Combined Loading Criteria for Titanium Risers

2002 ◽  
Author(s):  
Olav Aamlid ◽  
Kristoffer Aronsen ◽  
Knut Olav Ronold ◽  
Kim Mo̸rk ◽  
Carl Baxter
Keyword(s):  
Axial Force ◽  
State Of The Art ◽  
Bending Moment ◽  
Uncertainty Modeling ◽  
Combined Loading ◽  
Design Equation ◽  
Data Basis ◽  
Load Effects ◽  
Calibration Study ◽  
Pipeline Design

DNV has, in cooperation with partners from the industry, carried out a joint industry project with the aim to develop recommended practice with respect to the design of titanium risers. As a part of this work, calibrated design formulae for combined loading have been established. The considered load situation is a combination of internal overpressure, bending moment and axial force. The data basis for the calibration study encompasses results from 12 finite element simulations with varying diameter to thickness ratio and internal pressure exposed to bending moment and axial force. With the design equation for steel risers, taken from the DNV Offshore Standard (OS-F201) Dynamic Risers, as a basis, the titanium data basis was investigated using state-of-the art methodology with an uncertainty modeling for load effects in compliance with recent research and development projects for risers and pipeline design. The outcome of this work is a design equation with reliability based calibration of safety factors that comply with the overall safety objective in the above offshore standard.

DNVGL-ST-F101 Combined Loading Criterion: Range of Application and Comparison With Other Criteria

2016 ◽  
Author(s):  
Olav Fyrileiv ◽  
Leif Collberg ◽  
Olav Aamlid
Keyword(s):  
Axial Force ◽  
Bending Moment ◽  
Design Criterion ◽  
Combined Loading ◽  
Moment Capacity ◽  
Offshore Pipeline ◽  
Global Buckling ◽  
Current Criterion ◽  
Set Up ◽  
Pipeline Design

The most essential pipeline design criterion is, of course, the pressure containment or bursting criterion normally determining the pipe wall thickness. When the pressure containment is ensured, the concern is often towards the action of the combined loading; pressure, axial force and bending moment. The combined loading criterion typically governs the installation and also set up requirements for other design issues such as seabed intervention and global buckling. The combined loading criterion of DNV GL submarine pipeline systems standard, DNV-OS-F101 or DNVGL-ST-F101 which is its new name [1], has been modified several times, and the current version was introduced in its present form in the 2007 revision of the offshore pipeline standard. This paper discusses the current criterion for combined loading, i.e. bending moment capacity, when the pipeline is under influence of axial force and internal over-pressure. The criterion is compared with several other similar criteria from previous revisions of the DNV GL pipeline and riser standards and from other offshore pipeline standards. In addition a comparison with physical and numerical tests is given, while the background and derivation of the criterion are given in an accompanying paper by Collberg and Levold [2].

Numerical Modeling and Dynamic Analysis of a Floating Bridge Subjected to Wind, Wave, and Current Loads

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Zhengshun Cheng ◽  
Zhen Gao ◽  
Torgeir Moan
Keyword(s):  
Axial Force ◽  
Wind Wave ◽  
Bending Moment ◽  
Wave Loads ◽  
Environmental Loads ◽  
Turbulent Wind ◽  
Load Effects ◽  
Floating Bridge ◽  
Bridge Girder ◽  
Sway Motion

Designing reliable and cost-effective floating bridges for wide and deep fjords is very challenging. The floating bridge is subjected to various environmental loads, such as wind, wave, and current loads. All these loads and associated load effects should be properly evaluated for ultimate limit state design check. In this study, the wind-, wave-, and current-induced load effects are comprehensively investigated for an end-anchored curved floating bridge, which was an early concept for crossing the Bjørnafjorden. The considered floating bridge is about 4600 m long and consists of a cable-stayed high bridge part and a pontoon-supported low bridge part. It also has a large number of eigen-modes, which might be excited by the environmental loads. Modeling of wind loads on the bridge girder is first studied, indicating that apart from aerodynamic drag force, aerodynamic lift and moment on the bridge girder should also be considered due to their significant contribution to axial force. Turbulent wind spectrum and spatial coherence play an important role and should also be properly determined. The sway motion, axial force, and strong axis bending moment of the bridge girder are mainly induced by wind loads, while the heave motion, weak axis bending moment, and torsional moment are mainly induced by wave loads. Turbulent wind can cause significant larger low-frequency eigen-mode resonant responses than the second-order difference frequency wave loads. Current loads mainly contribute damping and reduce the variations of sway motion, axial force, and strong axis bending moment.

The Influence of Loads Superposition, Deterioration Due to Cracks and Residual Stresses on the Strength of Tubular Junction

2017 ◽  
Vol 68 (6) ◽  
pp. 1267-1273
Author(s):  
Valeriu V. Jinescu ◽  
Angela Chelu ◽  
Gheorghe Zecheru ◽  
Alexandru Pupazescu ◽  
Teodor Sima ◽  
...  
Keyword(s):  
Stress Concentration ◽  
Residual Stresses ◽  
Bending Moment ◽  
Combined Loading ◽  
Torsional Moment ◽  
Calculation Methods ◽  
State Of Stress ◽  
Cracked Structures ◽  
Total Participation ◽  
Theoretical Results

In the paper the interaction of several loads like pressure, axial force, bending moment and torsional moment are analyzed, taking into account the deterioration due to cracks and the influence of residual stresses. A nonlinear, power law, of structure material is considered. General relationships for total participation of specific energies introduced in the structure by the loads, as well as for the critical participation have been proposed. On these bases: - a new strength calculation methods was developed; � strength of tubular cracked structures and of cracked tubular junction subjected to combined loading and strength were analyzed. Relationships for critical state have been proposed, based on dimensionless variables. These theoretical results fit with experimental date reported in literature. On the other side stress concentration coefficients were defined. Our one experiments onto a model of a pipe with two opposite nozzles have been achieved. Near one of the nozzles is a crack on the run pipe. Trough the experiments the state of stress have been obtained near the tubular junction, near the tip of the crack and far from the stress concentration points. On this basis the stress concentration coefficients were calculated.

scholarly journals Design and analysis of concrete-filled tubular flange girders under combined loading

2021 ◽  
pp. 136943322110015
Author(s):  
Rana Al-Dujele ◽  
Katherine Ann Cashell
Keyword(s):  
Finite Element ◽  
Axial Force ◽  
Failure Modes ◽  
Numerical Study ◽  
Combined Loading ◽  
Torsional Stiffness ◽  
Fe Model ◽  
Combined Effects ◽  
Element Analysis ◽  
Hollow Section

This paper is concerned with the behaviour of concrete-filled tubular flange girders (CFTFGs) under the combination of bending and tensile axial force. CFTFG is a relatively new structural solution comprising a steel beam in which the compression flange plate is replaced with a concrete-filled hollow section to create an efficient and effective load-carrying solution. These members have very high torsional stiffness and lateral torsional buckling strength in comparison with conventional steel I-girders of similar depth, width and steel weight and are there-fore capable of carrying very heavy loads over long spans. Current design codes do not explicitly include guidance for the design of these members, which are asymmetric in nature under the combined effects of tension and bending. The current paper presents a numerical study into the behaviour of CFTFGs under the combined effects of positive bending and axial tension. The study includes different loading combinations and the associated failure modes are identified and discussed. To facilitate this study, a finite element (FE) model is developed using the ABAQUS software which is capable of capturing both the geometric and material nonlinearities of the behaviour. Based on the results of finite element analysis, the moment–axial force interaction relationship is presented and a simplified equation is proposed for the design of CFTFGs under combined bending and tensile axial force.

Effect of Torsion on Collapse Bending Moment for 24-Inch Diameter Schedule 80 Pipes With Wall Thinning

2012 ◽  
Author(s):  
Kunio Hasegawa ◽  
Yinsheng Li ◽  
Bostjan Bezensek ◽  
Phuong Hoang
Keyword(s):  
Power Plants ◽  
Bending Moment ◽  
Combined Loading ◽  
Bending Moments ◽  
Compressive Stresses ◽  
Wall Thinning ◽  
Nominal Thickness ◽  
Calculation Results ◽  
Loading Modes ◽  
Local Wall Thinning

Piping items in power plants may experience combined bending and torsion moments during operation. Currently, there is a lack of guidance in the ASME B&PV Code Section XI for combined loading modes including pressure, torsion and bending. Finite element analyses were conducted for 24-inch diameter Schedule 80 pipes with local wall thinning subjected to tensile and compressive stresses. Plastic collapse bending moments were calculated under constant torsion moments. From the calculation results, it can be seen that collapse bending moment for pipes with local thinning subjected to tensile stress is smaller than that subjected to compressive stress. In addition, equivalent moment is defined as the root the sum of the squares of the torsion and bending moments. It is found that the equivalent moments can be approximated with the pure bending moments, when the wall thinning length is equal or less than 7.73R·t for the wall thinning depth of 75% of the nominal thickness, where R is the mean radius and t is the wall thickness of the pipe.

Prediction Method for Plastic Collapse of Pipes Subjected to Combined Bending and Torsion Moments

2010 ◽  
Author(s):  
Yinsheng Li ◽  
Kunio Hasegawa ◽  
Phuong H. Hoang ◽  
Bostjan Bezensek
Keyword(s):  
Entire Range ◽  
Estimation Method ◽  
Prediction Method ◽  
Bending Moment ◽  
Combined Loading ◽  
Plastic Collapse ◽  
Finite Element Analyses ◽  
Pure Torsion ◽  
Stainless Steel Pipe ◽  
Service Inspection

When a crack is detected in a pipe during in-service inspection, the failure estimation method given in the codes such as ASME Boiler and Pressure Vessel Code Section XI non-mandatory Appendix C or JSME S NA-1-2008 Appendix E-8 can be applied to assess the integrity of the pipe. In the current editions of these codes, the failure estimation method is provided for bending moment and pressure. Torsion load is assumed to be relatively small and is not considered in the method. In this paper, finite element analyses are conducted for 24-inch stainless steel pipe with a circumferential surface crack subjected to the combined bending and torsion moments, focusing on large and pure torsion moments. Based on the analysis results, a prediction method for plastic collapse under the combined loading conditions of bending and torsion is proposed for the entire range of torsion moments.

Closed-form moment-curvature relations for reinforced concrete cross sections under bending moment and axial force

2016 ◽  
Vol 129 ◽  
pp. 67-80 ◽  
Author(s):  
Pedro Dias Simão ◽  
Helena Barros ◽  
Carla Costa Ferreira ◽  
Tatiana Marques
Keyword(s):  
Reinforced Concrete ◽  
Closed Form ◽  
Axial Force ◽  
Cross Sections ◽  
Bending Moment

Preliminary Parametric Assessment of a Bolted Endplate Joint under Combined Axial Force and Cyclic Bending Moment

2011 ◽  
Vol 255-260 ◽  
pp. 718-721
Author(s):  
Z.Y. Wang ◽  
Q.Y. Wang
Keyword(s):  
Finite Element Analysis ◽  
Axial Force ◽  
Seismic Design ◽  
Axial Load ◽  
Failure Modes ◽  
Bending Moment ◽  
Element Analysis ◽  
Cyclic Behaviour ◽  
Joint Behaviour ◽  
Steel Joints

Problems regarding the combined axial force and bending moment for the behaviour of semi-rigid steel joints under service loading have been recognized in recent studies. As an extended research on the cyclic behaviour of a bolted endplate joint, this study is performed relating to the contribution of column axial force on the cyclic behaviour of the joint. Using finite element analysis, the deteriorations of the joint performance have been evaluated. The preliminary parametric study of the joint is conducted with the consideration of flexibility of the column flange. The column axial force was observed to significantly influence the joint behaviour when the bending of the column flange dominates the failure modes. The reductions of moment resistance predicted by numerical analysis have been compared with codified suggestions. Comments have been made for further consideration of the influence of column axial load in seismic design of bolted endplate joints.

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