Performance-Based Assessment of a Guyed Incinerator Stack Using Field Measurements

2020 ◽  
Author(s):  
Kenny T. Farrow ◽  
Jaideep Karmakar ◽  
Kannan Subramanian
Keyword(s):  
Lateral Displacement ◽  
Structural Response ◽  
Field Measurements ◽  
Element Model ◽  
Thermal Growth ◽  
Performance Based Assessment ◽  
Level 3 ◽  
Cooling Effects ◽  
Fema 356 ◽  
Guy Wires

Abstract ASME STS-1 provides guidelines for the design, fabrication, and erection of steel stacks, however there are no specific guidelines for the assessment of guyed steel stacks already in service. For example, drift (i.e., displacement) acceptance criteria are only provided for initial installation. Furthermore, existing literature regarding the proper re-tensioning of guy wires is scarce or nonexistent. This procedure is particularly important for stacks that experience significant thermal growth. This effect is further exacerbated by differential wind cooling effects on both the guy wires and on the stack itself. This paper investigates the effect of guy wire spacing, position, tension pattern, and operating and shutdown tension settings on the structural response of a guyed steel stack. Field thermography readings, ultrasonic testing (UT) thickness data, guy wire tension measurements, and laser scans are used to refine a finite element model of the stack. Using elastic-plastic nonlinear “pushover” analyses based on API 579 – 1 Level 3 fitness-for-service methodology and FEMA 356 rehabilitation guidelines, a performance-based methodology resulting in a “watch circle” approach for lateral displacement is provided to guide fitness-for-service assessments and mitigation implementation. Example application of this methodology and recommendations regarding guy wire tensioning are provided for an incinerator stack with 9 guy wires (3 levels – 3 guy wire configuration).

scholarly journals Response of the Flat Reinforced Concrete Floor Slab with Openings under Cyclic In-Plane Loading

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Eden Shukri Kalib ◽  
Yohannes Werkina Shewalul
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Lateral Displacement ◽  
Load Capacity ◽  
Element Model ◽  
Absorption Capacity ◽  
Hysteretic Behavior ◽  
Element Analysis ◽  
Floor Slab ◽  
Floor Slabs

The responses of flat reinforced concrete (RC) floor slabs with openings subjected to horizontal in-plane cyclic loads in addition to vertical service loads were investigated using nonlinear finite element analysis (FEA). A finite element model (FEM) was designed to perform a parametric analysis. The effects of opening sizes (7%, 14%, 25%, and 30% of the total area of the slab), opening shapes (elliptical, circular, L-shaped, T-shaped, cross, and rectangular), and location on the hysteretic behavior of the floor slab were considered. The research indicated that openings in RC floor slabs reduce the energy absorption capacity and stiffness of the floor slab. The inclusion of 30% opening on the floor slab causes a 68.5%, 47.3%, and 45.6% drop in lateral load capacity, stiffness, and lateral displacement, respectively, compared to the floor slab with no openings. The flat RC floor slab with a circular opening shape has increased efficiency. The placement of the openings is more desirable by positioning the openings at the intersection of two-column strips.

Generalised Beam Theory for composite beams with longitudinal and transverse partial interaction

2016 ◽  
Vol 22 (10) ◽  
pp. 2011-2039 ◽  
Author(s):  
Gerard Taig ◽  
Gianluca Ranzi
Keyword(s):  
Structural Response ◽  
Beam Theory ◽  
Element Model ◽  
Composite Beams ◽  
Cross Sectional ◽  
Shear Connections ◽  
Dynamic Analyses ◽  
Partial Interaction ◽  
Deformation Modes ◽  
Generalised Beam Theory

This paper presents a Generalised Beam Theory formulation to study the partial interaction behaviour of two-layered prismatic steel–concrete composite beams. The novelty of the proposed approach is in its capacity to handle the deformability of the shear connections at the interface between the slab and steel beam in both the longitudinal and transverse directions in the evaluation of the deformation modes. This method falls within a category of cross-sectional analyses available in the literature for which a suitable set of deformation modes, including conventional, extension and shear, is determined from dynamic analyses of discrete planar frame models representing the cross-section. In this context, the shear connections are modelled using shear deformable spring elements. As a result, the in-plane partial shear interaction behaviour is accounted for in the planar dynamic analysis during the evaluation of the conventional and extension modes, while the longitudinal partial interaction behaviour associated with the shear modes is included in the out-of-plane dynamic analyses. In the case of the conventional modes, the longitudinal slip is accounted for in the post-processing stage where the warping displacements are determined. A numerical example of a composite box girder beam is presented and its structural response investigated for different levels of shear connection stiffness in both the longitudinal and transverse directions. The accuracy of the numerical results is validated against those obtained with a shell finite element model implemented in ABAQUS/Standard software.

Optimization of Aircraft Mid-Fuselage Structure Design Based on Parametric Modeling

2014 ◽  
Vol 933 ◽  
pp. 423-427 ◽  
Author(s):  
Chao Ying Zhang ◽  
Hu Liu ◽  
Yun Peng Ma
Keyword(s):  
Structural Response ◽  
Aircraft Design ◽  
Element Model ◽  
Parametric Model ◽  
Structure Design ◽  
Parametric Modeling ◽  
Secondary Development ◽  
Typical Structure ◽  
Development Technology ◽  
Cae Technology

In aircraft preliminary design, fuselage structure design is important, and to reach the lightest weight is the main target for aircraft design, especially for civil aircraft. Based on CAD/CAE technology, the paper selects a typical structure layout form of aircraft mid-fuselage to study the method of structure model quickly creation and optimization. First, it focuses on fuselage parameterized modeling method, based on CATIA secondary development technology, to create the mid-fuselage parametric model. Then, based on Patran command language, the CAD model achieves automatic meshing. Finally, selecting an appropriate strategy and using iSIGHT integrated with fuselage parametric model and finite element model, and referring to the calculated the structural response by Nastran to realize mid-fuselage structure optimization.

Performance-Based Assessment of an Incinerator Stack Using Field Measurements

2021 ◽  
Author(s):  
Kenny Farrow ◽  
Jaideep Karmakar ◽  
Kannan Subramanian
Keyword(s):  
Field Measurements ◽  
Performance Based Assessment

Finite Element Modeling and Advanced Imaging by Instrumented Tap Testing

1999 ◽  
Author(s):  
V. Dayal ◽  
Tanveer A. Choudhary ◽  
D. K. Hsu ◽  
J. J. Peters ◽  
D. J. Barnard
Keyword(s):  
Finite Element ◽  
Structural Response ◽  
Element Model ◽  
Force Response ◽  
Honeycomb Core ◽  
Advanced Imaging ◽  
Tap Test ◽  
Main Emphasis ◽  
Non Destructive ◽  
Composite Face

Abstract Tap test is a very trusted and well used technique for the non-destructive evaluation of composite materials. Conventionally, a coin has been used for the tapping and the inspector listens to the resulting sound. The more advanced force response provides a number which can be correlated to the damage. A finite element model of the test has been developed with full honeycomb features and a dynamic tap is applied. The goal is to measure the reduction in stiffness of the structure due to simulated defects. This could be useful to both the manufacturer, as well as the user, to know the change in the structural response of the structure for a possible pass/fail criteria. We will also present results of an instrumented tap test with scanner. The main emphasis is on the testing of honeycomb core with composite face sheet panels. The results presented show the sensitivity of the tap test on simulated defects in honeycomb panels.

Evaluating the Effects of Ovality on the Integrity of Pipe Bends

2012 ◽  
Author(s):  
Chris Alexander
Keyword(s):  
Field Measurements ◽  
Element Analysis ◽  
Rigorous Evaluation ◽  
Pipe System ◽  
Extensive Evaluation ◽  
Assessment Approach ◽  
Level 3 ◽  
Multi Level ◽  
Engineering Investigation ◽  
Level 2

This paper provides details on a study performed for a liquids pipeline operator to evaluate the effects of ovality on the mechanical integrity of pipe bends in their 16-inch pipe system. Prior to this study, a caliper tool was run that indicated unacceptable ovality was present in the bends relative to the requirements set forth in ASME B31.4. An engineering investigation was performed based on the methodology of API 579 Fitness for Service. This standard provides guidance on evaluating defects using a multi-level assessment approach (Levels 1, 2, and 3) that rewards rigorous evaluation efforts by reducing the required design margins. Therefore, an extensive evaluation was performed that involved making field measurements of the bends in the ditch. Using these ovality measurements, calculations were performed using the closed-form equations in API 579 for Level 2 assessment. The ovality of several of the bends in the field was deemed unacceptable based on in-field measurements. Consequently, a Level 3 assessment was completed using finite element analysis (FEA). The results of this more rigorous analysis, coupled with more favorable design margins, resulted in this particular bend being acceptable. A tool was developed to permit a general assessment of pipe bends having ovality and was validated by performing a full-scale burst test.

Evaluation of the CSR-H Sloshing Criterion Using Direct Fluid Structure Calculation

2015 ◽  
Author(s):  
Po-Wen Wang ◽  
Chi-Fang Lee ◽  
Yann Quéméner ◽  
Chien-Hua Huang
Keyword(s):  
Finite Element ◽  
Fluid Dynamic ◽  
Plate Thickness ◽  
Structural Response ◽  
Element Model ◽  
Dynamic Responses ◽  
Interaction Technique ◽  
Time Step ◽  
Fluid Structure ◽  
Structural Rules

The objective of this study was to clarify the theoretical basis of sloshing loads and required plate thickness formulations in the harmonized common structural rules. This study used computational fluid dynamic (CFD) to calculate sloshing loads and used finite element analyses (FEA) to evaluate structural response. The sensitivity of the CFD predictions to the time step and grid size was also investigated. Cargo oil tanks were then selected in a handy size oil tanker and a very large crude carrier to evaluate the longitudinal and transverse sloshing loads on the tank boundaries. The results showed that the sloshing pressures computed at four filling levels were mostly consistent with CSR-H. Afterward, the sloshing pressure produced by CFD was applied to the finite element model by using a fluid-structure interaction technique to obtain the dynamic response of the structure. The dynamic responses were investigated to validate the quasistatic approach for sloshing assessment.

scholarly journals The physical impact of towed demersal fishing gears on soft sediments

2015 ◽  
Vol 73 (suppl_1) ◽  
pp. i5-i14 ◽  
Author(s):  
F. G. O'Neill ◽  
A. Ivanović
Keyword(s):  
Mathematical Modelling ◽  
Large Scale ◽  
Lateral Displacement ◽  
Field Measurements ◽  
Small Scale ◽  
Physical Interaction ◽  
Soft Sediments ◽  
Fishing Gears ◽  
Scale Modelling ◽  
Physical Impact

Abstract An improved understanding of the physical interaction of towed demersal fishing gears with the seabed has been developed in recent years, and there is a clearer view of the underpinning mechanical processes that lead to the modification and alteration of the benthic environment. The physical impact of these gears on soft sediments can be classified broadly as being either geotechnical or hydrodynamic in nature: penetration and piercing of the substrate, lateral displacement of sediment, and the influence of the pressure field transmitted through the sediment can be considered geotechnical, whereas the mobilization of sediment into the water column can be considered hydrodynamic. A number of experimental and numerical approaches have been used to gain better insights of these physical processes. These include small-scale modelling in towing tanks and sand channels; large-scale modelling in the field; measurements behind full-scale towed gears at sea; numerical/mathematical modelling of sediment mechanics; and numerical/mathematical modelling of hydrodynamics. Here, we will review this research, and that in associated fields, and show how it can form the basis of predictive models of the benthic impact of trawl gears.

Impact and Bandgap Characteristics of Periodic Rods With Viscoelastic Inserts and Local Resonators

2020 ◽  
Vol 143 (4) ◽  
Author(s):  
Y. Alsaffar ◽  
O. Aldraihem ◽  
A. Baz
Keyword(s):  
Finite Element ◽  
Impact Loading ◽  
Complex Modulus ◽  
Structural Response ◽  
Element Model ◽  
One Dimensional ◽  
Theoretical Predictions ◽  
Finite Element Package ◽  
Viscoelastic Composites ◽  
First Time

Abstract A comprehensive theoretical and experimental study is presented of the bandgap behavior of periodic viscoelastic material (VEM) composites subjected to impact loading. The composites under consideration consist of an assembly of aluminum sections integrated with periodic inserts which are arranged in one-dimensional configurations. The investigated inserts are manufactured either from VEM only or VEM with local resonators (LR). A finite element model (FEM) is developed to predict the dynamics of this class of VEM composites by integrating the dynamics of the solid aluminum sections with those of VEM using the Golla-Hughes-Mctavish (GHM) mini-oscillator approach. The integrated model enables, for the first time, the accurate predictions of the bandgap characteristics of periodic viscoelastic composites unlike previous studies where the viscoelastic damping is modeled using the complex modulus approach with storage modulus and loss factor are assumed constants and independent of the frequency or the unrealistic and physically inaccurate Kelvin–Voigt viscous-damping models. The predictions of the developed FEM are validated against the predictions of the commercial finite element package ansys. Furthermore, the FEM predictions are checked experimentally using prototypes of the VEM composites with VEM and VEM/LR inserts. Comparisons are also established against the behavior of plain aluminum rods in an attempt to demonstrate the effectiveness of the proposed class of composites in mitigation of the structural response under impact loading. Close agreements are demonstrated between the theoretical predictions and the obtained experimental results.

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