Fatigue assessment based on hot-spot stresses obtained from the global dynamic analysis and local static sub-model

2019 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Cristiane Oliveira Viana ◽  
Hermes Carvalho ◽  
José Correia ◽  
Pedro Aires Montenegro ◽  
Raphael Pedrosa Heleno ◽  
...  
Keyword(s):  
Dynamic Analysis ◽  
Modal Analysis ◽  
Static Analysis ◽  
Structural Model ◽  
Hot Spot ◽  
Superposition Method ◽  
Hot Spot Stress ◽  
Content Type ◽  
Global Dynamic ◽  
Critical Detail

Purpose The purpose of this paper is to evaluate the fatigue process through the dynamic analysis of the global structural model and local static sub-modelling in a critical detail using the hot-spot stress approach. The detail was studied in three different positions at the “Alcácer do Sal” access viaduct, and the methodologies from the IIW and Eurocode EN 1993-1-9 were compared. Design/methodology/approach In this study, the fatigue life process based on the hot-spot stress approach was evaluated using a global dynamic analysis and a local sub-modelling based on a static analysis of welded connections in the “Alcácer do Sal” railway structure, Portugal, taking into consideration the recommendations from IIW and Eurocode EN 1993-1-9. The hot-spot stresses were calculated through the static analysis of the sub-model of the welded connection for each vibration mode with the aim to obtain the temporal stresses using the modal coordinates and modal stresses of the extrapolation points. The Ansys® and Matlab® softwares were used for the numerical analysis and the hot-spot stress calculations, respectively. Findings The proposed methodology/approach to obtain fatigue assessment is based on the modal analysis of the global structural model and local static sub-modelling. The modal analysis was used to extract the boundary conditions to be used in the local model to determine the temporal stresses of the extrapolation points. Based on the modal superposition method, the stresses as function of time were obtained for fatigue life evaluation of a critical detail by the hot-spot stress approach. The detail was studied in three different positions. Originality/value In the present study, a global-local fatigue methodology based on dynamic analysis of the global structural model and local static sub-modelling of the critical detail using the hot-spot stress approach is proposed. Herein, the modal analysis of the global structural model supported by the modal superposition method was used to obtain the matrix of modal coordinates. The static analysis of the local sub-model for each mode from the modal analysis of global structural model was done to estimate the hot-spot stresses. The fatigue damage calculation was based on S-N curve of the critical detail and rainflow method. The IIW recommendation proved to be more conservative compared to the proposed rules in the Eurocode EN 1993-1-9. The global-local modelling based on dynamic analysis is an important and effective tool for fatigue evaluation in welded joints.

Dynamic analysis of swivel construction method under multi-variable coupling effects

2019 ◽  
Vol 10 (4) ◽  
pp. 580-598
Author(s):  
Wang Jiawei ◽  
Sun Quansheng
Keyword(s):  
Dynamic Analysis ◽  
Dynamic Model ◽  
Static Analysis ◽  
Friction Stress ◽  
Construction Method ◽  
Coupling Effects ◽  
Content Type ◽  
Multiple Factors ◽  
Real State ◽  
Variable Coupling

Purpose Swivel construction is a new bridge construction method, which can minimize the impact on railway and highway traffic. Previous studies were based on single factor and static analysis, which cannot reflect the real state of structures. The purpose of this paper is to establish a dynamic model of the structure and to analyze the situation under multi-variable coupling effects to accurately simulate the real state of the structure. Design/methodology/approach Finite element software ANSYS was used to establish dynamic model of turntable structure and then to analyze the effects of multiple factors on total stress, friction stress and slipping distance of the turntable structure. Findings It is concluded that the unbalanced weight and radius of spherical hinges have great influence on the turntable structure, so the design should be strictly considered. Friction stress and angular acceleration have little effect on the turntable structure. Originality/value This paper provides simulation of the whole process of swivel construction method. Whereas previous studies focused on static analysis, this paper focuses on the dynamic analysis of swivel construction method. The mechanics of the swivel structure under multiple factors was analyzed. According to the analysis results, the design parameters of the turntable structure are optimized.

scholarly journals The static substructure method for dynamic analysis of structures

1987 ◽  
Vol 20 (4) ◽  
pp. 264-268
Author(s):  
Menglin Lou
Keyword(s):  
Dynamic Response ◽  
Dynamic Analysis ◽  
Static Analysis ◽  
Superposition Method ◽  
Ritz Vector ◽  
Substructure Method ◽  
Large Structures

In this paper, the static substructure method based on the Ritz vector direct superposition method is suggested for analysing the dynamic response of structures. The advantage of this algorithm is that the computer cost can be reduced and the static analysis and the dynamic analysis of large structures can be simplified by using the identical static substructure method.

scholarly journals Finite Element Analysis of F1 Halo Safety Structure

2021 ◽  
Vol 9 (12) ◽  
pp. 1686-1689
Author(s):  
Manas Metar
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Dynamic Analysis ◽  
Modal Analysis ◽  
Static Analysis ◽  
Element Analysis ◽  
Permissible Levels

Abstract: The Federation Internationale de L’Autobile (FIA) has been working on improving safety of drivers in open wheel racing series. Numerous incidents caused serious impacts on drivers’ lives. The car-to-car collision, car to environment collision and injuries due to flying debris are common threats to these drivers. In 2016 the introduction of Halo surrounding the cockpit was appreciated by the FIA. The following study includes the analysis of this Halo system using Finite Element Analysis (FEA). The dynamic, static and modal analysis is carried out with the help of Simscale software and the results obtained showed the values under permissible levels. Keywords: Finite Element Analysis, Static Analysis, Modal Analysis, Dynamic Analysis, F1 Halo, FIA.

Development of an equivalent static method for the approximation of the dynamic response of offshore structures

2019 ◽  
Vol 36 (4) ◽  
pp. 1121-1141 ◽  
Author(s):  
Apostolos Koukouselis ◽  
Konstantinos Chatziioannou ◽  
Euripidis Mistakidis ◽  
Vanessa Katsardi
Keyword(s):  
Dynamic Response ◽  
Dynamic Analysis ◽  
Earthquake Engineering ◽  
Structural Model ◽  
Computational Cost ◽  
Time History ◽  
Offshore Structures ◽  
Design Approach ◽  
Wave Loading ◽  
Content Type

Purpose The design of compliant towers in deep waters is greatly affected by their dynamic response to wave loads as well as by the geometrical and material nonlinearities that appear. In general, a nonlinear time history dynamic analysis is the most appropriate one to be applied to capture the exact response of the structure under wave loading. However, this type of analysis is complex and time-consuming. This paper aims to develop a simplified methodology, which can adequately approximate the maximum response yielded by a dynamic analysis by means of a static analysis. Design/methodology/approach Various types of time history dynamic analysis are first applied on a detailed structural model, ranging from linear to fully nonlinear, that are used as reference solutions. In the sequel, a simplified analysis model is formulated, capable of reproducing the response of the entire structure with significantly reduced computational cost. In the next stage, this model is used to obtain the linear and nonlinear response spectra of the structure. Finally, these spectra are used to formulate a simplified design approach, based on equivalent static loads. Findings This simplified design approach produces good results in cases that the response is mainly governed by the first eigenmode, which is the case when compliant towers are considered. Originality/value The present paper borrows ideas from the area of earthquake engineering, where simplified methodologies can be used for the design of a certain class of structures. However, the development of a simplified methodology for the approximation of the dynamic behavior of offshore structures under wave loading is a much more complex problem, which, to the authors’ knowledge, has not been addressed till now.

scholarly journals STRUCTURAL ANALYSIS OF JACKET FOUNDATIONS FOR OFFSHORE WIND TURBINES IN TRANSITIONAL WATER

Brodogradnja ◽  
2021 ◽  
Vol 72 (1) ◽  
pp. 109-124
Author(s):  
Issa Fowai ◽  
◽  
Zhang Jianhua ◽  
Ke Sun ◽  
Bin Wang ◽  
...  
Keyword(s):  
Dynamic Analysis ◽  
Modal Analysis ◽  
Static Analysis ◽  
Wind Turbines ◽  
Offshore Wind ◽  
Von Mises Stress ◽  
Mode Shapes ◽  
Offshore Wind Turbines ◽  
Static And Dynamic Analysis ◽  
Von Mises

Most of the offshore wind turbines (OWT) recently installed in Europe, China and North America are in shallow water. However, unlocking the full potential of OWT lies in deeper waters. Jacket substructures have presented themselves as a reliable foundation concept for transitional water depth. This study focuses on the structural static and dynamic analysis of the traditional jacket substructures (with X and K bracing) and the recently patented three-legged twisted jackets (with a twisted angle of 30 and 60 degrees) for deployment in transitional water (beyond 60 m). To facilitate comparison, the dimensions of all the jackets remain the same, while, the geometric configurations are distinct. Static analysis was implemented to better understand the global load bearing behaviour of the jackets. First, the global displacement patterns at the tower top are compared. The individual reactions at mud-line were investigated, followed by the evaluation of the maximum von Mises stress. Subsequently, this research went on to investigate the effect of dynamic loading. In this dynamic analysis, three main critical points were considered, including the wave point (67 m), the platform and the tower top. A modal analysis was performed to compute the mode shapes and natural frequencies for all the jackets. The first five modes of all the jackets were also checked against the results available for the OC4 project. A similar analytical approach was adopted for the structural design of monopile or tripod foundations for offshore wind turbines. The results showed that in the static analysis both the traditional jackets and the twisted jackets were safe under the provided load combination. The twisted jacket proved to possess excellent structural behaviour compared to the traditional four-legged jackets, while maintaining the merits of lower material usage with fewer nodes. Analysing the von Mises stress revealed that the maximum stress occurred at the transition piece and close to the working platform. The modal analysis results of the jackets demonstrated that the twisted jackets (30 and 60 degrees) with the first natural frequency of 0.29 and 0.31 Hz fell under the soft-stiff design category whereas the traditional four-legged jackets were classified as stiff-stiff designs. The discovered structural performance of OWTs equipped with various jacket foundations contributes to the preliminary structural selection and optimal design of foundations of OWTs to be installed in transitional water.

scholarly journals Analysis about Planning and Modification of the Upper and Lower Structures of the 38 Floor Apartment SkyHouse Project with Equivalent Static Analysis

Neutron ◽  
2022 ◽  
Vol 21 (2) ◽  
pp. 80-96
Author(s):  
Agus Fernando ◽  
Syahwandi ◽  
Resi Aseanto ◽  
Agung Sumarno
Keyword(s):  
Dynamic Analysis ◽  
Static Analysis ◽  
Structural Model ◽  
Structural Models ◽  
Actual Situation ◽  
Base Shear ◽  
Accurate Analysis ◽  
Analysis Process ◽  
Earthquake Force ◽  
The Difference

Abstract The modeled building structure is a regular building, with the number of levels being varied. The structural model is divided into 38-level portals. This research uses the help of the SAP2000 v21 program to facilitate the earthquake analysis process. The results of the study that will be compared are displacements between levels and base shear that occur due to earthquake forces. The results of the analysis have shown that static analysis produces greater results for the structural models compared to dynamic analysis. The difference in displacement between levels produced by the two methods in the three structural models is still included in the displacement limits between levels of permission required in SNI 1726-2012, so that the three models can still be analyzed by static analysis and dynamic analysis. Because the results of displacement and base shear in static analysis are greater than dynamic analysis, static analysis is safer if used for earthquake force loading in general structural calculations. Although in earthquake analysis, dynamic analysis is a more accurate analysis because the analysis process is closer to the actual situation.

Fatigue assessment of a high-speed railway composite steel-concrete bridge by the hot-spot stress method

2018 ◽  
Vol 9 (3) ◽  
pp. 337-354 ◽  
Author(s):  
Guilherme Alencar ◽  
Gonçalo Ferreira ◽  
Abílio M.P. de Jesus ◽  
Rui Calçada
Keyword(s):  
Fatigue Damage ◽  
High Speed ◽  
Hot Spot ◽  
Superposition Method ◽  
High Speed Railway ◽  
Fatigue Assessment ◽  
Content Type ◽  
Railway Traffic ◽  
Composite Steel ◽  
Hotspot Stress

PurposeThe purpose of this paper is to investigate the fatigue performance of a welded detail from a composite steel-concrete railway twin girder bridge caused by a passenger train circulating at varying speeds, by identifying the dynamic amplification scenarios induced by resonance. For this purpose, the hotspot stress method is used, instead of the traditional nominal stress methods.Design/methodology/approachThis paper assesses the fatigue behavior of a welded connection considering critical stress concentration locations (hotspot). Finite element analysis (FEA) is applied, utilizing both a global and a local submodel, made compatible by displacements field interpolation. The dynamic response is obtained through the modal superposition method. Stress cycles are extracted with the rainflow counting method and the fatigue damage is calculated with Palmgren-Miner’s rule. The feasibility of five submodels with different mesh densities, i.e. 1, 2, 4, 8 and 20 mm is verified.FindingsAn increase in the fatigue damage due to the resonance effect was found for the train traveling at a speed of 225 km/h. A good agreement between the computed fatigue damage for the submodels is achieved. However, a non-monotonic hotspot stress/fatigue damage vs mesh density convergence was observed with a peak observed for the 4 mm model, which endorses the mesh sensitivity that could occur when using the surface stress extrapolation detailed rules specified in the standards for the hotspot stress method.Originality/valueAdvanced dynamic analyses are proposed to obtain local stresses in order to apply a local method for the fatigue assessment of a bridge’s structure subjected to high-speed railway traffic on the basis of the mode superposition technique resulting in much less computing times.

Transient dynamic analysis of bars and trusses by the adaptive generalized finite element method

2019 ◽  
Vol 37 (3) ◽  
pp. 789-821
Author(s):  
Leticia Col Debella ◽  
Carolina Castro Cittadin ◽  
Marcos Arndt ◽  
Roberto Dalledone Machado
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Dynamic Analysis ◽  
Superposition Method ◽  
Generalized Finite Element Method ◽  
Transient Dynamic Analysis ◽  
Content Type ◽  
Modal Superposition Method ◽  
Modes Of Vibration ◽  
Element Method

Purpose This paper aims to present an adaptive approach of the generalized finite element method (GFEM) for transient dynamic analysis of bars and trusses. The adaptive GFEM, previously proposed for free vibration analysis, is used with the modal superposition method to obtain precise time-history responses. Design/methodology/approach The adaptive GFEM is applied to the transient analysis of bars and trusses. To increase the precision of the results and computational efficiency, the modal matrix is responsible for the decoupling of the dynamic equilibrium equations in the modal superposition method, which is used with only the presence of the problem’s most preponderant modes of vibration. These modes of vibration are identified by a proposed coefficient capable of indicating the influence of each mode on the transient response. Findings The proposed approach leads to more accurate results of displacement, velocity and acceleration when compared to the traditional finite element method. Originality/value In this paper, the application of the adaptive GFEM to the transient analysis of bars and trusses is presented for the first time. A methodology of identification of the preponderant modes to be retained in the modal matrix is proposed to improve the quality of the solution. The examples showed that the method has a strong potential to solve dynamic analysis problems, as the approach had already proved to be efficient in the modal analysis of different framed structures. A simple way to perform h-refinement of truss elements to obtain reference solutions for dynamic problems is also proposed.

An efficient method for seismic analysis of structures

2015 ◽  
Vol 32 (6) ◽  
pp. 1708-1721 ◽  
Author(s):  
A. Kaveh ◽  
H. Rahami ◽  
Iman Shojaei
Keyword(s):  
Finite Difference ◽  
Dynamic Analysis ◽  
Modal Analysis ◽  
Efficient Method ◽  
Seismic Analysis ◽  
Boundary Value ◽  
Efficient Solutions ◽  
Matrix Inversion ◽  
Graph Products ◽  
Content Type

Purpose – The purpose of this paper is to present an efficient method for dynamic analysis of structures utilizing a modal analysis with the main purpose of decreasing the computational complexity of the problem. In traditional methods, the solution of initial-value problems (IVPs) using numerical methods like finite difference method leads to step by step and time-consuming recursive solutions. Design/methodology/approach – The present method is based on converting the IVP into boundary-value problems (BVPs) and utilizing the features of the latter problems in efficient solution of the former ones. Finite difference formulation of BVPs leads to matrices with repetitive tri-diagonal and block tri-diagonal patterns wherein the eigensolution and matrix inversion are obtained using graph products rules. To get advantage of these efficient solutions for IVPs like the dynamic analysis of single DOF systems, IVPs are converted to boundary-value ones using mathematical manipulations. The obtained formulation is then generalized to the multi DOF systems by utilizing modal analysis. Findings – Applying the method to the modal analysis leads to a simple and efficient formulation. The laborious matrix inversion and eigensolution operations, of computational complexities of O(n2.373) and O(n3), respectively, are converted to a closed-form formulation with summation operations. Research limitations/implications – No limitation. Practical implications – Swift analysis has become possible. Originality/value – Suitability of solving IVPs and modal analysis using conversion and graph product rules is presented and applied to efficient seismic optimal analysis and preliminary design.

The effect of emotions, eWOM quality and online review sequence on consumer intention to follow advice obtained from digital services

2020 ◽  
Vol 31 (3) ◽  
pp. 465-487 ◽  
Author(s):  
Carla Ruiz-Mafe ◽  
Enrique Bigné-Alcañiz ◽  
Rafael Currás-Pérez
Keyword(s):  
Structural Model ◽  
Online Reviews ◽  
Moderating Effect ◽  
Online Information ◽  
Bias Effect ◽  
Content Type ◽  
Digital Services ◽  
Information Cues ◽  
Cognitive Information ◽  
The Impact

PurposeThis paper analyses the interrelationships between emotions, the cognitive information cues of online reviews and intention to follow the advice obtained from digital platforms, paying special attention to the moderating effect of the sequencing of review valence.Design/methodology/approachThe data were collected from 830 Spanish Tripadvisor users. In a two-step approach, a measurement model was estimated and a structural model analysed to test the proposed hypotheses. SmartPLS 3.0 software was used. The moderating effect of sequencing of reviews is tested.FindingsThe data analysis showed a bias effect of review sequence on the impact of online information cues and emotions on intention to follow advice obtained from Tripadvisor. When the online reviews of a restaurant begin with positive commentaries, their perceived persuasiveness is a stronger driver of the pleasure and arousal elicited by online reviews than when they begin with negative reviews. On the other hand, the perceived helpfulness of online reviews only triggers arousal when the user reads negative, followed by positive, comments. The impact of pleasure on intention to follow the advice provided in an online travel community is higher with positive-negative than with negative-positive sequences.Originality/valueWhile researchers have demonstrated the benefits of customer reviews on company sales, a largely uninvestigated issue is the interplay between emotions and cognitive information cues in the processing of online reviews. This is one of the first studies to examine the moderating effect of conflicting reviews on the impact of emotions and cognitive information cues on consumer intention to follow the advice obtained from digital services.

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