Preloading Effects on the Behaviour of Cylindrical Members of Jacket Platforms Subjected to Ship Impact

2007 ◽  
Author(s):  
Maryam Abdolvahab ◽  
Mostafa Zeinoddini ◽  
Jafar Keyvani
Keyword(s):  
Numerical Study ◽  
Offshore Structures ◽  
Industrial Applications ◽  
Lateral Impact ◽  
Transverse Impact ◽  
Oil Platforms ◽  
Offshore Oil Platforms ◽  
Load Carrying ◽  
Loading Effects ◽  
The Impact

Steel tubes are widely encountered in industrial applications and in offshore structures. This is mostly because of their superior axial load carrying performance, low resistance against fluid loads and easy handling during construction and transportation. Cylindrical structural members, however, very often happen to become subject to accidental lateral damages which are detrimental to their load carrying performance. Collision between supply ships and legs and bracings of offshore oil platforms, impact from heavy dropped objects on these members or denting during installation of marine structures are examples of such accidents. Prior to an accident, cylindrical members are usually carrying their normal operational loads. It is very important to include the effects of this service load (pre-loading) in evaluation of the behaviour of impacted member. The pre-loading may change the dynamic characteristics of the member or degrade its load carrying capacity. While the performance of cylindrical members subjected to lateral impact has been extensively researched, few studies can be found on the impact behaviour of pre-loaded tubular members. This paper reports results from a numerical study on axial pre-loading effects on the dynamic and quasi-static behaviour of cylindrical shells subjected to transverse impact loads. Results obtained appear useful for a more realistic design of tubular members and in choosing feasible and reasonable post impact repairing and strengthening schemes.

scholarly journals Experimental and Numerical Study on Ultimate Shear Load Carrying Capacity of Corroded RC Beams

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Zhanzhan Tang ◽  
Zhixiang He ◽  
Zheng Chen ◽  
Lingkun Chen ◽  
Hanyang Xue ◽  
...  
Keyword(s):  
Shear Strength ◽  
Bearing Capacity ◽  
Cross Section ◽  
Loss Rate ◽  
Numerical Study ◽  
Rc Beams ◽  
Load Carrying ◽  
Shear Bearing Capacity ◽  
The Cross ◽  
The Impact

For an RC beam, the strength of steel rebar, the bonding strength between the concrete and reinforcement, and the bite action between the aggregates will deteriorate significantly due to corrosion. In the present study, 10 RC beams were designed to study the impact of corrosion on the shear bearing capacity. The mechanism of corrosion for stirrups and longitudinal bars and their effects were analyzed. Based on the existing experimental data, the correlation between the stirrup corrosion factor and the cross section loss rate was obtained. An effective prediction formula on the shear bearing capacity of the corroded RC beams was proposed and validated by the experimental results. Moreover, a numerical analysis approach based on the FE technique was proposed for the prediction of the shear strength. The results show that corrosion of the reinforcements could reduce the shear strength of the RC beams. The corrosion of stirrups can be numerically simulated by the reduction of the cross section. The formulae in the literature are conservative and the predictions are very dispersed, while the predictions by the proposed formula agree very well with the experiment results.

Experimental Investigation of Ice Mass Hydrodynamic Interaction With Offshore Structure in Close Proximity

2015 ◽  
Author(s):  
Tanvir Mehedi Sayeed ◽  
Bruce Colbourne ◽  
Heather Peng ◽  
Benjamin Colbourne ◽  
Don Spencer
Keyword(s):  
Hydrodynamic Interaction ◽  
Impact Load ◽  
Numerical Study ◽  
Numerical Models ◽  
Offshore Structures ◽  
Ocean Engineering ◽  
Offshore Structure ◽  
Area Of Interest ◽  
Close Proximity ◽  
The Impact

Iceberg/bergy bit impact load with fixed and floating offshore structures and supply ships is an important design consideration in ice-prone regions. Studies tend to divide the iceberg impact problem into phases from far field to contact. This results in a tendency to over simplify the final crucial stage where the structure is impacted. The authors have identified knowledge gaps and their influence on the analysis and prediction of iceberg impact velocities and loads (Sayeed et. al (2014)). The experimental and numerical study of viscous dominated very near field region is the main area of interest. This paper reports preliminary results of physical model tests conducted at Ocean Engineering Research Center (OERC) to investigate hydrodynamic interaction between ice masses and fixed offshore structure in close proximity. The objective was to perform a systematic study from simple to complex phenomena which will be a support base for the development of subsequent numerical models. The results demonstrated that hydrodynamic proximity and wave reflection effects do significantly influence the impact velocities at which ice masses approach to large structures. The effect is more pronounced for smaller ice masses.

scholarly journals EXPERIENCE OF USING GNSS MEASUREMENT RESULTS AT IGS STATIONS FOR MONITORING OFFSHORE OIL PLATFORMS ON THE SAKHALIN ISLAND

2019 ◽  
Vol 1 (1) ◽  
pp. 62-70
Author(s):  
Alexey Davydov ◽  
Elena Gienko
Keyword(s):  
Sea Of Okhotsk ◽  
Oil And Gas ◽  
Offshore Structures ◽  
Reference Points ◽  
Labor Protection ◽  
Oil Platforms ◽  
Offshore Oil Platforms ◽  
Measurement Results ◽  
Marine Platform ◽  
Offshore Oil

The article contains a description of the methodology for geodetic monitoring of offshore structures, on the example of the PA-B oil and gas platform located on the northeast shelf of Sakha-lin Island in the Sea of Okhotsk. Monitoring of dangerous industrial assets is crucial for the safe op-eration of the facility, labor protection and environmental. The assessment of the possibility of GNSS monitoring of the stationary marine platform with respect to IGS stations without the use of the coastal network of reference points, while maintaining the accuracy of the coordinates at the centimeter level is performed in the article. The results of experiments on processing GNSS meas-urements with respect to the network of IGS stations using the AUSPOS service are presented. It is shown that this method provides a centimeter level of accuracy and concluded that it can be used for monitoring of marine stationary platforms.

Numerical Study of Wave-Driven Impact of a Sea Ice Floe on a Circular Cylinder

2016 ◽  
Author(s):  
Biao Su ◽  
Karl Gunnar Aarsæther ◽  
David Kristiansen
Keyword(s):  
Numerical Model ◽  
Circular Cylinder ◽  
Sea Ice ◽  
Numerical Study ◽  
Offshore Structures ◽  
Experimental Result ◽  
Recent Experimental Study ◽  
Pressure Area ◽  
Closed Form Analytical Solution ◽  
The Impact

This paper presents a numerical model for simulating wave-driven ice floe–structure interactions, which is integrated in a software framework (FhSim) for time-domain simulation of marine systems. The FhSim framework has proved to be a valuable tool for research and development within different applications and areas [1]. In this study, the wave-driven impact of a sea ice floe on a circular cylinder is simulated. The simulation setup refers to a recent experimental study [2], and the kinematics of ice floe in wave is compared with the experimental result. As the impact forces were not measured in the experiment, a closed-form analytical solution proposed by ISO/FDIS 19906 (Arctic offshore structures) is used for comparison. These comparisons indicate that the present numerical model is able to reproduce the ice floe kinematics and impact characteristics during floe–structure interaction. Furthermore, a sensitivity analysis is conducted, aimed at investigating how much the simulated impact force is affected by variations in the pressure–area relationship.

Large Plastic Deformations of Beams Under Transverse Impact

1952 ◽  
Vol 19 (3) ◽  
pp. 308-314
Author(s):  
E. H. Lee ◽  
P. S. Symonds
Keyword(s):  
Plastic Flow ◽  
Permanent Deformation ◽  
Body Motion ◽  
Lateral Impact ◽  
Transverse Impact ◽  
Simple Method ◽  
Method Of Solution ◽  
Satisfactory Analysis ◽  
The Impact ◽  
Elastic Strains

Abstract A comparatively simple method of analysis is developed to determine the deformations in a beam subjected to lateral impact of such a magnitude that plastic strains large compared with elastic strains occur. A useful approximation to the motion then can be obtained by neglecting elastic strains and considering rigid-body motion of segments of the beam joined at plastic hinges where the entire deformation takes place. A method of analyzing such a situation is described and applied to a beam subjected to central impact. The approximate final permanent deformation is obtained; this includes deformation during application of the load, and plastic flow which continues afterward when the kinetic energy of the motion generated by the impact is transformed into additional plastic deformation. A criterion is given for conditions when this type of theory can be expected to provide a satisfactory analysis. The method of solution provides an interesting analogy to the concept of static determinacy which has been used in the analysis of quasi-static plastic-flow problems.

scholarly journals Telemedicine applied to offshore medical emergencies: impacts on a Brazilian oil industry

2021 ◽  
Vol 31 (Supplement_2) ◽  
Author(s):  
Douglas de Almeida Martins ◽  
Ana Carolina Braga Menezes ◽  
Vanessa Uchoa de Assis Martins da Silva ◽  
André Santana Costa ◽  
Maria Alzira Pimenta Dinis ◽  
...  
Keyword(s):  
Health Management ◽  
Reference Group ◽  
Operation Time ◽  
The Other ◽  
P Value ◽  
Contributing Factors ◽  
Oil Platforms ◽  
Offshore Oil Platforms ◽  
Medical Emergencies ◽  
The Impact

Abstract Background The study aims to analyse the impact of the use of advanced telemedicine resources in the management of medical emergencies on offshore oil platforms of a major Brazilian operator during the period 2018–2019. Methods 38 maritime platforms were analysed, totalling a sample of 5992 workers. Exploratory data analysis, adherence test to normal distribution (Ryan-Joiner normality test) and linear correlation test (Spearman’s rho) were used to characterize the data. 5 groups were defined, 1 offshore platform with advanced telemedicine resources (reference group) and 4 platforms without this support. Each group had data on the monthly amount of disembarkation due to health reasons, in 2018 and 2019, through common flights (1087 and 1207) and aeromedical evacuations (68 and 126), respectively. Finally, hypothesis testing was carried out for two independent samples, to compare the average landings of the reference group with the other groups. Results The reference group presented average landings for common flights lower than those of the other groups in 2018. In 2019, presented average landings for common flights lower than those of three groups and statistically equal to that of a group. In 2018 and 2019, the reference group presented statistically equal averages (P-value > α = 0.05) of landings due to aeromedical evacuations. Conclusions Despite the possibility of other contributing factors, such as health management of each group and operation time of the platforms, this study allows us to conclude that, in 2018 and 2019, the group of maritime platforms with advanced telemedicine resources obtained, in general, lower average landings due to health reasons.

scholarly journals Experimental and numerical study of axially-loaded RC columns and frame columns under lateral impact loading

2021 ◽  
Author(s):  
Zheng Luo ◽  
Wang Yinhui
Keyword(s):  
Impact Load ◽  
Numerical Study ◽  
Impact Resistance ◽  
Impact Excitation ◽  
Lateral Impact ◽  
Axial Loads ◽  
Free Standing ◽  
Positive Role ◽  
The Moment ◽  
The Impact

The pendulum impact tests were carried out on one RC frame column and four RC free-standing columns. The effect of axial compression ratio and reinforcement ratio on the impact resistance of columns were compared by means of dynamic time curves of framed and freestanding columns under impact. The test results show that with the same impact load, though the presence of axial loads can play a positive role (e.g., reducing the residual displacement), it may lead to more severe local damage. Also, compared with free-standing columns, the frame column can be considered as a protective structure for its greater lateral stiffness and stronger crashworthiness. The corresponding finite element models are developed，and the influence of the axial loads on cross section force responses under impact excitation is deeply explored. The axial loads can significantly affect the distribution of the moment, the shear force, and also the damage for the column.

Numerical Trials for the Soil-Spudcan Interface of Self-Elevating Units

2020 ◽  
Author(s):  
F. Alegre ◽  
J. Logarzo ◽  
S. Alibakhshi ◽  
A. Achard
Keyword(s):  
Analytical Calculation ◽  
Offshore Structures ◽  
Rigid Bodies ◽  
Arbitrary Lagrangian Eulerian ◽  
Oil Platforms ◽  
Offshore Oil Platforms ◽  
Linear Behavior ◽  
Wide Range ◽  
Deformable Bodies ◽  
Offshore Oil

Abstract This paper describes the development of a numerical model of a jack-up leg supported on the seabed and the study performed in order to analyze the interaction at the interface between the soil and its spudcan. Self-elevating units or jack-ups are widely used for offshore operations and the strength of their whole structure is to be ensured for the environmental conditions encountered during the operations. This is why the determination of the soil-spudcan interface is a major challenge since it depends on a wide range of factors, such as sea conditions, properties of the soil, geometry and material of the structure, etc. In light of the unpredictable and non-linear behavior of the marine environment and the soil, it is necessary to develop further studies on this subject to reduce uncertainties and to ensure the safety of offshore structures, as most of the failures in the offshore oil platforms are related to foundations. To do so, different approaches have been used: • Abaqus/ Standard and Abaqus/Explicit solvers; • Rigid bodies and deformable bodies afterwards; • Three kind of meshes: ○ Lagrangian mesh; ○ Arbitrary Lagrangian - Eulerian mesh; ○ Coupled Eulerian - Lagrangian mesh. To validate the model and the results obtained numerically in the end of the project, a comparison with an analytical calculation of the spudcan penetration has to be performed, based on the geometry of the structure and the properties of the soil.

scholarly journals Smoothing additive manufactured parts using ns-pulsed laser radiation

2021 ◽  
Author(s):  
Florian Kuisat ◽  
Fernando Lasagni ◽  
Andrés Fabián Lasagni
Keyword(s):  
Surface Roughness ◽  
Mechanical Performance ◽  
State Of The Art ◽  
Pulsed Laser ◽  
Industrial Applications ◽  
Laser Source ◽  
Pulsed Laser Radiation ◽  
Current State ◽  
The Impact

AbstractIt is well known that the surface topography of a part can affect its mechanical performance, which is typical in additive manufacturing. In this context, we report about the surface modification of additive manufactured components made of Titanium 64 (Ti64) and Scalmalloy®, using a pulsed laser, with the aim of reducing their surface roughness. In our experiments, a nanosecond-pulsed infrared laser source with variable pulse durations between 8 and 200 ns was applied. The impact of varying a large number of parameters on the surface quality of the smoothed areas was investigated. The results demonstrated a reduction of surface roughness Sa by more than 80% for Titanium 64 and by 65% for Scalmalloy® samples. This allows to extend the applicability of additive manufactured components beyond the current state of the art and break new ground for the application in various industrial applications such as in aerospace.

scholarly journals Oil and Flower Production in Rosa damascena trigintipetala Dieck under Salinity Stress in Taif Region, Saudi Arabia

2021 ◽  
Vol 13 (8) ◽  
pp. 4547
Author(s):  
Mohamed E. El-Sharnouby ◽  
Metwally M. Montaser ◽  
Sliai M. Abdallah
Keyword(s):  
Essential Oil ◽  
Essential Oils ◽  
Salinity Stress ◽  
Growth Parameters ◽  
Industrial Applications ◽  
Rosa Damascena ◽  
Flower Production ◽  
Survival Percentage ◽  
The Impact ◽  
Tolerance To Salinity

The flower industry depends on oil and fragrance, which is addressed in the current work. Different concentrations of NaCl (0, 250, 500, 1000, and 1500 ppm) were applied to Taif rose plants (Rosa damascena var. trigintipetala Dieck) to evaluate their effects on growth and essential oil content. Results clearly indicated the highest survival percentage (98.3%) was seen in untreated plants compared to plants under salinity stress. Moreover, increasing the NaCl levels induced an adverse effect on the growth parameters of Taif rose plants, while some essential oil contents were increased to the maximum degree of their tolerance to salinity stress. The extracted essential oils were analyzed using GC/MS. The essential oils of Taif rose plants treated with 500 ppm NaCl recorded the highest values of citronellol, geraniol and phenylethyl alcohol contents (16.56, 8.67 and 9.87%), respectively. NaCl at 250 ppm produced the highest values of heneicosane (13.12%), and then decreased to the lowest value (7.79%) with the increase of NaCl to 1500 NaCl, compared to the control and other NaCl levels. The current results could highlight the impact of salinity stress on Rosa damascena Miller var. trigintipetala Dieck for better economic and industrial applications.

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