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Papers by Maurice Ephraim

Day 2 Tue, August 03, 2021, 2021

Offshore oil and gas pipelines are subjected to high pressure and high temperature (HP/HT) from t... more Offshore oil and gas pipelines are subjected to high pressure and high temperature (HP/HT) from the inner hydrocarbon content during operation. Both the rise in temperature and internal pressure may cause longitudinal expansion of the pipeline. This expansion is restrained or semi-restrained by the pipe end devices and the soil which results in build-up of compression stresses in the pipe wall. These pipelines are also exposed to so many familiar and unfamiliar forces related to static, dynamic and environmental forces. This study presents a thorough review of various sources from literature on the integrity challenges of subsea flowlines and pipelines amid challenging operating conditions especially with regards to flow assurance. This paper evaluates the impact of hydrate deposition and agitation on the overall integrity of the subsea flowlines, riser-base and fitting e.g. elbows, valves e.t.c. A bow tie model was developed to determine the threats, causes, consequences, the top e...

American Journal of Civil Engineering, 2018

The convergence of numerical solution based on two nodded beam finite element require considerabl... more The convergence of numerical solution based on two nodded beam finite element require considerable number of iterations and time; and is also plagued with shear locking. To address these deficiencies a three nodded beam element is proposed in this study to simulate the behavior of beams on elastic foundation. The analytical formulation of the model and development of shape functions are achieved with assumption of Winkler hypothesis for beam on elastic foundation A Matlab programme was developed to determine the combined beam and foundation stiffness as well as the load vector. The proposed model reliably simulates the deformations and stress resultants of beam on elastic foundation under general loading conditions. The result showed faster convergence devoid of shear locking. The maximum deflection and bending moment differ from the classical solution by about 5 percent.

This work is licensed under a Creative Commons Attribution 4.0 International License. ___________... more This work is licensed under a Creative Commons Attribution 4.0 International License. _______________________________________________________________ ABSTRACT. Soil reinforcement is used to improve most of the soil mechanical properties. Oil palm fruit fibre is one of the widely used natural fibres for soil reinforcement. This study presents the effect of oil palm fruit fibres on the behaviour of a lateritic soil. Results show that the characteristics of the reinforced soil may not necessarily be improved by the randomly distributed reinforcement, but would significantly affect and alter the characteristics of the soil. Copyright © IJEATR, all rights reserved.

This work is related to study the compressive strength of concrete using quarry dust as fine aggr... more This work is related to study the compressive strength of concrete using quarry dust as fine aggregate instead of sand and 10mm washed aggregate instead of conventional granite. Three mixes of 1:2½:3, 1:1½:2 and 1:1:2 (by weight) and at water-cement ratios (w/c) of 0.65, 0.60 and 0.45 for grade 20, 30 and 40 respectively were designed. However, these mixes gave characteristic strengths of 18.88N/mm 2 28.23N/mm 2 and 38.29N/mm 2 respectively equivalent to grade 15, 25, and 35 respectively. Though the aggregate/cement ratio of concrete is lower than that of conventional granite concrete, workability value compared favourably with the conventional granite concrete.Therefore the 10mm washed aggregate and quarry dust satisfied the requirements of code provision in properties studies and can serve as full replacement for conventional granite and natural river sand respectively.

International Journal for Computational Civil and Structural Engineering

Rigid frames subjected to critical loads are assumed to fail when the columns fail. The attached ... more Rigid frames subjected to critical loads are assumed to fail when the columns fail. The attached beams act as partial elastic restraints to the columns while the base supports are assumed to be pinned or fixed. This study presents the results of extensive laboratory investigation of the critical load of steel frames models of various stiffness values (K = 0.5, 0.75, 1.0, 1.25 and 1.5) with fixed and pinned supports respectively. The critical load values and lateral deflection obtained from experiments are plotted against the beam column stiffness ratios kb/kc. Based on the test results, a linear relationship between the critical load and the selected stiffness ratios of the frame models was established within the elastic range. The results were used to validate the works of some recently proposed approximate formulae and empirical model for stability of frame. These results deviate from the selected approximate method approach by approximately ± 10%.

This research focuses on developing an enhanced rational mix design method for selfcompacting con... more This research focuses on developing an enhanced rational mix design method for selfcompacting concrete and optimizing it with existing specification and modifications of self-compacting concrete generally accepted in the construction industry. Trial mix were prepared and laboratory tests for self-compacting concrete which include slump flow test, J-ring test, V-funnel test and L-Box test were carried out on the fresh concrete. The tests on the trial mix were carried out in accordance with the EFNARC Specification and Guidelines for self-compacting concrete. Compressive strength test, flexural test and split tensile test to BS 1881: 1997 were carried out on a total of 250 cubes, 60 beams and 60 cylinders to investigate the properties of the hardened self-compacting concrete. The proposed new absolute volume method produced a self-compacting concrete with the highest compressive strength of 65 N/mm 2 at 28 days with the same water/cement ratio and best workability in comparison to oth...

The performance of two oil production platforms was investigated with the aim of establishing acc... more The performance of two oil production platforms was investigated with the aim of establishing acceptance criteria for structural performance of offshore platforms located in the benign-sea environment of offshore Nigeria. The platforms were modeled using the Bentley SACS software program with the material characteristics and condition data of two existing 4-legged and 8-legged platforms, located at depths of 8 m and 24 m respectively. In-place linear and pushover non-linear structural analyses were performed on the models and the results, combined with those from structural reliability analysis, formed the basis for the formulation of the acceptance criteria for structural performance. To capture the planes of least resistance, the platforms were subjected to 8-directional environmental loading which yielded the true reserve strength ratio of 1.8 and 1.5 against the values of 2.6 and 1.8, calculated from the traditional broadside load application practice. Furthermore, the results o...

The convergence of numerical solution based on two nodded beam finite element require considerabl... more The convergence of numerical solution based on two nodded beam finite element require considerable number of iterations and time; and is also plagued with shear locking. To address these deficiencies a three nodded beam element is proposed in this study to simulate the behavior of beams on elastic foundation. The analytical formulation of the model and development of shape functions are achieved with assumption of Winkler hypothesis for beam on elastic foundation A Matlab programme was developed to determine the combined beam and foundation stiffness as well as the load vector. The proposed model reliably simulates the deformations and stress resultants of beam on elastic foundation under general loading conditions. The result showed faster convergence devoid of shear locking. The maximum deflection and bending moment differ from the classical solution by about 5 percent.

International Journal for Computational Civil and Structural Engineering

An analytical model based on the experimental trend of the creep deformation of concrete in direc... more An analytical model based on the experimental trend of the creep deformation of concrete in direct tension is developed. The model is calibrated for normal and high strength concretes and the results show good agreement within 10% of experimental data. The inclussion of the stress level is a unique feature of the model and present a prospect of predicting concrete deformation for any regime of loading.The model presents a means for incorporating the nonlinearlity of creep into other predictive models of concrete.

Journal of Engineering Science and Technology

Day 2 Tue, August 03, 2021, 2021

Offshore oil and gas pipelines are subjected to high pressure and high temperature (HP/HT) from t... more Offshore oil and gas pipelines are subjected to high pressure and high temperature (HP/HT) from the inner hydrocarbon content during operation. Both the rise in temperature and internal pressure may cause longitudinal expansion of the pipeline. This expansion is restrained or semi-restrained by the pipe end devices and the soil which results in build-up of compression stresses in the pipe wall. These pipelines are also exposed to so many familiar and unfamiliar forces related to static, dynamic and environmental forces. This study presents a thorough review of various sources from literature on the integrity challenges of subsea flowlines and pipelines amid challenging operating conditions especially with regards to flow assurance. This paper evaluates the impact of hydrate deposition and agitation on the overall integrity of the subsea flowlines, riser-base and fitting e.g. elbows, valves e.t.c. A bow tie model was developed to determine the threats, causes, consequences, the top e...

American Journal of Civil Engineering, 2018

The convergence of numerical solution based on two nodded beam finite element require considerabl... more The convergence of numerical solution based on two nodded beam finite element require considerable number of iterations and time; and is also plagued with shear locking. To address these deficiencies a three nodded beam element is proposed in this study to simulate the behavior of beams on elastic foundation. The analytical formulation of the model and development of shape functions are achieved with assumption of Winkler hypothesis for beam on elastic foundation A Matlab programme was developed to determine the combined beam and foundation stiffness as well as the load vector. The proposed model reliably simulates the deformations and stress resultants of beam on elastic foundation under general loading conditions. The result showed faster convergence devoid of shear locking. The maximum deflection and bending moment differ from the classical solution by about 5 percent.

This work is licensed under a Creative Commons Attribution 4.0 International License. ___________... more This work is licensed under a Creative Commons Attribution 4.0 International License. _______________________________________________________________ ABSTRACT. Soil reinforcement is used to improve most of the soil mechanical properties. Oil palm fruit fibre is one of the widely used natural fibres for soil reinforcement. This study presents the effect of oil palm fruit fibres on the behaviour of a lateritic soil. Results show that the characteristics of the reinforced soil may not necessarily be improved by the randomly distributed reinforcement, but would significantly affect and alter the characteristics of the soil. Copyright © IJEATR, all rights reserved.

This work is related to study the compressive strength of concrete using quarry dust as fine aggr... more This work is related to study the compressive strength of concrete using quarry dust as fine aggregate instead of sand and 10mm washed aggregate instead of conventional granite. Three mixes of 1:2½:3, 1:1½:2 and 1:1:2 (by weight) and at water-cement ratios (w/c) of 0.65, 0.60 and 0.45 for grade 20, 30 and 40 respectively were designed. However, these mixes gave characteristic strengths of 18.88N/mm 2 28.23N/mm 2 and 38.29N/mm 2 respectively equivalent to grade 15, 25, and 35 respectively. Though the aggregate/cement ratio of concrete is lower than that of conventional granite concrete, workability value compared favourably with the conventional granite concrete.Therefore the 10mm washed aggregate and quarry dust satisfied the requirements of code provision in properties studies and can serve as full replacement for conventional granite and natural river sand respectively.

International Journal for Computational Civil and Structural Engineering

Rigid frames subjected to critical loads are assumed to fail when the columns fail. The attached ... more Rigid frames subjected to critical loads are assumed to fail when the columns fail. The attached beams act as partial elastic restraints to the columns while the base supports are assumed to be pinned or fixed. This study presents the results of extensive laboratory investigation of the critical load of steel frames models of various stiffness values (K = 0.5, 0.75, 1.0, 1.25 and 1.5) with fixed and pinned supports respectively. The critical load values and lateral deflection obtained from experiments are plotted against the beam column stiffness ratios kb/kc. Based on the test results, a linear relationship between the critical load and the selected stiffness ratios of the frame models was established within the elastic range. The results were used to validate the works of some recently proposed approximate formulae and empirical model for stability of frame. These results deviate from the selected approximate method approach by approximately ± 10%.

This research focuses on developing an enhanced rational mix design method for selfcompacting con... more This research focuses on developing an enhanced rational mix design method for selfcompacting concrete and optimizing it with existing specification and modifications of self-compacting concrete generally accepted in the construction industry. Trial mix were prepared and laboratory tests for self-compacting concrete which include slump flow test, J-ring test, V-funnel test and L-Box test were carried out on the fresh concrete. The tests on the trial mix were carried out in accordance with the EFNARC Specification and Guidelines for self-compacting concrete. Compressive strength test, flexural test and split tensile test to BS 1881: 1997 were carried out on a total of 250 cubes, 60 beams and 60 cylinders to investigate the properties of the hardened self-compacting concrete. The proposed new absolute volume method produced a self-compacting concrete with the highest compressive strength of 65 N/mm 2 at 28 days with the same water/cement ratio and best workability in comparison to oth...

The performance of two oil production platforms was investigated with the aim of establishing acc... more The performance of two oil production platforms was investigated with the aim of establishing acceptance criteria for structural performance of offshore platforms located in the benign-sea environment of offshore Nigeria. The platforms were modeled using the Bentley SACS software program with the material characteristics and condition data of two existing 4-legged and 8-legged platforms, located at depths of 8 m and 24 m respectively. In-place linear and pushover non-linear structural analyses were performed on the models and the results, combined with those from structural reliability analysis, formed the basis for the formulation of the acceptance criteria for structural performance. To capture the planes of least resistance, the platforms were subjected to 8-directional environmental loading which yielded the true reserve strength ratio of 1.8 and 1.5 against the values of 2.6 and 1.8, calculated from the traditional broadside load application practice. Furthermore, the results o...

The convergence of numerical solution based on two nodded beam finite element require considerabl... more The convergence of numerical solution based on two nodded beam finite element require considerable number of iterations and time; and is also plagued with shear locking. To address these deficiencies a three nodded beam element is proposed in this study to simulate the behavior of beams on elastic foundation. The analytical formulation of the model and development of shape functions are achieved with assumption of Winkler hypothesis for beam on elastic foundation A Matlab programme was developed to determine the combined beam and foundation stiffness as well as the load vector. The proposed model reliably simulates the deformations and stress resultants of beam on elastic foundation under general loading conditions. The result showed faster convergence devoid of shear locking. The maximum deflection and bending moment differ from the classical solution by about 5 percent.

International Journal for Computational Civil and Structural Engineering

An analytical model based on the experimental trend of the creep deformation of concrete in direc... more An analytical model based on the experimental trend of the creep deformation of concrete in direct tension is developed. The model is calibrated for normal and high strength concretes and the results show good agreement within 10% of experimental data. The inclussion of the stress level is a unique feature of the model and present a prospect of predicting concrete deformation for any regime of loading.The model presents a means for incorporating the nonlinearlity of creep into other predictive models of concrete.

Journal of Engineering Science and Technology