Titanium Riser Configurations

2002 ◽  
Author(s):  
Bernt J. Leira ◽  
Arve Bjo̸rset ◽  
Stig Berge
Keyword(s):  
Axial Force ◽  
Mechanical Design ◽  
Limit State ◽  
Local Buckling ◽  
Bending Moment ◽  
Relative Importance ◽  
Limit States ◽  
Characteristic Response ◽  
Riser Design ◽  
Critical Sections

The present paper addresses mechanical design aspects for titanium riser configurations. Three main types of riser systems are considered: • Vertical top-tensioned risers suspended from a TLP; • Catenary risers suspended from a TLP; • Pliant-wave risers suspended from a Semi-submersible. For each configuration, characteristic response properties related to bending moment and axial force diagrams are presented. Critical sections for each riser system are identified. For the vertical top-tensioned riser, design of a bending stiffener located at the seabed is briefly addressed. Capacity formulations and the relative importance of the following mechanical limit states are addressed: • Yielding; • Local buckling; • Fatigue. Differences between parameters influencing the various limit states for titanium respectively steel are highlighted. The local buckling limit state is subsequently focused upon in some more detail in relation to loads due to combined external overpressure and bending.

FEA of a Laminate Internal Buckle Arrestor for Deep Water Pipe-in-Pipe Flowlines

2009 ◽  
Author(s):  
Haoyu Wang ◽  
Jason Sun ◽  
Paul Jukes
Keyword(s):  
Deep Water ◽  
Mechanical Design ◽  
Limit State ◽  
Local Buckling ◽  
Design Parameters ◽  
Limit States ◽  
Element Analysis ◽  
Operational Lifetime ◽  
Buckle Propagation ◽  
Buckle Arrestors

Development of deepwater oil reservoirs has been undertaken in the Gulf of Mexico (GoM) where flowlines are installed in water depths in the vicinity of 2,740m (9,000ft). Preventing the propagation of local collapse/buckle failures is one of the key engineering design limit states that is defined in the industry codes to ensure the pipeline integrity. Deep-water buckle propagation is almost unavoidable as the wall thickness selection cannot be directly driven by the buckle propagation limit state. Field data indicates that once a buckle happens, the flowline could collapse for many kilometers instantly. Buckle propagation could cause substantial economic impact if left uncontrolled. For Pipe-in-Pipe (PIP) flowline, due to lack of pressure differential, the jacket pipe is a fragile component in terms of buckle propagation. It is crucial to prevent any possible local buckling during the flowline installation and during the entire operational lifetime. One way to stop buckle propagation is to utilize buckle arrestors of various types. Successfully designed buckle arrestors can contain such disasters to a limited pipeline section. Internal buckle arrestors are a relatively new solution for PIP systems being investigated by the industry. As it is installed in the annulus of PIP, it becomes a preferred choice since it fits all types of installation methods. The objective of this paper is to present the design and finite element analysis (FEA) of a laminate type internal buckle arrestor, and to investigate the effectiveness of this innovative buckle arrestor design for deepwater flowline. Sensitivities of key design parameters are explored with the purpose of guiding detailed mechanical design.

Combined flexure and torsion of I-shaped steel beams

1989 ◽  
Vol 16 (2) ◽  
pp. 124-139 ◽  
Author(s):  
Robert G. Driver ◽  
D. J. Laurie Kennedy
Keyword(s):  
Limit State ◽  
Bending Moment ◽  
Phase Behaviour ◽  
Inelastic Interaction ◽  
Steel Beams ◽  
Ultimate Limit State ◽  
Second Phase ◽  
Design Standards ◽  
Limit States ◽  
Interaction Diagram

Design standards provide little information for the design of I-shaped steel beams not loaded through the shear centre and therefore subjected to combined flexure and torsion. In particular, methods for determining the ultimate capacity, as is required in limit states design standards, are not presented. The literature on elastic analysis is extensive, but only limited experimental and analytical work has been conducted in the inelastic region. No comprehensive design procedures, applicable to limit states design standards, have been developed.From four tests conducted on cantilever beams, with varying moment–torque ratios, it is established that the torsional behaviour has two distinct phases, with the second dominated by second-order geometric effects. This second phase is nonutilizable because the added torsional restraint developed is path dependent and, if deflections had been restricted, would not have been significant. Based on the first-phase behaviour, a normal and shearing stress distribution on the cross section is proposed. From this, a moment–torque ultimate strength interaction diagram is developed, applicable to a number of different end and loading conditions. This ultimate limit state interaction diagram and serviceability limit states, based on first yield and on distortion limitations, provide a comprehensive design approach for these members. Key words: beams, bending moment, flexure, inelastic, interaction diagram, I-shaped, limit states, serviceability, steel, torsion, torque, ultimate.

Anchor rod forces and maximum bending moments in sheet pile walls using the factored strength approach

1996 ◽  
Vol 33 (5) ◽  
pp. 815-821 ◽  
Author(s):  
A B Schriver ◽  
A J Valsangkar
Keyword(s):  
Water Pressure ◽  
Limit State ◽  
Bending Moment ◽  
Ultimate Limit State ◽  
Sheet Pile ◽  
Limit States ◽  
Working Stress ◽  
Geotechnical Design ◽  
Ultimate Limit State Design ◽  
Sheet Pile Wall

Recently, the limit states approach using factored strength has been recommended in geotechnical design. Some recent research has indicated that the application of limit states design using recommended load and strength factors leads to conservative designs compared with the conventional methods. In this study the influence of sheet pile wall geometry, type of water pressure distribution, and different methods of analysis on the maximum bending moment and achor rod force are presented. Recommendations are made to make the factored strength design compatible with conventional design. Key words: factored strength, working stress design, ultimate limit state design, anchored sheet pile wall, bending moment, anchor rod force.

scholarly journals Reliability of Buried Pipes in Heterogeneous Soil Subjected to Seismic Loads

2021 ◽  
Vol 11 (1) ◽  
pp. 6708-6713
Author(s):  
H. Benzeguir ◽  
S. M. Elachachi ◽  
D. Nedjar ◽  
M. Bensafi
Keyword(s):  
Structural Reliability ◽  
Limit State ◽  
Bending Moment ◽  
Longitudinal Direction ◽  
Point Of View ◽  
Ultimate Limit State ◽  
Buried Pipe ◽  
Limit States ◽  
Ground Acceleration ◽  
Buried Pipes

Dysfunctions and failures of buried pipe networks, like sewer networks, are studied in this paper from the point of view of structural reliability and heterogeneity of geotechnical conditions in the longitudinal direction. Combined soil spatial variability and Peak Ground Acceleration (PGA) induce stresses and displacements. A model has been developed within the frame of geostatistics and a mechanical description of the soil–structure interaction of a set of buried pipes with connections resting on the soil by a two-parameter model (Pasternak model). Structural reliability analysis is performed considering two limit states: Serviceability Limit State (SLS), related to large "counter slope" in a given pipe, and Ultimate Limit State (ULS), corresponding to bending moment.

scholarly journals Stability of crane beam walls with fatigue cracksin the compressed belt zone

2020 ◽  
Vol 17 (4) ◽  
pp. 47-53
Author(s):  
A. E. Kubasevich ◽  
Keyword(s):  
Crack Length ◽  
Bearing Capacity ◽  
Critical Stress ◽  
Fatigue Cracks ◽  
Limit State ◽  
Bending Moment ◽  
Limit States ◽  
Stress Strain ◽  
Beam Bending ◽  
Stress Parameters

The paper describes a method for assessing the bearing capacity of the crane beam walls with fatigue cracks. There has been developed and implemented an algorithm for evaluating the stress-strain and limit state of the beam with a crack in the wall under a compressed belt. There has been established the dependence of the stress-strain and limit states of the beam wall on the value of the initial relative beam bending and the crack length in the section under the action of the bending moment and transverse force. The author presents the results of numerical studies of the effect of cracks on the bearing capacity of the beam wall. The influence of the amplitude of the initial beam wall deflection on the critical stress parameters is revealed. The dependence of the values of critical stress parameters on the relative crack length is considered.

DESIGN OF BOLTED CONNECTIONS SUBJECT TO TORSION AND SHEAR IN THE ULTIMATE LIMIT STRESS STATE

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Mohamed S. Abu-Yosef ◽  
Ezzeldin Y. Sayed-Ahmed ◽  
Emam A. Soliman
Keyword(s):  
Failure Modes ◽  
Focal Point ◽  
Design Method ◽  
Limit State ◽  
Bending Moment ◽  
Steel Structures ◽  
Ultimate Limit State ◽  
Shear Forces ◽  
Limit States ◽  
Ultimate Limit

Steel connections transferring axial and shear forces in addition to bending moment and/or torsional moment are widely used in steel structures. Thus, design of such eccentric connections has become the focal point of any researches. Nonetheless, behavior of eccentric connections subjected to shear forces and torsion in the ultimate limit state is still ambiguous. Most design codes of practice still conservatively use the common elastic analysis for design of the said connections even in the ultimate limit states. Yet, there are some exceptions such as the design method proposed by CAN/CSA-S16-14 which gives tabulated design aid for the ultimate limit state design of these connections based on an empirical equation that is derived for ¾ inch diameter A325 bearing type bolts and A36 steel plates. It was argued that results can also be used with a margin of error for other grade bolts of different sizes and steel of other grades. As such, in this paper, the performance of bolted connection subject to shear and torsion is experimentally investigated. The behavior, failure modes and factors affecting both are scrutinized. Twelve connections subject to shear and torsion with different bolts configurations and diameters are experimentally tested to failure. The accuracy of the currently available design equations proposed is compared to the outcomes of these tests.

Limit state behavior and response sensitivity analysis of endplate steel connections with shape memory alloy bolts

2020 ◽  
Vol 31 (18) ◽  
pp. 2071-2087
Author(s):  
Majid Mohammadi Nia ◽  
Saber Moradi
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Numerical Study ◽  
Slenderness Ratio ◽  
Limit State ◽  
Local Buckling ◽  
Limit States ◽  
Response Sensitivity ◽  
Cyclic Response ◽  
Steel Connections

Shape memory alloys have been used in developing self-centering steel moment connections. This article presents a numerical study aiming at evaluating the cyclic response sensitivity and limit states of extended endplate steel connections with shape memory alloy bolts. Three-dimensional finite element models are developed and validated against a recent experimental study. Using a statistical design-of-experiment method, the effects of 21 design factors and their interactions on the cyclic response of shape memory alloy connections are assessed. The sensitivity of six response parameters is studied. In addition, four limit states for shape memory alloy connections are discussed, including beam local buckling, bolt excessive axial strain, endplate yielding, and column flange yielding. Results show that endplate thickness, shape memory alloy bolt diameter, beam web slenderness ratio, and shape memory alloy maximum transformation strain are the most influential factors. Furthermore, endplate yielding is found to be the governing limit state in almost 80% of the analyzed connections, whereas shape memory alloy bolt excessive strain and column flange yielding are observed in less than 20% and 5% of the connections, respectively. Beam local buckling is not governing in the analyzed shape memory alloy connections designed as per the AISC 358-16 and AISC 341-16 seismic design requirements for extended endplate connections and highly ductile members.

scholarly journals Structural Reliability Analysis of Ship Hulls Accounting for Collision or Grounding Damage

2020 ◽  
Author(s):  
Branka Bužančić Primorac ◽  
Joško Parunov ◽  
C. Guedes Soares
Keyword(s):  
Reliability Analysis ◽  
Structural Reliability ◽  
Limit State ◽  
Random Variables ◽  
Bending Moment ◽  
State Equation ◽  
Limit States ◽  
Moment Capacity ◽  
Ship Hulls ◽  
Structural Reliability Analysis

AbstractClassical structural reliability analysis of intact ship hulls is extended to the case of ships with collision or grounding damages. Still water load distribution and residual bending moment capacity are included as random variables in the limit state equation. The probability density functions of these random variables are defined based on random damage parameters given by the Marine Environment Protection Committee of the International Maritime Organization, while the proposed reliability formulation is consistent with international recommendations and thus may be valuable in the development of rules for accidental limit states. The methodology is applied on an example of an Aframax oil tanker. The proposed approach captures in a rational way complex interaction of different pertinent variables influencing safety of damaged ship structure.

Reeling Analysis and Limit State Criteria

2016 ◽  
Author(s):  
Jianfeng Xu ◽  
Srinivas Vishnubhotla ◽  
Olav Aamlid ◽  
Leif Collberg
Keyword(s):  
Finite Element ◽  
Limit State ◽  
Local Buckling ◽  
Limit States ◽  
Fast Speed ◽  
Fatigue And Fracture ◽  
Different Types ◽  
Steel Catenary Risers ◽  
Fracture Performance ◽  
Limit State Criteria

Reeling has been an attractive offshore installation method for rigid flowlines and steel catenary risers due to its fast speed, cost effectiveness and reliability. Over years of evolution, it has become a proven technology, and the understanding to the engineering fundamentals is greatly improved as well. Due to the reeling process, the pipeline is plastically deformed; residual stresses, pipe ovality, and pipe out of straightness are increased. The strength, fatigue, and fracture performance of the pipe and the girth weld have to be closely evaluated to insure the pipeline integrity during and after the installation. As part of the installation design, different types of analyses are generally carried out to demonstrate the reelability, and the pipeline responses against all limit states. However, the methods adopted by different contractors can vary greatly. In this paper, the engineering fundamentals of reeling process are reviewed. A few typical reeling analyses, both analytical and finite element based, are demonstrated with examples. The local buckling limit state criteria based on DNV-OS-F101 for different stages of reeling are also illustrated.

Extreme Response Analysis of an End-Anchored Floating Bridge

2019 ◽  
Author(s):  
Zhengshun Cheng ◽  
Zhen Gao ◽  
Torgeir Moan
Keyword(s):  
Axial Force ◽  
Limit State ◽  
Bending Moment ◽  
Contour Method ◽  
Response Analysis ◽  
Ultimate Limit State ◽  
Extreme Response ◽  
Structural Responses ◽  
Floating Bridge ◽  
Extreme Responses

Abstract During the design of a floating bridge, extreme structural responses are required to be properly evaluated for ultimate limit state (ULS) design check. This study addresses the estimation of extreme structural responses for an end-anchored curved floating bridge. The floating bridge, about 4600 m, consists of a cable-stayed high bridge part and a pontoon-supported low bridge part. The long-term extreme responses are approximated by using a engineering approach, i.e., the environmental contour method. The sea state with 100-year environmental conditions is considered, and a 90% fractile is used to calculate the short-term extreme responses by using the Gumbel method and the mean up-crossing rate (MUR) method based on 100 1-hour simulations with different seeds. The extreme responses are expressed as μ + κσ, where μ and σ are the ensemble mean and standard deviation, and κ is a multiplying factor. Numerical results show that structural responses are close to Gaussian distributed. κ of axial force and strong axis bending moment along the bridge girder estimated by both the Gumbel and MUR methods vary in the vicinity of 4. κ estimated by the two method deviates, especially for axial force. Moreover, for both methods the estimated κ deviates more significantly if fewer ensembles are used.

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