a set of equations to estimate equivalent thicknesses and physical properties for these layers, which allows their modeling as equivalent orthotropic cylinders. These equations are obtained by simulating several two-point static ring tests with a three-dimensional finite element (FE) model based on beam elements and using these results to form datasets that are analyzed with a symbolic regression (SR) tool. The results of these analyses are the closed-form equations that best fit the provided datasets. After that, these equations are used in conjunction with a three-dimensional shell FE model and a previously presented analytical model to study the dry and wet hydrostatic collapse mechanisms of a flexible pipe. The predictions of these models agreed quite well with the collapse pressures obtained in experimental tests thus indicating that the use of the equivalent approach is promising.

Improvements on the Numerical Analysis of the Coupled Extensional–Torsional Response of a Flexible Pipe

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Héctor E. M. Muñoz ◽  
José R. M. de Sousa ◽  
Carlos Magluta ◽  
Ney Roitman
Keyword(s):  
Cross Sections ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Axial Rotation ◽  
Nonlinear Finite Element ◽  
Analytical Models ◽  
Fe Model ◽  
Flexible Pipe ◽  
Torsional Response ◽  
Axial Twist

In this paper, the coupled extensional–torsional behavior of a 4 in. flexible pipe is studied. The pipe is subjected to pure tension and two different boundary conditions are considered: ends free and prevented from axially rotating. The response of the pipe is predicted with a three-dimensional nonlinear finite element (FE) model. Some aspects of the obtained results are discussed, such as the effect of restraining the axial rotation at the extreme sections of the model; the effect of friction or adhesion between the layers of the pipe on the induced axial rotation (or torque) and elongation; and the reduction to simple plane behavior usually assumed by analytical models. The numerical results are compared to the ones measured in experimental tests. Reasonable agreement is observed between all results pointing out that the analyzed pipe is torque balanced and that friction mainly affects the axial twist induced by the applied tension. Moreover, the cross sections of the pipe remain straight with the imposed load, but different axial rotations are found in each layer.

Dynamic Modeling and Experimental Validation of Eddy Current Dampers and Couplers

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Andrea Tonoli ◽  
Nicola Amati
Keyword(s):  
Eddy Current ◽  
Mechanical Impedance ◽  
Experimental Tests ◽  
Analytical Models ◽  
Basic Principles ◽  
Practical Applications ◽  
Eddy Current Damper ◽  
Band Limited ◽  
Definition Of ◽  
Damping Torque

The interest in eddy current dampers is increasing especially in aeronautic and automotive industry. Such devices seem to be a valid alternative to conventional fluid film and viscoelastc dampers. Even if several papers have been published on this topic, an electromechanical model taking into account both the resistance and the inductance of the conductor is still lacking. The aim of the present paper is to model the electromagnetic interaction of an eddy current device operating as a damper or as a coupler and to validate it by means of experimental tests performed at steady state and vibrating about a fixed position. The study is based on the computation of the damping torque starting from the basic principles. The analytical models are developed using the bond graph formalism that allows to obtain purely mechanical analogs of the electromechanical system. The main results are the identification of eddy current damper dynamic model and the definition of a set of “conversion rules” allowing to readily obtain the mechanical impedance from the torque to slip speed characteristic and vice versa. The experimental results confirm the band limited effect of the damping, which cannot be neglected for practical applications. The effect can be exploited in eddy current couplers to filter higher order disturbances.

On the Coupled Extensional–Torsional Response of Flexible Pipes

2009 ◽  
Author(s):  
He´ctor E. M. Merino ◽  
Jose´ R. M. de Sousa ◽  
Carlos Magluta ◽  
Ney Roitman
Keyword(s):  
Cross Sections ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Axial Rotation ◽  
Analytical Models ◽  
Fe Model ◽  
Flexible Pipe ◽  
Torsional Response ◽  
Flexible Pipes ◽  
Axial Twist

In this paper, the coupled extensional-torsional behavior of a 4″ flexible pipe is studied. The pipe was subjected to pure tension and two different boundary conditions were considered: ends free and prevented from axially rotating. The response of the pipe is predicted with a three-dimensional nonlinear finite element (FE) model. Some aspects of the obtained results are discussed, such as: the effect of restraining the axial rotation at the extreme sections of the model; the effect of friction or adhesion between the layers of the pipe on the induced axial rotation (or torque) and elongation; and the reduction to simple plane behavior usually assumed by analytical models. The numerical results are compared to the ones measured in experimental tests performed at COPPE/UFRJ. Reasonable agreement is observed between all results pointing out that the analyzed pipe is torque balanced and that friction mainly affects the axial twist or torque led by the applied tension. Moreover, the cross-sections of the pipe remain straight with the imposed load, but different axial rotations are found in each layer.

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