Fatigue Assessment of Steel-UHPC Lightweight Composite Deck Based on Multiscale FE Analysis: Case Study

2018 ◽  
Vol 23 (1) ◽  
pp. 05017015 ◽  
Author(s):  
Xudong Shao ◽  
Junhui Cao
Keyword(s):  
Fe Analysis ◽  
Fatigue Assessment

An Efficient Direct Calculation Approach for Fatigue Assessment of Container Ships Concerning Bending and Warping Stresses

2014 ◽  
Author(s):  
Zhiyuan Li ◽  
Wengang Mao ◽  
Jonas W. Ringsberg
Keyword(s):  
Beam Theory ◽  
Direct Calculation ◽  
Fe Analysis ◽  
Hydrodynamic Simulation ◽  
Fatigue Assessment ◽  
Hull Girder ◽  
Torsional Loads ◽  
Warping Stress

Container ships are particularly susceptible to torsional loads. The distribution of torsion-induced warping stress in a container ship hull is more complicated and difficult to be expressed by beam theory formulas. In practice, finite element (FE) analysis is typically used to calculate the stress response to wave-loading conditions. However, it is time consuming to compute hull girder stresses for all relevant sea conditions through FE analyses. In this paper, an efficient and robust approach is proposed by combining beam theory and FE analyses in the determination of hull girder stresses. The parameters required by beam theory can be regressed through matching stress records from a FE analysis with the corresponding sectional and pressure loads from the hydrodynamic simulation. Stress records obtained using the proposed method are utilized in fatigue assessment of a case study container vessel. The results show that the accuracy of the regression approach is satisfactory compared with the full FE analyses.

scholarly journals Structural Redundancy Assessment of Adjacent Precast Concrete Box-Beam Bridges in Service

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Yanling Leng ◽  
Jinquan Zhang ◽  
Ruinian Jiang ◽  
Yangjian Xiao
Keyword(s):  
Precast Concrete ◽  
Fe Analysis ◽  
Load Testing ◽  
Structural Redundancy ◽  
Simplified Approach ◽  
Box Beam ◽  
Nonlinear Fe Analysis ◽  
Redundancy Level ◽  
Real Behavior

Present approaches for assessing bridge redundancy are mainly based on nonlinear finite element (FE) analysis. Unfortunately, the real behavior of bridges in the nonlinear range is difficult to evaluate and a sound basis for the nonlinear FE analysis is not available. In addition, a nonlinear FE analysis is not feasible for practitioners to use. To tackle this problem, a new simplified approach based on linear FE analysis and field load testing is introduced in this paper to address the particular structural feature and topology of adjacent precast concrete box-beam bridges for the assessment of structural redundancy. The approach was first experimentally analyzed on a model bridge and then validated by a case study. The approach agrees well with the existing recognized method while reducing the computation complexity and improving the reliability. The analysis reveals that the level of redundancy of the bridge in the case study does not meet the recommended standard, indicating that the system factor recommended by the current bridge evaluation code for this bridge is inappropriate if considering the field condition. Further research on the redundancy level of this type of bridges is consequently recommended.

Fatigue Assessment of Work-Over Risers Through Physical Testing

2014 ◽  
Author(s):  
Gerhard Gundersen ◽  
Rolf Hugo Kirkvik ◽  
Christopher Hoen-Sorteberg
Keyword(s):  
Structural Response ◽  
Fe Analysis ◽  
Bending Test ◽  
Measurement Technology ◽  
Fatigue Assessment ◽  
Inner Work ◽  
Physical Testing ◽  
Bending Loads ◽  
Operational Criteria ◽  
Variable Internal Pressure

Critical sections of work over strings, with respect to integrity, are components located close to end terminations, near well heads and above drill floors, where recurring bending moments are prevalent. The lifetime of these components are strongly dependent on the stiffness in the components of the string. Connections between these components are often complex, and of a type where the stiffness is unknown, or hard to reveal based on theoretical analysis. This paper considers the feasibility of applying state-of-the-art measurement technology for testing of the physical behavior of specific connections on a landing string to be used for work over operations in harsh environmental conditions, where low fatigue life of components have proven to be a recurring problem. Behavior of joint-connections revealed through measured response from physical testing serve as input for the global finite element (FE) analysis, where accumulated fatigue damage for each sea state is calculated based on site specific met-ocean data. The present work was carried out in advance of an operation on the Norwegian shelf, where a four-point bending test of the actual landing string to be used during the offshore campaign were performed on a section containing two critical couplings, in order to reveal the actual stiffness of the connections. The test string was subject to variable internal pressure, axial tension and bending loads, representative for the applicable work-over riser operational loads. The performance of the system was monitored through strain, displacement and force sensors, in order to relate applied loads to structural response. The results from these tests where later recreated from local FE analysis, where non linear springs was implemented and modified to fit the experimental results at the connections of interest. These springs was later input to the global fatigue analysis, where the complete system, including marine riser and inner work over string, was implemented in one model. Results from the fatigue assessment where used to determine the operational criteria for the work over operations.

scholarly journals FE Analysis Of Meniscus Injury In A Square Stance Tennis Forehand Drive-a Case Study

2020 ◽  
Vol 52 (7S) ◽  
pp. 88-89
Author(s):  
Jingqiu Zhou ◽  
Hesheng Song ◽  
Jingguang Qian ◽  
Yu Liu ◽  
Hongwei Jiang ◽  
...  
Keyword(s):  
Fe Analysis ◽  
Meniscus Injury

scholarly journals Slopes Analyses - Case Study, Slope Stability of Bypass Project

2021 ◽  
Vol 4 (2) ◽  
pp. 34
Author(s):  
Diana Bardhi
Keyword(s):  
Fe Analysis ◽  
Parameter Study ◽  
Dilatancy Angle ◽  
Pressure Distributions ◽  
Strain Relationship ◽  
Simple Slope ◽  
Coulomb Model ◽  
The Difference ◽  
The Stability

The scope of this study was to compare various stability evaluation methods. Accordingly, most common LE approaches were compared with the advanced LE (M‐P) method. Similarly, the differences in FOS computed from LE and FE analyses were compared based on a simple slope considering various load cases. In addition, two real slopes in a case study were analysed for the recorded minimum‐maximum GWT, pseudo‐static and dynamic conditions. Moreover, the stability evaluations of these slopes were based on both LE (M‐P) and FE (PLAXIS) calculation approaches, which both utilized shear strength parameters from advanced triaxle tests. Similarly, Mohr‐Coulomb model was applied in both approaches. The following conclusions are hence derived based on the reported work on both idealized and real slopes. To fulfil one of the aims of the study, the LE based methods are compared based on the factor of safety (FOS) obtained for various load combinations. The comparison is mainly based on simplified slope geometry and assumed input parameters. Among the LE methods, the Bishop simplified (BS), Janbu simplified (JS) and Janbu GPS methods are compared with the Morgenstern‐Price method (M‐PM). These LE methods are well established for many years, and thus some of them are still commonly used in practice for stability analysis. Moreover, the M‐PM has been compared with results from the FE analyses. Compared with theFE (PLAXIS) analyses, the LE (M‐PM) analyses may estimate 5 – 14percent higher FOS, depending on the conditions of a dry slope and a fully saturated slope with hydrostatic pore pressure distributions. For fully saturated conditions in the slope, inaccurate computation of stresses in LE methods may have resulted in larger difference in the computed FOS. Since, the FE software is based on stress‐strain relationship, stress redistributions are surely better computed even for a complicated problem. This has been found one of the advantages in FE simulations. A parameter study shows that the application of a positive dilatancy angle in FE analysis can significantly improve the FOS (4 ‐ 10percent). On contrast, the shear surface optimization in LE (M‐PM in SLOPE/W) analysis results in lower FOS, and thus minimizing the difference in FOS compared with FE analysis

scholarly journals Localization of Simulated Damage on a Steel Beam from Random Vibrations

2017 ◽  
Vol 62 (1) ◽  
pp. 112
Author(s):  
Jan Bayer ◽  
Jaromír Král ◽  
Shota Urushadze
Keyword(s):  
Limit State ◽  
Fe Analysis ◽  
New Combination ◽  
Mode Shapes ◽  
Steel Beam ◽  
Ultimate Limit State ◽  
Air Stream ◽  
Localization Criterion ◽  
Ultimate Limit

The performance of a few localization schemes using measured mode shapes was tested in an experimental case study with respect to the Ultimate Limit State (ULS). The first question to be posed was: Is it possible to indicate and locate damage under laboratory conditions before the ULS is reached? Relatively simple localization criteria were chosen, which do not require extensive FE analysis. A new combination of them, designated here as Combined Localization Criterion (CLI), was proposed that performed well in the presented case. A simple supported beam with the damage progressing in three consecutive stages was used for the experiments. Mode shapes in the range of up to 100 Hz were extracted from the response of the structure to the air stream.

scholarly journals Environmental Fatigue Analysis of Nuclear Structural Components: Assessment Procedures, Loads, and a Case Study

Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 609
Author(s):  
Sergio Cicero ◽  
Thomas Metais ◽  
Yuliya Voloshyna ◽  
Sam Cuvillez ◽  
Sergio Arrieta ◽  
...  
Keyword(s):  
Real Data ◽  
Structural Components ◽  
Engineering Process ◽  
Specific Procedure ◽  
Fatigue Assessment ◽  
Different Types ◽  
Nuclear Component ◽  
Complex Engineering ◽  
Assessment Procedures

Nowadays, environmental fatigue assessment is mandatory in many countries, in the design and operational stages of nuclear structural components. The analysis of environmental fatigue can be a complex engineering process that is generally performed following national or international procedures. Such procedures are not always based on the same assumptions, and novel analysts may find a confusing variety of documents. Moreover, once a specific procedure has been chosen for the analysis, it is possible to complete the fatigue assessment by using design transients (and loads) or, alternatively, real loads provided by monitoring systems. In this context, this paper provides a comprehensive review of the different environmental fatigue assessment procedures and a brief description of the different types of load inputs (design vs. real data). The work is completed with a case study, in which the (fatigue) cumulative usage factor is estimated in a particular nuclear component by using one of the abovementioned assessment procedures (NUREG/CR-6909) and two options for the load inputs.

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