Dynamic work environments in construction and civil infrastructure sectors remain susceptible to ... more Dynamic work environments in construction and civil infrastructure sectors remain susceptible to safety risks. Although previous research has resulted in improvements, there is currently a gap in measuring temporal impacts of safety risks quantitatively. Precise modeling of potential delays caused by safety incidents is vital for efficient management of risks and making informed decisions on project contingency. Toward this aim, the current research adopts a nondeterministic modeling method to simulate and quantify safety incidents and find correlations with project delays. Using a deductive approach, three research questions were formulated, and investigations conducted on Australian data collected from 2016 onwards. Quantitative impacts of safety risks on project completion times were numerically measured. Furthermore, safety risks were ranked based on their significance of temporal impacts on project performance. This paper contributes to the theory of safety management by developing a nondeterministic method to model impacts of safety risks at both industry and project levels. Practical contributions and outcomes can facilitate using machine learning methods to plan proportionate time buffers to address safety risks.
There is an ever increasing need to extend the life of aging offshore structures beyond their ori... more There is an ever increasing need to extend the life of aging offshore structures beyond their original design life. Whether these structures are fixed offshore rigs or floating facilities, operators are continually looking for requalification and extension of the service life aimed at ensuring the integrity of the structure. With a continued requirement to produce oil or gas, either from the original fields or as a base for neighbouring subsea completions, many of these respective offshore installations are likely to remain operational for a period of time in the foreseeable future. The ageing offshore infrastructure presents a constant and growing challenge. Ageing is characterised by deterioration, change in operational conditions or accidental damages which, in the severe operational environment offshore, can be significant with serious consequences for installation integrity if not managed adequately and efficiently. In order to ensure technical and operational integrity of thes...
The world has a quarter of its natural gas reserves (approximately 2 billion TCF) undeveloped or ... more The world has a quarter of its natural gas reserves (approximately 2 billion TCF) undeveloped or "Stranded" in offshore fields. Many gas fields were discovered decades ago, but until just recently these reserves were considered to be commercially and technically non-viable. Floating Liquefied Natural Gas, or FLNG, is now seen as a potentially viable solution to monetize these reserves. Technology developments in offshore Liquefied Natural Gas (LNG) liquefaction, containment and transfer have made offshore FLNG production commercially viable. Although land-based LNG and offshore FPSOs are each successfully proven in operations, combining the two technologies into a FLNG is complicated and faces various technical challenges. These include safety, ship motion, topside processing, hull & containment, offloading, integration and operation. One of the critical aspects of a FLNG facility are the space constraints inherent in any floater.. A concrete hull structure can be a good answer to these challenges. It can provide a floater with larger deck area and high built-in load-bearing capacity. Concrete has excellent durability in marine environments, is not subject to fatigue, and offers far better insulation properties than steel. This paper serves to highlight the benefits of a proposed concrete hull structure for FLNG production facility. The proposed concrete monohull concept benefits from significant flexibility with regards to topsides weight, equipment lay-out, simplification of operations and maintenance. Concrete has better fire resistance and corrosive resistance than steel structures and it is not susceptible to brittle fracture in the case of an LNG spill. These are considered to be of major importance for a FLNG production vessel. Building cost and time-scale are competitive.
International Petroleum Technology Conference, 2015
The integrity management, changes, repairs, upgrades and modification of offshore infrastructure ... more The integrity management, changes, repairs, upgrades and modification of offshore infrastructure to meet the functionality and operational availability requirements presents a constant and growing challenge for operators. A bolted connection arrangement can form a constructible and cost effective solution for the modification of existing platforms with minimum impact on platform operations. Historically, bolted connections have been avoided due to concerns about integrity management and degradation mechanism uncertainties and corrosion in particular. However, where structures are not in direct contact with sea spray, and given appropriate safety and integrity procedures, bolted connections can be used successfully on live production platforms to mitigate risks without the exposure to hot work. The use of bolted connections covers a wide range of applications. This implies that the requirements for a bolted connection must be specified in relation to the given application and its cri...
Redeployment of existing idle or close to end of lease mobile production units can provide a viab... more Redeployment of existing idle or close to end of lease mobile production units can provide a viable option to address financial and delivery time challenges for development of marginal field or revitalisation of the end of life for production assets. The deployment of an existing MOPU readily meets these requirements with a potentially faster upgrade, integrity assessment and modification project timetable as opposed to conventional new build Facility. It also typically will have a simpler installation procedure and minimal abandonment costs. There are examples of this type project being delivered from formal project kick off to production in less than a year. The challenges for this type of project are managing the technical aspects of integrity assessment and m odification of topside layout, fast track delivery of either new or refurbished long lead equipment packages and structural integrity and refurbishment of the existing unit to a site specific fixed structure under a specifi...
Investigations into the performance of concrete plugs in tubular steel piles under tension and co... more Investigations into the performance of concrete plugs in tubular steel piles under tension and compression have been conducted at Monash University over the past three years. The work presented in this paper reports the result of push out tests carried out on seven steel tubes specimens filled with reinforced concrete plugs with variable depths. Only one tube diameter, one concrete strength and one reinforcement arrangement was tested. The single variable was the length of the plug. Test results included the ultimate push -out forces, slip of concrete plugs, and longitudinal and hoop strains along the piles for some specimens. Strain measurements on the steel tube allowed the determination of shear transfer during the push out tests. The tests clearly showed that average bond strength achieved in compression significantly exceeds expectations and it is higher than the results of previous investigations using plugs without reinforcement.
This paper compares and reviews the recommendations and contents of the guide for the design and ... more This paper compares and reviews the recommendations and contents of the guide for the design and construction of externally bonded FRP systems for strengthening concrete structures reported by ACI committee 440 and technical report of Externally bonded FRP reinforcement for RC structures (FIB 14) in application of carbon fiber reinforced polymer (CFRP) composites in strengthening of an aging reinforced concrete headstock. The paper also discusses the background, limitations, strengthening for flexure and shear, and other related issues in use of FRP for strengthening of a typical reinforced concrete headstock structure such as durability, de-bonding, strengthening limits, fire and environmental conditions. A case study of strengthening of a bridge headstock using FRP composites is presented as a worked example in order to illustrate and compare the differences between these two design guidelines when used in conjunction with the philosophy of the Austroads (1992) bridge design code.
Performance-based seismic engineering is now an established technology for buildings that can be ... more Performance-based seismic engineering is now an established technology for buildings that can be adopted for offshore platforms. The development of performance-based seismic design criteria and applicability of this method for fixed offshore platforms was discussed in this paper. An analytical example including the inelastic time history analysis was presented. Structural performance and performance based assessment results was then compared with API and ISO recommendations. The results demonstrated that the performance based assessment is more reliable and may improve the integrity of the design to resist earthquakes. The results also indicated a better match between ISO standard and performance based design for the example platform.
During the life-cycle of an offshore structure the ultimate capacity is an important attribute th... more During the life-cycle of an offshore structure the ultimate capacity is an important attribute that affects the life expectancy, requalification and life extension of the facility, and can significantly influence the reliability levels and operational costs. This paper provides an overview of ultimate strength assessments and their role in understanding the structural system response and failure modes to extreme loads for requalification and life extension and demonstrating fitness forpurpose of thirteen identified platforms. This paper also discusses the failure modes in ultimate strength of structures taking account of the nonlinear behavior of members, joints and piling foundation.
Dynamic work environments in construction and civil infrastructure sectors remain susceptible to ... more Dynamic work environments in construction and civil infrastructure sectors remain susceptible to safety risks. Although previous research has resulted in improvements, there is currently a gap in measuring temporal impacts of safety risks quantitatively. Precise modeling of potential delays caused by safety incidents is vital for efficient management of risks and making informed decisions on project contingency. Toward this aim, the current research adopts a nondeterministic modeling method to simulate and quantify safety incidents and find correlations with project delays. Using a deductive approach, three research questions were formulated, and investigations conducted on Australian data collected from 2016 onwards. Quantitative impacts of safety risks on project completion times were numerically measured. Furthermore, safety risks were ranked based on their significance of temporal impacts on project performance. This paper contributes to the theory of safety management by developing a nondeterministic method to model impacts of safety risks at both industry and project levels. Practical contributions and outcomes can facilitate using machine learning methods to plan proportionate time buffers to address safety risks.
There is an ever increasing need to extend the life of aging offshore structures beyond their ori... more There is an ever increasing need to extend the life of aging offshore structures beyond their original design life. Whether these structures are fixed offshore rigs or floating facilities, operators are continually looking for requalification and extension of the service life aimed at ensuring the integrity of the structure. With a continued requirement to produce oil or gas, either from the original fields or as a base for neighbouring subsea completions, many of these respective offshore installations are likely to remain operational for a period of time in the foreseeable future. The ageing offshore infrastructure presents a constant and growing challenge. Ageing is characterised by deterioration, change in operational conditions or accidental damages which, in the severe operational environment offshore, can be significant with serious consequences for installation integrity if not managed adequately and efficiently. In order to ensure technical and operational integrity of thes...
The world has a quarter of its natural gas reserves (approximately 2 billion TCF) undeveloped or ... more The world has a quarter of its natural gas reserves (approximately 2 billion TCF) undeveloped or "Stranded" in offshore fields. Many gas fields were discovered decades ago, but until just recently these reserves were considered to be commercially and technically non-viable. Floating Liquefied Natural Gas, or FLNG, is now seen as a potentially viable solution to monetize these reserves. Technology developments in offshore Liquefied Natural Gas (LNG) liquefaction, containment and transfer have made offshore FLNG production commercially viable. Although land-based LNG and offshore FPSOs are each successfully proven in operations, combining the two technologies into a FLNG is complicated and faces various technical challenges. These include safety, ship motion, topside processing, hull & containment, offloading, integration and operation. One of the critical aspects of a FLNG facility are the space constraints inherent in any floater.. A concrete hull structure can be a good answer to these challenges. It can provide a floater with larger deck area and high built-in load-bearing capacity. Concrete has excellent durability in marine environments, is not subject to fatigue, and offers far better insulation properties than steel. This paper serves to highlight the benefits of a proposed concrete hull structure for FLNG production facility. The proposed concrete monohull concept benefits from significant flexibility with regards to topsides weight, equipment lay-out, simplification of operations and maintenance. Concrete has better fire resistance and corrosive resistance than steel structures and it is not susceptible to brittle fracture in the case of an LNG spill. These are considered to be of major importance for a FLNG production vessel. Building cost and time-scale are competitive.
International Petroleum Technology Conference, 2015
The integrity management, changes, repairs, upgrades and modification of offshore infrastructure ... more The integrity management, changes, repairs, upgrades and modification of offshore infrastructure to meet the functionality and operational availability requirements presents a constant and growing challenge for operators. A bolted connection arrangement can form a constructible and cost effective solution for the modification of existing platforms with minimum impact on platform operations. Historically, bolted connections have been avoided due to concerns about integrity management and degradation mechanism uncertainties and corrosion in particular. However, where structures are not in direct contact with sea spray, and given appropriate safety and integrity procedures, bolted connections can be used successfully on live production platforms to mitigate risks without the exposure to hot work. The use of bolted connections covers a wide range of applications. This implies that the requirements for a bolted connection must be specified in relation to the given application and its cri...
Redeployment of existing idle or close to end of lease mobile production units can provide a viab... more Redeployment of existing idle or close to end of lease mobile production units can provide a viable option to address financial and delivery time challenges for development of marginal field or revitalisation of the end of life for production assets. The deployment of an existing MOPU readily meets these requirements with a potentially faster upgrade, integrity assessment and modification project timetable as opposed to conventional new build Facility. It also typically will have a simpler installation procedure and minimal abandonment costs. There are examples of this type project being delivered from formal project kick off to production in less than a year. The challenges for this type of project are managing the technical aspects of integrity assessment and m odification of topside layout, fast track delivery of either new or refurbished long lead equipment packages and structural integrity and refurbishment of the existing unit to a site specific fixed structure under a specifi...
Investigations into the performance of concrete plugs in tubular steel piles under tension and co... more Investigations into the performance of concrete plugs in tubular steel piles under tension and compression have been conducted at Monash University over the past three years. The work presented in this paper reports the result of push out tests carried out on seven steel tubes specimens filled with reinforced concrete plugs with variable depths. Only one tube diameter, one concrete strength and one reinforcement arrangement was tested. The single variable was the length of the plug. Test results included the ultimate push -out forces, slip of concrete plugs, and longitudinal and hoop strains along the piles for some specimens. Strain measurements on the steel tube allowed the determination of shear transfer during the push out tests. The tests clearly showed that average bond strength achieved in compression significantly exceeds expectations and it is higher than the results of previous investigations using plugs without reinforcement.
This paper compares and reviews the recommendations and contents of the guide for the design and ... more This paper compares and reviews the recommendations and contents of the guide for the design and construction of externally bonded FRP systems for strengthening concrete structures reported by ACI committee 440 and technical report of Externally bonded FRP reinforcement for RC structures (FIB 14) in application of carbon fiber reinforced polymer (CFRP) composites in strengthening of an aging reinforced concrete headstock. The paper also discusses the background, limitations, strengthening for flexure and shear, and other related issues in use of FRP for strengthening of a typical reinforced concrete headstock structure such as durability, de-bonding, strengthening limits, fire and environmental conditions. A case study of strengthening of a bridge headstock using FRP composites is presented as a worked example in order to illustrate and compare the differences between these two design guidelines when used in conjunction with the philosophy of the Austroads (1992) bridge design code.
Performance-based seismic engineering is now an established technology for buildings that can be ... more Performance-based seismic engineering is now an established technology for buildings that can be adopted for offshore platforms. The development of performance-based seismic design criteria and applicability of this method for fixed offshore platforms was discussed in this paper. An analytical example including the inelastic time history analysis was presented. Structural performance and performance based assessment results was then compared with API and ISO recommendations. The results demonstrated that the performance based assessment is more reliable and may improve the integrity of the design to resist earthquakes. The results also indicated a better match between ISO standard and performance based design for the example platform.
During the life-cycle of an offshore structure the ultimate capacity is an important attribute th... more During the life-cycle of an offshore structure the ultimate capacity is an important attribute that affects the life expectancy, requalification and life extension of the facility, and can significantly influence the reliability levels and operational costs. This paper provides an overview of ultimate strength assessments and their role in understanding the structural system response and failure modes to extreme loads for requalification and life extension and demonstrating fitness forpurpose of thirteen identified platforms. This paper also discusses the failure modes in ultimate strength of structures taking account of the nonlinear behavior of members, joints and piling foundation.
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Papers by Abe Nezamian