Fatigue and Ultimate Limit State of Grouted Tubular Joints

2002 ◽  
Author(s):  
Darren J. Morahan ◽  
Minaz Lalani
Keyword(s):  
Large Scale ◽  
Limit State ◽  
Cost Effective ◽  
Ultimate Limit State ◽  
Tubular Joints ◽  
Detail Design ◽  
Double Skin ◽  
Load Tests ◽  
Two Phases ◽  
Ultimate Limit

A joint industry project commenced in 1993 to develop a design manual for tubular joints, which are strengthened or repaired through chord grout filling. This project was carried out in two phases and was completed in the late 1990’s. The project comprised the conduct of over 200 SCF and ultimate load tests on large scale as-welded and grouted tubular joints. In addition to the testing programme, studies on offshore deployment were carried out to ensure that complete chord grout filling was achievable for all practical scenarios. The primary reason for carrying out this project is the industry-wide recognition that chord grout filling represents an extremely cost-effective and mechanically efficient method to strengthen or repair tubular joints. Further, it has been recognised that double-skin joints (e.g. pile through leg with annulus grout-filled) are often present in structures and the enhanced strength and fatigue characteristics as a result could be exploited to permit more efficient new platform designs or better estimation of joint performance for existing installations. Although API RP2A [1] and ISO [2] recommendations permit the use of grouted joints, little guidance is provided. The guidance that is provided is based on public domain data and engineering principles. This project was carried out to generate a substantial amount of new data/information, leading to the creation of a detail design manual for grouted joints [3,4].

scholarly journals A Comparative Study between Three-Legged and Tripod Sub-structures in Design of Offshore Wind Turbines in the Transition Water Depth

2018 ◽  
Vol 7 (3.36) ◽  
pp. 23
Author(s):  
Aliakbar Khosravi ◽  
Tuck Wai Yeong ◽  
Mohammed Parvez Anwar ◽  
Jayaprakash Jaganathana ◽  
Teck Leong Lau ◽  
...  
Keyword(s):  
Water Depth ◽  
Limit State ◽  
Cost Effective ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Ultimate Limit State ◽  
Offshore Wind Turbines ◽  
Welding Joints ◽  
Fatigue Limit State ◽  
Ultimate Limit

This research aimed at investigating tripod and three-legged offshore wind turbine substructures. A comparison between the two substructures based on their weight as well as the installation method of piles, i.e. pre-piling and post-piling, was carried out. The in-place (Ultimate Limit State), Dynamic, natural frequency check and fatigue (Fatigue Limit State) analyses were conducted considering aerodynamic and hydrodynamic loads imposed on substructures in 50m water depth. An optimisation process was carried out in order to reduce the mass of substructures. The results revealed that the three-legged substructure is more cost effective with 25% lesser structure mass. However, the construction of the three-legged structure usually takes more time due to increased number of members and subsequently welding joints. The results, furthermore, showed that the pre-piling method reduces the time and cost of offshore installation, and reduces the weight of piles by 50%.  

scholarly journals Reliability-Based Ultimate Limit State Design of Micropiles in Ontario Soils

2021 ◽  
Author(s):  
Alexandre P. R. P. Almeida
Keyword(s):  
Bond Strength ◽  
Failure Load ◽  
Limit State ◽  
Accurate Estimation ◽  
Ultimate Limit State ◽  
Resistance Factors ◽  
Ground Conditions ◽  
Load Tests ◽  
Ultimate Limit State Design ◽  
Ultimate Limit

The design practice of micropiles in Ontario soils under the ultimate limit state was improved through both statistical and reliability analyses of a database of 40 micropile load tests. Micropile design is extremely dependent on engineering experience and judgement due to the lack of an accurate estimation of the bond strength. The FHWA manual of micropiles only provides wide ranges of bond strength in different ground conditions. Micropile load tests were conducted by Keller Foundations Ltd and collected for this study. From a statistical analysis, Fuller and Hoy’s method was selected as the best method to estimate the failure load from non-failed tests. Adjusted parameters were given to predict the bond strength of micropiles. A method was proposed to estimate the contributions from the cased length and the tip to the total resistance. In the end, a reliability analysis was conducted and the resistance factors were recalibrated.

New Data on the Fatigue and Ultimate Limit State of Grouted Tubular Joints

1996 ◽  
Author(s):  
D.J. Morahan ◽  
R.J. van Foeken ◽  
M. Lalani ◽  
J. Wardenier
Keyword(s):  
Limit State ◽  
Ultimate Limit State ◽  
Tubular Joints ◽  
Ultimate Limit

scholarly journals Interpretation of uplift pipeline-soil interaction behaviour using acoustic emission measurements

2021 ◽  
Author(s):  
Alister Smith ◽  
Giorgio Barone ◽  
Rene Wackrow ◽  
Richard Stanley
Keyword(s):  
Acoustic Emission ◽  
Stress Level ◽  
Large Scale ◽  
Deformation Behaviour ◽  
Limit State ◽  
Ultimate Limit State ◽  
Ground Failure ◽  
Soil Failure ◽  
Uplift Resistance ◽  
Ultimate Limit

The objective of this study was to develop quantitative acoustic emission (AE) interpretation for uplift pipeline-soil interaction behaviour, enabling early warning of serviceability and ultimate limit state failures in the field. A series of large-scale uplift experiments was performed on a steel pipe in sand with different burial depths (i.e., stress levels), and varying rates of deformation were imposed. A suite of AE parameters was compared with the pipe force and displacement behaviour. Image-based deformation measurements were used to monitor the soil displacement field. AE generation was proportional to the imposed stress level and pipe displacement rate and related to the evolution of the pipe/soil failure mechanism. Relationships have been quantified between AE generation and stress level (R2 values of 0.99), and between AE generation rate and pipe velocity (R2 values ranging from 0.95 to 0.98), enabling interpretation of accelerating deformation behaviour that accompanies progressive ground failure processes. An example interpretation framework demonstrates how AE parameters can be used to identify the mobilisation of peak uplift resistance and quantify accelerating deformation behaviour during post-peak softening.

scholarly journals Reliability-Based Ultimate Limit State Design of Micropiles in Ontario Soils

2021 ◽  
Author(s):  
Alexandre P. R. P. Almeida
Keyword(s):  
Bond Strength ◽  
Failure Load ◽  
Limit State ◽  
Accurate Estimation ◽  
Ultimate Limit State ◽  
Resistance Factors ◽  
Ground Conditions ◽  
Load Tests ◽  
Ultimate Limit State Design ◽  
Ultimate Limit

The design practice of micropiles in Ontario soils under the ultimate limit state was improved through both statistical and reliability analyses of a database of 40 micropile load tests. Micropile design is extremely dependent on engineering experience and judgement due to the lack of an accurate estimation of the bond strength. The FHWA manual of micropiles only provides wide ranges of bond strength in different ground conditions. Micropile load tests were conducted by Keller Foundations Ltd and collected for this study. From a statistical analysis, Fuller and Hoy’s method was selected as the best method to estimate the failure load from non-failed tests. Adjusted parameters were given to predict the bond strength of micropiles. A method was proposed to estimate the contributions from the cased length and the tip to the total resistance. In the end, a reliability analysis was conducted and the resistance factors were recalibrated.

Background to New Formulae for the Ultimate Limit State of Tubular Joints

1982 ◽  
Author(s):  
Colin J. Billington ◽  
Minaz Lalani ◽  
Ian E. Tebbett
Keyword(s):  
Limit State ◽  
Ultimate Limit State ◽  
Tubular Joints ◽  
Ultimate Limit

Background to New Formulas for the Ultimate Limit State of Tubular Joints

1984 ◽  
Vol 36 (01) ◽  
pp. 147-156 ◽  
Author(s):  
Colin J. Billington ◽  
Minaz Lalani ◽  
Ian E. Tebbett
Keyword(s):  
Limit State ◽  
Ultimate Limit State ◽  
Tubular Joints ◽  
Ultimate Limit
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