Zafarullah Nizamani | Universiti Teknologi PETRONAS (original) (raw)
Papers by Zafarullah Nizamani
E3S Web of Conferences
Floods are one of the most damaging natural disasters which occur frequently in the world. They o... more Floods are one of the most damaging natural disasters which occur frequently in the world. They occur every year in Malaysia due to higher precipitation rates, river meandering, and heavily populated suburban areas. Monsoon rains are the major cause of floods and occur two times per year. The heavy floods in the Kelantan River Basin have shown an increasing trend in recent years. Terrain characteristics of the land and meteorological properties of the region are the main natural factors for this disaster. In this study, the Kuala Krai district of the Kelantan River is selected to be reviewed as the case study for flood risk analysis. Geographical Information System (GIS) integrated with Multicriteria Decision Analysis (MCDA) can be used to evaluate the potential flood risk areas. Historically flooded areas can be extracted from the satellite images to determine flood causing factors for the analysis. At the end of the study, a map of flood risk areas can be generated and validated t...
E3S Web of Conferences
Four reinforced concrete rooms are used in this study, with varying floor areas, openings, and fu... more Four reinforced concrete rooms are used in this study, with varying floor areas, openings, and fuel loads. These rooms are office, Classroom, computer, and chemical laboratories of institutional buildings. The time versus Eurocode (EC) parametric fire relationship is determined and compared with ISO 834 and ASTM 119. The performance of the slab is evaluated based on the EC target reliability index of 3.8 for 50 years design period using the First Order Reliability Method (FORM). The probability of failure and structural reliability of each fire compartment at different fire duration is determined. Variables used were concrete compressive strength, a reduction factor of concrete compressive strength, steel yield strength, concrete cover, slab depth, unit width, and area of steel reinforcement provided. The reliability is determined at each 30 minutes fire duration for all fire compartments. The starting point is ambient temperature, then after every thirty minutes until the time when...
Journal of Marine Science and Engineering, 2022
The behavior of different mooring line materials has a significant influence on the behavior of t... more The behavior of different mooring line materials has a significant influence on the behavior of the mooring system and, consequently, the dynamic responses of the floating platform. Although there have been previous studies on FPSOs and their mooring systems, the influence of mooring line failure scenarios associated with different mooring materials has received less attention, particularly for turret-moored FPSOs with taut moorings. Thus, this paper investigates the behavior of different mooring line materials in intact, single-line, and double-line damaged conditions on the hydrodynamic responses of the FPSO, restoring behavior, mooring, and riser tensions considering wave conditions in the Gulf of Mexico. Mooring lines including Aramid, HMPE, polyester, and steel wire were considered in the middle segment, which was the segment of interest in this study. The restoring forces of the mooring system were found to increase with increasing mooring stiffness, and a higher stiffness res...
IEEE Access, 2021
The Jacket platform needs gas and diesel to run its turbines, and in the end, they produce catast... more The Jacket platform needs gas and diesel to run its turbines, and in the end, they produce catastrophic emissions annually. The environmental concerns regarding these platforms have forced us to utilize an alternative source of energy that is sustainable and clean. In this study 51 locations, are of interest where oil and gas activities are in progress at present in the shape of a jacket platform or pipelines. The significant wave height and wave period scatter diagram data are collected from the platforms in the South China Sea. The linear wave theory is used to find the wave power. The given time period is converted into an equivalent time period first before wave energy is determined. The study shows that location no. 20 is the ideal location to deploy the wave energy converter Pelamis P2 with a potential mean wave power of 6.61 kW/m A single unit of Pelamis P2 can produce on an average electricity output of 91.37 kW/m including, the losses and machine efficiencies, whereas a wave farm can generate an average output of 62 GWh/ yr. The electricity supply of 70.3 % of the minimum and 14.1 % of the maximum energy demand, while using only wave energy converter. If hybrid wind and wave energy system is used, then energy production will increase. The results show that the wave farm could also reduce the use of natural gas up to 17.6E06 m 3 / year, avoiding the emission of 12000 tonnes of CO and 54000 tonnes of NOx annually, and can save up to RM 20 billion annually with the reduction of natural gas emissions. INDEX TERMS Wave energy converter, renewable energy, South China Sea, metocean, jacket platform.
A numerical method of predicting the turbulent mixing process of a treated sewer disposed from a ... more A numerical method of predicting the turbulent mixing process of a treated sewer disposed from a marine outfall is described. The momentum equations for the sea water mixed with treated water of small salinity and warmer temperature are solved numerically together with the equation of the concentration of the treated water. The basic method is a Large Eddy Simulation (LES) formulated on a fixed rectangular grid where boundaries are approximated by Immersed Boundary (IB) method. The sub-grid effects of the unresolved fluctuations of velocity and the concentration fields are expressed by the eddy viscosity and eddy diffusivity with the Smagorinsky model. The method is verified with an experiment and RANS calculation of the buoyant wall jet issuing on a solid surface. The method then is used to simulate the dispersion and dilution of the effluent from a typical marine outfall installed on the seabed of shallow coastal water. The behavior of the plume in the vicinity of the outfall is s...
Large eddy simulation of buoyant jet in shallow water Akihiko Nakayama, Jeremy D. Bricker and Zaf... more Large eddy simulation of buoyant jet in shallow water Akihiko Nakayama, Jeremy D. Bricker and Zafarullah Nizamani Department of Environmental Engineering, Universiti Tunku Abdul Rahman akihiko@utar.edu.my Abstract A numerical method of predicting the turbulent mixing process of disposed water from an outfall in a shallow coastal water is described. The momentum equations for the sea water mixed with treated water of small salinity and warmer temperature are solved numerically together with the equation of the concentration of the treated water. The basic method is a Large Eddy Simulation (LES) formulated on a fixed rectangular grid where boundaries are approximated by Immersed Boundary (IB) method. The sub-grid effects of the unresolved fluctuations of velocity and the concentration fields are expressed by the eddy viscosity and eddy diffusivity with the Smagorinsky model. The method is verified with an experiment and RANS calculation of the buoyant wall jet issuing on a solid surfa...
The effects of the surface waves generated by the wind have a significant effect on the currents.... more The effects of the surface waves generated by the wind have a significant effect on the currents. A wave current coupled model plays an important role in the design of offshore structures. The interaction between fluids such as incompressible ocean waves and current and offshore structures is significant with many real-time applications in offshore engineering. These coupled models can be applied to Offshore Floating Production Operating and offloading (FPSO), Wind or current turbines and offshore pipelines. The complex issues related to the design are analyzed by using Computational Fluid Dynamics, which requires an investigation of the multiphase flow between wave and current and the structure which is considered restrictive due to the computational cost. If viscous effects are neglected then the single-phase flow models have been recommended, where wave-current interaction have been modelled successfully. Models have been developed where velocities and pressure are computed and t...
CFD Letters, 2020
The effects of the surface waves generated by the wind have a significant effect on the currents.... more The effects of the surface waves generated by the wind have a significant effect on the currents. A wave current coupled model plays an important role in the design offshore structures. The interaction between fluids such as incompressible ocean waves and current and offshore structures is significant with many real-time applications in offshore engineering. These coupled models can be applied to Offshore Floating Production Operating and offloading (FPSO), Wind or current turbines and offshore pipelines. The complex issues related to the design are analyzed by using Computational Fluid Dynamics, which requires an investigation of the multiphase flow between wave and current and the structure which is considered restrictive due to the computational cost. If viscous effects are neglected then the single-phase flow models have been recommended, where wave-current interaction have been modelled successfully. Models have been developed where velocities and pressure are computed and the results can be verified with the experimental results available in the literature. In this study the existing numerical methods, mesh types are discussed along with their coupling methods. Here single-phase and multiphase models with small and medium movement are reviewed and their applications are highlighted. Commercial CFD code ANSYS Fluent has been found most reliable and easy to use tool for the analysis of fluid flow interacting with offshore structures near the free surface. It can successfully be used for determination of fluid dynamics of offshore environments installed complex multi-component structures. Dynamic mesh facility is more useful for multiphase modelling of floating structures.
MATEC Web of Conferences, 2018
Most of the residential buildings in Malaysia are not designed to withstand the seismic forces, w... more Most of the residential buildings in Malaysia are not designed to withstand the seismic forces, while the high-rise buildings. However, since the Sumatra 2004 earthquake, there had been increasing concerns about the structure vulnerability in our country to earthquakes. Several recent studies had also revealed that Malaysia had the possibility to be influenced by both local and far field earthquakes. This study is conducted to analyze the vulnerability of a high rise building to local and far field earthquakes using Scia Engineer. Modal Response Spectrum method of Scia Engineer is used. The model is a 12 story hotel building from Ipoh, Perak. The designing code is the Eurocode with Malaysia Annex. Different Peak Ground Accelerations (PGA) that represents the local and far field earthquakes is acted on the model to obtain the seismic performance. The deformation of the building by the seismic combinations is compared to the ASCE-7 design to evaluate the vulnerability. Research of sei...
INTERNATIONAL SYMPOSIUM ON GREEN AND SUSTAINABLE TECHNOLOGY (ISGST2019), 2019
The importance is given for the efficient design of offshore structures which should include econ... more The importance is given for the efficient design of offshore structures which should include economic and safety concerns. The properties of wind-generated (main) surface waves and currents are recognized to play a vital role during design of offshore structures such as windmills, fixed and floating structures. This study looks into the mechanisms of metocean forces, acting on these structures near the continental shelf region of Malaysia. At present, near offshore Malaysia, there is no real behaviour model available for currents and the interaction between waves and current. The free surface flow and rigid body interaction with structural issues of offshore structures such as fatigue, corrosion, and marine growth are also not researched in this region before. Therefore, current and wave-current models need to be developed using the finite volume method. Physics of these forces need to be determined and their free surface flow motions require the development of a framework. Fluidstructure interaction (FSI) is used to model the interfaces such as air-fluid (free surface) and fluid-structure (rigid-body). A Freesurface/rigid body problem fully coupled finite volume model is a preferred method. Six degree of freedom of motion equations are used to define the rigid body. This paper is based on literature review and the expected results due to the effects of wind on wave and currents and the mechanics of current are highlighted along with the seasonal effects of the current. To deal with the moving rigid body and the fluid domain interface an interface-tracking method is used.
MATEC Web of Conferences, 2017
Fluid structure interaction (FSI) applications are of wide range from offshore fixed and floating... more Fluid structure interaction (FSI) applications are of wide range from offshore fixed and floating structures to offshore pipelines. Reynolds Averaged Navier Stoke (RANS) solution has limitation for unsteady and turbulent flow modelling. A possible approach is Large Eddy Simulation (LES) and it is applied to flows past a circular cylinder located far above, near and on a flat seabed. The Reynolds number considered is based on the real situation off Malaysia Coast and is sub-critical around 105. Hydrodynamic quantities in terms of mean pressure are predicted and vortex shedding mechanism is evaluated. The results are validated by comparing the simulation and experimental previous studies.
MATEC web of conferences, 2017
Metocean environmental load includes wind, wave and currents. Offshore structures are designed fo... more Metocean environmental load includes wind, wave and currents. Offshore structures are designed for two environmental load design conditions i.e. extreme and operational load conditions of environmental loads are evaluated. The ccorrelation between load variables using Joint probability distribution, Pearson correlation coefficient and Spearman's rank correlation coefficients methods in Peninsular Malaysia (PM), Sabah and Sarawak are computed. Joint probability distribution method is considered as a reliable method among three different methods to determine the relationship between load variables. The PM has good correlation between the wind-wave and wave-current; Sabah has both strong relationships of wind-wave and wind-current with 50 year return period; Sarawak has good correlation between wind and current in both 50 years and 100 years return period. Since Sabah has good correlation between the associated load variables, no matter in 50 years or 100 years of return period of load combination. Thus, method 1 of ISO 19901-1, specimen provides guideline for metocean loading conditions, can be adopted for design for offshore structure in Sabah. However, due to weak correlations in PM and Sarawak, this method cannot be applied and method 2, which is current practice in offshore industry, should continueto be used.
ABSTRACT Proper evaluation of load is the most important step for the design of a structure. This... more ABSTRACT Proper evaluation of load is the most important step for the design of a structure. This paper presents the uncertainty modeling of environmental load for jacket platforms in Malaysia. We are interested only in extreme loads for the modeling of environmental load which are distributed by extreme values. Here in this paper, Weibull or Gumbel distributions are used. The existing platforms are designed for 100 year return period but are assessed for 10,000 years as recommended by ISO 19902 and API RP2A. The nature of environmental load is probabilistic and we need to ascertain the randomness of the load. This study covers three parameters of environmental load acting on jacket platforms namely significant wave height (Hs), wind speed and surface current speed in the Peninsular Malaysia (PM) region. Two-parameter Weibull and Gumbel distributions were used for the analysis. The data is in shape of 1, 10, 50, 100 year return period. Parameters of distribution are determined first, which are used to find mean and standard deviation of respective distribution. From this, uncertainty variables are extrapolated up to 1000 and 10,000 years. Finally the data was compared with data from Gulf of Mexico (GOM), Northern North Sea (NNS), Southern North Sea (SNS) and Central North Sea (CNS). This work will lead to determining the reliability of jacket platforms in Malaysia.
Comparison of three offshore jacket platform codes ie API RP2A-WSD (21st edition, 2008) API RP2A-... more Comparison of three offshore jacket platform codes ie API RP2A-WSD (21st edition, 2008) API RP2A-LRFD (1st edition, 2003) and ISO 19902 1st edition, 2007) is made on the foundation strength modelling. A detailed comparison of the provisions of the codes is useful to ...
Worldwide, currently there are three codes used for offshore jacket platform design ie API RP2A W... more Worldwide, currently there are three codes used for offshore jacket platform design ie API RP2A WSD, API RP2A LRFD and ISO 19902. Of these, the ISO code is formulated for application all over the world. API RP2A WSD is still being used for jacket platform design, not only in ...
The construction sector plays a pivotal role in the economy of the nation. The Government and Pri... more The construction sector plays a pivotal role in the economy of the nation. The Government and Private sector invest large amounts of money annually in the construction sector to the tune of say RM 90 Billion. The structural component of building component constitutes a large ...
Working Stress Design is currently used in the design of jacket platforms in Malaysia. Worldwide ... more Working Stress Design is currently used in the design of jacket platforms in Malaysia. Worldwide LRFD codes are being developed. To adopt LRFD code, calibration of resistance factors for joints is necessary in order that new joint designs have the same reliability as the existing ...
Malaysia has been using API RP2A WSD for design of offshore platforms. Many countries have embrac... more Malaysia has been using API RP2A WSD for design of offshore platforms. Many countries have embraced the probability based design through the use of the LRFD method. Due to this and many other factors, it is essential to adopt the LRFD methodology. When adopting this ...
Codes applicable to Jacket platforms such as API WSD, API LRFD and ISO 19902, are based on compon... more Codes applicable to Jacket platforms such as API WSD, API LRFD and ISO 19902, are based on component and joint reliability design.
Journal of the Institution of …, 2011
E3S Web of Conferences
Floods are one of the most damaging natural disasters which occur frequently in the world. They o... more Floods are one of the most damaging natural disasters which occur frequently in the world. They occur every year in Malaysia due to higher precipitation rates, river meandering, and heavily populated suburban areas. Monsoon rains are the major cause of floods and occur two times per year. The heavy floods in the Kelantan River Basin have shown an increasing trend in recent years. Terrain characteristics of the land and meteorological properties of the region are the main natural factors for this disaster. In this study, the Kuala Krai district of the Kelantan River is selected to be reviewed as the case study for flood risk analysis. Geographical Information System (GIS) integrated with Multicriteria Decision Analysis (MCDA) can be used to evaluate the potential flood risk areas. Historically flooded areas can be extracted from the satellite images to determine flood causing factors for the analysis. At the end of the study, a map of flood risk areas can be generated and validated t...
E3S Web of Conferences
Four reinforced concrete rooms are used in this study, with varying floor areas, openings, and fu... more Four reinforced concrete rooms are used in this study, with varying floor areas, openings, and fuel loads. These rooms are office, Classroom, computer, and chemical laboratories of institutional buildings. The time versus Eurocode (EC) parametric fire relationship is determined and compared with ISO 834 and ASTM 119. The performance of the slab is evaluated based on the EC target reliability index of 3.8 for 50 years design period using the First Order Reliability Method (FORM). The probability of failure and structural reliability of each fire compartment at different fire duration is determined. Variables used were concrete compressive strength, a reduction factor of concrete compressive strength, steel yield strength, concrete cover, slab depth, unit width, and area of steel reinforcement provided. The reliability is determined at each 30 minutes fire duration for all fire compartments. The starting point is ambient temperature, then after every thirty minutes until the time when...
Journal of Marine Science and Engineering, 2022
The behavior of different mooring line materials has a significant influence on the behavior of t... more The behavior of different mooring line materials has a significant influence on the behavior of the mooring system and, consequently, the dynamic responses of the floating platform. Although there have been previous studies on FPSOs and their mooring systems, the influence of mooring line failure scenarios associated with different mooring materials has received less attention, particularly for turret-moored FPSOs with taut moorings. Thus, this paper investigates the behavior of different mooring line materials in intact, single-line, and double-line damaged conditions on the hydrodynamic responses of the FPSO, restoring behavior, mooring, and riser tensions considering wave conditions in the Gulf of Mexico. Mooring lines including Aramid, HMPE, polyester, and steel wire were considered in the middle segment, which was the segment of interest in this study. The restoring forces of the mooring system were found to increase with increasing mooring stiffness, and a higher stiffness res...
IEEE Access, 2021
The Jacket platform needs gas and diesel to run its turbines, and in the end, they produce catast... more The Jacket platform needs gas and diesel to run its turbines, and in the end, they produce catastrophic emissions annually. The environmental concerns regarding these platforms have forced us to utilize an alternative source of energy that is sustainable and clean. In this study 51 locations, are of interest where oil and gas activities are in progress at present in the shape of a jacket platform or pipelines. The significant wave height and wave period scatter diagram data are collected from the platforms in the South China Sea. The linear wave theory is used to find the wave power. The given time period is converted into an equivalent time period first before wave energy is determined. The study shows that location no. 20 is the ideal location to deploy the wave energy converter Pelamis P2 with a potential mean wave power of 6.61 kW/m A single unit of Pelamis P2 can produce on an average electricity output of 91.37 kW/m including, the losses and machine efficiencies, whereas a wave farm can generate an average output of 62 GWh/ yr. The electricity supply of 70.3 % of the minimum and 14.1 % of the maximum energy demand, while using only wave energy converter. If hybrid wind and wave energy system is used, then energy production will increase. The results show that the wave farm could also reduce the use of natural gas up to 17.6E06 m 3 / year, avoiding the emission of 12000 tonnes of CO and 54000 tonnes of NOx annually, and can save up to RM 20 billion annually with the reduction of natural gas emissions. INDEX TERMS Wave energy converter, renewable energy, South China Sea, metocean, jacket platform.
A numerical method of predicting the turbulent mixing process of a treated sewer disposed from a ... more A numerical method of predicting the turbulent mixing process of a treated sewer disposed from a marine outfall is described. The momentum equations for the sea water mixed with treated water of small salinity and warmer temperature are solved numerically together with the equation of the concentration of the treated water. The basic method is a Large Eddy Simulation (LES) formulated on a fixed rectangular grid where boundaries are approximated by Immersed Boundary (IB) method. The sub-grid effects of the unresolved fluctuations of velocity and the concentration fields are expressed by the eddy viscosity and eddy diffusivity with the Smagorinsky model. The method is verified with an experiment and RANS calculation of the buoyant wall jet issuing on a solid surface. The method then is used to simulate the dispersion and dilution of the effluent from a typical marine outfall installed on the seabed of shallow coastal water. The behavior of the plume in the vicinity of the outfall is s...
Large eddy simulation of buoyant jet in shallow water Akihiko Nakayama, Jeremy D. Bricker and Zaf... more Large eddy simulation of buoyant jet in shallow water Akihiko Nakayama, Jeremy D. Bricker and Zafarullah Nizamani Department of Environmental Engineering, Universiti Tunku Abdul Rahman akihiko@utar.edu.my Abstract A numerical method of predicting the turbulent mixing process of disposed water from an outfall in a shallow coastal water is described. The momentum equations for the sea water mixed with treated water of small salinity and warmer temperature are solved numerically together with the equation of the concentration of the treated water. The basic method is a Large Eddy Simulation (LES) formulated on a fixed rectangular grid where boundaries are approximated by Immersed Boundary (IB) method. The sub-grid effects of the unresolved fluctuations of velocity and the concentration fields are expressed by the eddy viscosity and eddy diffusivity with the Smagorinsky model. The method is verified with an experiment and RANS calculation of the buoyant wall jet issuing on a solid surfa...
The effects of the surface waves generated by the wind have a significant effect on the currents.... more The effects of the surface waves generated by the wind have a significant effect on the currents. A wave current coupled model plays an important role in the design of offshore structures. The interaction between fluids such as incompressible ocean waves and current and offshore structures is significant with many real-time applications in offshore engineering. These coupled models can be applied to Offshore Floating Production Operating and offloading (FPSO), Wind or current turbines and offshore pipelines. The complex issues related to the design are analyzed by using Computational Fluid Dynamics, which requires an investigation of the multiphase flow between wave and current and the structure which is considered restrictive due to the computational cost. If viscous effects are neglected then the single-phase flow models have been recommended, where wave-current interaction have been modelled successfully. Models have been developed where velocities and pressure are computed and t...
CFD Letters, 2020
The effects of the surface waves generated by the wind have a significant effect on the currents.... more The effects of the surface waves generated by the wind have a significant effect on the currents. A wave current coupled model plays an important role in the design offshore structures. The interaction between fluids such as incompressible ocean waves and current and offshore structures is significant with many real-time applications in offshore engineering. These coupled models can be applied to Offshore Floating Production Operating and offloading (FPSO), Wind or current turbines and offshore pipelines. The complex issues related to the design are analyzed by using Computational Fluid Dynamics, which requires an investigation of the multiphase flow between wave and current and the structure which is considered restrictive due to the computational cost. If viscous effects are neglected then the single-phase flow models have been recommended, where wave-current interaction have been modelled successfully. Models have been developed where velocities and pressure are computed and the results can be verified with the experimental results available in the literature. In this study the existing numerical methods, mesh types are discussed along with their coupling methods. Here single-phase and multiphase models with small and medium movement are reviewed and their applications are highlighted. Commercial CFD code ANSYS Fluent has been found most reliable and easy to use tool for the analysis of fluid flow interacting with offshore structures near the free surface. It can successfully be used for determination of fluid dynamics of offshore environments installed complex multi-component structures. Dynamic mesh facility is more useful for multiphase modelling of floating structures.
MATEC Web of Conferences, 2018
Most of the residential buildings in Malaysia are not designed to withstand the seismic forces, w... more Most of the residential buildings in Malaysia are not designed to withstand the seismic forces, while the high-rise buildings. However, since the Sumatra 2004 earthquake, there had been increasing concerns about the structure vulnerability in our country to earthquakes. Several recent studies had also revealed that Malaysia had the possibility to be influenced by both local and far field earthquakes. This study is conducted to analyze the vulnerability of a high rise building to local and far field earthquakes using Scia Engineer. Modal Response Spectrum method of Scia Engineer is used. The model is a 12 story hotel building from Ipoh, Perak. The designing code is the Eurocode with Malaysia Annex. Different Peak Ground Accelerations (PGA) that represents the local and far field earthquakes is acted on the model to obtain the seismic performance. The deformation of the building by the seismic combinations is compared to the ASCE-7 design to evaluate the vulnerability. Research of sei...
INTERNATIONAL SYMPOSIUM ON GREEN AND SUSTAINABLE TECHNOLOGY (ISGST2019), 2019
The importance is given for the efficient design of offshore structures which should include econ... more The importance is given for the efficient design of offshore structures which should include economic and safety concerns. The properties of wind-generated (main) surface waves and currents are recognized to play a vital role during design of offshore structures such as windmills, fixed and floating structures. This study looks into the mechanisms of metocean forces, acting on these structures near the continental shelf region of Malaysia. At present, near offshore Malaysia, there is no real behaviour model available for currents and the interaction between waves and current. The free surface flow and rigid body interaction with structural issues of offshore structures such as fatigue, corrosion, and marine growth are also not researched in this region before. Therefore, current and wave-current models need to be developed using the finite volume method. Physics of these forces need to be determined and their free surface flow motions require the development of a framework. Fluidstructure interaction (FSI) is used to model the interfaces such as air-fluid (free surface) and fluid-structure (rigid-body). A Freesurface/rigid body problem fully coupled finite volume model is a preferred method. Six degree of freedom of motion equations are used to define the rigid body. This paper is based on literature review and the expected results due to the effects of wind on wave and currents and the mechanics of current are highlighted along with the seasonal effects of the current. To deal with the moving rigid body and the fluid domain interface an interface-tracking method is used.
MATEC Web of Conferences, 2017
Fluid structure interaction (FSI) applications are of wide range from offshore fixed and floating... more Fluid structure interaction (FSI) applications are of wide range from offshore fixed and floating structures to offshore pipelines. Reynolds Averaged Navier Stoke (RANS) solution has limitation for unsteady and turbulent flow modelling. A possible approach is Large Eddy Simulation (LES) and it is applied to flows past a circular cylinder located far above, near and on a flat seabed. The Reynolds number considered is based on the real situation off Malaysia Coast and is sub-critical around 105. Hydrodynamic quantities in terms of mean pressure are predicted and vortex shedding mechanism is evaluated. The results are validated by comparing the simulation and experimental previous studies.
MATEC web of conferences, 2017
Metocean environmental load includes wind, wave and currents. Offshore structures are designed fo... more Metocean environmental load includes wind, wave and currents. Offshore structures are designed for two environmental load design conditions i.e. extreme and operational load conditions of environmental loads are evaluated. The ccorrelation between load variables using Joint probability distribution, Pearson correlation coefficient and Spearman's rank correlation coefficients methods in Peninsular Malaysia (PM), Sabah and Sarawak are computed. Joint probability distribution method is considered as a reliable method among three different methods to determine the relationship between load variables. The PM has good correlation between the wind-wave and wave-current; Sabah has both strong relationships of wind-wave and wind-current with 50 year return period; Sarawak has good correlation between wind and current in both 50 years and 100 years return period. Since Sabah has good correlation between the associated load variables, no matter in 50 years or 100 years of return period of load combination. Thus, method 1 of ISO 19901-1, specimen provides guideline for metocean loading conditions, can be adopted for design for offshore structure in Sabah. However, due to weak correlations in PM and Sarawak, this method cannot be applied and method 2, which is current practice in offshore industry, should continueto be used.
ABSTRACT Proper evaluation of load is the most important step for the design of a structure. This... more ABSTRACT Proper evaluation of load is the most important step for the design of a structure. This paper presents the uncertainty modeling of environmental load for jacket platforms in Malaysia. We are interested only in extreme loads for the modeling of environmental load which are distributed by extreme values. Here in this paper, Weibull or Gumbel distributions are used. The existing platforms are designed for 100 year return period but are assessed for 10,000 years as recommended by ISO 19902 and API RP2A. The nature of environmental load is probabilistic and we need to ascertain the randomness of the load. This study covers three parameters of environmental load acting on jacket platforms namely significant wave height (Hs), wind speed and surface current speed in the Peninsular Malaysia (PM) region. Two-parameter Weibull and Gumbel distributions were used for the analysis. The data is in shape of 1, 10, 50, 100 year return period. Parameters of distribution are determined first, which are used to find mean and standard deviation of respective distribution. From this, uncertainty variables are extrapolated up to 1000 and 10,000 years. Finally the data was compared with data from Gulf of Mexico (GOM), Northern North Sea (NNS), Southern North Sea (SNS) and Central North Sea (CNS). This work will lead to determining the reliability of jacket platforms in Malaysia.
Comparison of three offshore jacket platform codes ie API RP2A-WSD (21st edition, 2008) API RP2A-... more Comparison of three offshore jacket platform codes ie API RP2A-WSD (21st edition, 2008) API RP2A-LRFD (1st edition, 2003) and ISO 19902 1st edition, 2007) is made on the foundation strength modelling. A detailed comparison of the provisions of the codes is useful to ...
Worldwide, currently there are three codes used for offshore jacket platform design ie API RP2A W... more Worldwide, currently there are three codes used for offshore jacket platform design ie API RP2A WSD, API RP2A LRFD and ISO 19902. Of these, the ISO code is formulated for application all over the world. API RP2A WSD is still being used for jacket platform design, not only in ...
The construction sector plays a pivotal role in the economy of the nation. The Government and Pri... more The construction sector plays a pivotal role in the economy of the nation. The Government and Private sector invest large amounts of money annually in the construction sector to the tune of say RM 90 Billion. The structural component of building component constitutes a large ...
Working Stress Design is currently used in the design of jacket platforms in Malaysia. Worldwide ... more Working Stress Design is currently used in the design of jacket platforms in Malaysia. Worldwide LRFD codes are being developed. To adopt LRFD code, calibration of resistance factors for joints is necessary in order that new joint designs have the same reliability as the existing ...
Malaysia has been using API RP2A WSD for design of offshore platforms. Many countries have embrac... more Malaysia has been using API RP2A WSD for design of offshore platforms. Many countries have embraced the probability based design through the use of the LRFD method. Due to this and many other factors, it is essential to adopt the LRFD methodology. When adopting this ...
Codes applicable to Jacket platforms such as API WSD, API LRFD and ISO 19902, are based on compon... more Codes applicable to Jacket platforms such as API WSD, API LRFD and ISO 19902, are based on component and joint reliability design.
Journal of the Institution of …, 2011