M. Almohammad-albakkar - Academia.edu (original) (raw)

Papers by M. Almohammad-albakkar

Journal of constructional steel research, May 1, 2024

Australian Journal of Civil Engineering, 2024

Engineered cementitious composite (ECC) is a highly ductile high-performance fibre-reinforced cem... more Engineered cementitious composite (ECC) is a highly ductile high-performance fibre-reinforced cementitious composite whose design, mixing ratios and other important parameters can be optimised using the theory of micromechanics. This study investigated the effects of different quantities of silica fume and zeolite on the mechanical properties and durability of ECC specimens containing lime stone powder and blast furnace slag when treated in the 5% magnesium sulphate solution at 28, 150, 180 and 210 days of age. The results obtained showed that the compression strengths in lab environment were enhanced up to 25% at the age of 150 days by increasing the silica fume content of the ECC, whereas the modulus of rupture (MOR) and mid-span deflection (MSD) were decreased in all the specimens tested. Meanwhile, a 17% increment in blast furnace slag content was observed to enhance both MSD and MOR at all ages, e.g. it causes 23% increase in MSD and 9% increase in MOR at the age of 28 days. In addition, a 46% increase in lime stone powder content was found to increase compressive strength but to reduce MOR by 7% and 8% at the age of 28 days, respectively.

13th International Congress on Civil Engineering, 2023

In this study, for protecting structures from earthquakes, an innovative type gusset plate damper... more In this study, for protecting structures from earthquakes, an innovative type gusset plate damper was proposed. The new damper consists of strips which are made by creating openings in the gusset plate near to diagonal braces on both sides of them. The proposed damper can be installed in cross-braced frames as ductile fuse and energy dissipater, since this type of lateral-load resisting systems has a low ductility in comparison to moment frames and eccentrically braced frames which is considered as one of the disadvantages of this system. To achieve the research goal, a numerical study was done by using ABAQUS finite element software where the new system was tested under cyclic loading. Based on the numerical results obtained, it was found that the new damper can provide a high ductility with desired stiffness and strength of cross-braced frames. Moreover, this system shows a high energy dissipation capacity, stable hysteretic behavior and similar behavior in tension and compression.

Social Science Research Network, 2022

Considering the importance of analyzing concrete structures under static, cyclic and dynamic load... more Considering the importance of analyzing concrete structures under static, cyclic and dynamic loading, as well as the disability to perform tests on any structure with arbitrary boundary conditions in the laboratory, numerical modeling is used to understand the behavior and analysis of different concrete structures. Therefore, it is necessary to know the stress-strain curve of concrete to perform numerical analysis under cyclic and dynamic loading. So in light of this, in this paper, the behavioral models of concrete under cyclic loading are investigated. For this purpose, a number of concrete behavioral models under static and cyclic loading are reviewed and the mathematical relationships related to some model are presented.

Social Science Research Network, 2022

In this paper, the performance of structures is investigated using linear and nonlinear viscous d... more In this paper, the performance of structures is investigated using linear and nonlinear viscous damper. for this purpose, using ABAQUS finite element software, a 3D model of 3, 5 and 8-story structures is considered under various earthquake records and the results obtained with and without viscous dampers are compared. In this study, the material nonlinearity is considered and for analysis, geometric nonlinearity is applied. The results of numerical analyses showed an improvement in the performance of structural responses under various earthquakes. In addition, the results obtained mentioned that using nonlinear viscous dampers further reduces the seismic responses of the structures as compared to linear viscous dampers.

Considering the importance of analyzing concrete structures under static, cyclic and dynamic load... more Considering the importance of analyzing concrete structures under static, cyclic and dynamic loading, as well as the disability to perform tests on any structure with arbitrary boundary conditions in the laboratory, numerical modeling is used to understand the behavior and analysis of different concrete structures. Therefore, it is necessary to know the stress-strain curve of concrete to perform numerical analysis under cyclic and dynamic loading. So in light of this, in this paper, the behavioral models of concrete under cyclic loading are investigated. For this purpose, a number of concrete behavioral models under static and cyclic loading are reviewed and the mathematical relationships related to some model are presented.

In this paper, the performance of structures is investigated using linear and nonlinear viscous d... more In this paper, the performance of structures is investigated using linear and nonlinear viscous damper. for this purpose, using ABAQUS finite element software, a 3D model of 3, 5 and 8-story structures is considered under various earthquake records and the results obtained with and without viscous dampers are compared. In this study, the material nonlinearity is considered and for analysis, geometric nonlinearity is applied. The results of numerical analyses showed an improvement in the performance of structural responses under various earthquakes. In addition, the results obtained mentioned that using nonlinear viscous dampers further reduces the seismic responses of the structures as compared to linear viscous dampers.

International Journal of Engineering (IJE) , 2023

Seismic excitation can cause significant energy to be released within structures. By using specia... more Seismic excitation can cause significant energy to be released within structures. By using special devices, this energy can be consumed and dissipated without deforming structural members significantly. Due to this, structural damage is minimized, casualties are prevented during earthquakes, and structures are extended in their useful life. Over the past five decades, it has been widely acknowledged that steel yielding dampers are among the best energy dissipation devices. It has been stated that the hysteretic behavior of steel yielding dampers could vary slightly depending on their geometry. From a practical point of view, they are suitable for the improvement of seismic safety in new and existing structures. The purpose of this paper is to present a review related to steel yielding dampers, their development, various types, and applications, in order to help understand the role of these dampers in improving the seismic performance of structures. In terms of their shape, steel yielding dampers can be categorized as steel plate dampers, pipe dampers, curved dampers, and slit dampers. The most common use of steel plate, such as ADAS and TADAS, and pipe dampers is within braced frames, whereas U-shaped, J-shaped, and S-shaped dampers are mostly seen in frames with chevron bracing. Steel curved dampers with a 60° angle in a steel-braced frame, on the other hand, provide the best energy dissipation and frame strength. In this direction, until today, steel slit dampers have been found to be the most commonly used steel yielding dampers.

Research on Engineering Structures and Materials, 2023

Over the past two decades the effects of different admixtures have been investigated on mechanica... more Over the past two decades the effects of different admixtures have been investigated on mechanical properties and durability of engineered cementitious composites (ECC). Despite this, materials such as silica fume and zeolite have not been thoroughly investigated. The present study was designed and implemented to evaluate the effects of silica fume, zeolite, and blast furnace slag (BFS) on engineered cementitious composites and to compare the mechanical properties and durability of the polyvinyl alcohol-ECC (PVA-ECC) and polypropylene-ECC (PP-ECC) specimens. For this purpose, specimens were subjected to adverse conditions in a 5% magnesium sulfate solution and lab conditions as the reference treatment to measure the post-treatment variations in their compressive strength, flexural strength, and mid-span deflection (MSD). Results demonstrated that PP-ECC was not only easier to manufacture but outperformed PVA-ECC in some respects as well. It was also observed that MSD increased in the PVA-ECC specimens but declined in the PP-ECC ones under identical increments in their BFS contents. Finally, all the specimens maintained under the lab conditions displayed the best performance in terms of strength and durability when 3% silica fume was added to their mixtures while the same addition led to the worst performance in the sulfate medium.

Innovative Infrastructure Solutions

Journal of Constructional Steel Research

Australian Journal of Structural Engineering

Journal of Sustainable Cement-Based Materials, 2020

In this paper, the effects of the combined usage of micro-silica (MSi) and/or nanosilica (NSi) on... more In this paper, the effects of the combined usage of micro-silica (MSi) and/or nanosilica (NSi) on the drying shrinkage and compressive strength of the self-compacting concrete (SCC) were investigated. For this purpose, twenty-four types of the SCC mixes made with w/b ratios of 0.35, 0.40, and 0.45 and different percentages of MSi and/or NSi were applied in this research. The replacement ratios included 10% of MSi, 1, 2 or 3% of NSi, 9% MSi þ 1% NSi, 8% MSi þ 2% NSi, and 7% MSi þ 3% NSi. The obtained results revealed that the combined use of 9% MSi þ 1% NSi reduced the 150-day drying shrinkage of the SCC up to 17%, while it increased the 90-day compressive strength of it by 38%, as compared to the control sample. Moreover, it was found that replacing cement by MSi and NSi led to certain synergistic effects and their combination was stronger than the sums of the individual uses.

Asian Journal of Civil Engineering, 2020

This paper presents the combined effects of micro-SiO 2 (MSi) and nano-SiO 2 (NSi) on the water p... more This paper presents the combined effects of micro-SiO 2 (MSi) and nano-SiO 2 (NSi) on the water permeability and absorption of the self-consolidating concrete (SCC). To this aim, eight mixes of the SCC were created with w/b ratio of 0.45 and various proportions of NSi and/or MSi as following; 10% MSi, 1, 2 or 3% NSi, 9% MSi + 1% NSi, 8% MSi + 2% NSi, and 7% MSi + 3% NSi. Consequently, the experimental study showed that the combination of MSi and NSi had a good effect on the water penetration resistance of the SCC. The combination of 9% MSi + 1% NSi lowered the water penetration depth of the SCC nearly 58% and the short-term and total water absorption by approximately 23% and 30%, respectively. The combined addition of MSi and NSi could be more effective; as a result, the microstructure of the SCC would be more uniform and compact, thereby enhancing the water resistance.

Conference Presentations by M. Almohammad-albakkar

The existing design formulas have provided significantly convenient tools to practical engineers ... more The existing design formulas have provided significantly convenient tools to practical engineers in determining the damping coefficients of the supplemental diagonal brace, K brace, upper toggle brace, and lower toggle brace. These formulas take into account the relative vertical and horizontal deformation between the two ends of a viscous damper installed in a frame panel so that the axial deformation of the damper and thus the dissipated energy by the damper can be better captured. In this paper, a mathematical formula is proposed for the internal and external Scissor-Jack brace damper system in structure with the relative vertical and horizontal deformation between the two ends of a viscous damper.

Journal of constructional steel research, May 1, 2024

Australian Journal of Civil Engineering, 2024

Engineered cementitious composite (ECC) is a highly ductile high-performance fibre-reinforced cem... more Engineered cementitious composite (ECC) is a highly ductile high-performance fibre-reinforced cementitious composite whose design, mixing ratios and other important parameters can be optimised using the theory of micromechanics. This study investigated the effects of different quantities of silica fume and zeolite on the mechanical properties and durability of ECC specimens containing lime stone powder and blast furnace slag when treated in the 5% magnesium sulphate solution at 28, 150, 180 and 210 days of age. The results obtained showed that the compression strengths in lab environment were enhanced up to 25% at the age of 150 days by increasing the silica fume content of the ECC, whereas the modulus of rupture (MOR) and mid-span deflection (MSD) were decreased in all the specimens tested. Meanwhile, a 17% increment in blast furnace slag content was observed to enhance both MSD and MOR at all ages, e.g. it causes 23% increase in MSD and 9% increase in MOR at the age of 28 days. In addition, a 46% increase in lime stone powder content was found to increase compressive strength but to reduce MOR by 7% and 8% at the age of 28 days, respectively.

13th International Congress on Civil Engineering, 2023

In this study, for protecting structures from earthquakes, an innovative type gusset plate damper... more In this study, for protecting structures from earthquakes, an innovative type gusset plate damper was proposed. The new damper consists of strips which are made by creating openings in the gusset plate near to diagonal braces on both sides of them. The proposed damper can be installed in cross-braced frames as ductile fuse and energy dissipater, since this type of lateral-load resisting systems has a low ductility in comparison to moment frames and eccentrically braced frames which is considered as one of the disadvantages of this system. To achieve the research goal, a numerical study was done by using ABAQUS finite element software where the new system was tested under cyclic loading. Based on the numerical results obtained, it was found that the new damper can provide a high ductility with desired stiffness and strength of cross-braced frames. Moreover, this system shows a high energy dissipation capacity, stable hysteretic behavior and similar behavior in tension and compression.

Social Science Research Network, 2022

Considering the importance of analyzing concrete structures under static, cyclic and dynamic load... more Considering the importance of analyzing concrete structures under static, cyclic and dynamic loading, as well as the disability to perform tests on any structure with arbitrary boundary conditions in the laboratory, numerical modeling is used to understand the behavior and analysis of different concrete structures. Therefore, it is necessary to know the stress-strain curve of concrete to perform numerical analysis under cyclic and dynamic loading. So in light of this, in this paper, the behavioral models of concrete under cyclic loading are investigated. For this purpose, a number of concrete behavioral models under static and cyclic loading are reviewed and the mathematical relationships related to some model are presented.

Social Science Research Network, 2022

In this paper, the performance of structures is investigated using linear and nonlinear viscous d... more In this paper, the performance of structures is investigated using linear and nonlinear viscous damper. for this purpose, using ABAQUS finite element software, a 3D model of 3, 5 and 8-story structures is considered under various earthquake records and the results obtained with and without viscous dampers are compared. In this study, the material nonlinearity is considered and for analysis, geometric nonlinearity is applied. The results of numerical analyses showed an improvement in the performance of structural responses under various earthquakes. In addition, the results obtained mentioned that using nonlinear viscous dampers further reduces the seismic responses of the structures as compared to linear viscous dampers.

Considering the importance of analyzing concrete structures under static, cyclic and dynamic load... more Considering the importance of analyzing concrete structures under static, cyclic and dynamic loading, as well as the disability to perform tests on any structure with arbitrary boundary conditions in the laboratory, numerical modeling is used to understand the behavior and analysis of different concrete structures. Therefore, it is necessary to know the stress-strain curve of concrete to perform numerical analysis under cyclic and dynamic loading. So in light of this, in this paper, the behavioral models of concrete under cyclic loading are investigated. For this purpose, a number of concrete behavioral models under static and cyclic loading are reviewed and the mathematical relationships related to some model are presented.

In this paper, the performance of structures is investigated using linear and nonlinear viscous d... more In this paper, the performance of structures is investigated using linear and nonlinear viscous damper. for this purpose, using ABAQUS finite element software, a 3D model of 3, 5 and 8-story structures is considered under various earthquake records and the results obtained with and without viscous dampers are compared. In this study, the material nonlinearity is considered and for analysis, geometric nonlinearity is applied. The results of numerical analyses showed an improvement in the performance of structural responses under various earthquakes. In addition, the results obtained mentioned that using nonlinear viscous dampers further reduces the seismic responses of the structures as compared to linear viscous dampers.

International Journal of Engineering (IJE) , 2023

Seismic excitation can cause significant energy to be released within structures. By using specia... more Seismic excitation can cause significant energy to be released within structures. By using special devices, this energy can be consumed and dissipated without deforming structural members significantly. Due to this, structural damage is minimized, casualties are prevented during earthquakes, and structures are extended in their useful life. Over the past five decades, it has been widely acknowledged that steel yielding dampers are among the best energy dissipation devices. It has been stated that the hysteretic behavior of steel yielding dampers could vary slightly depending on their geometry. From a practical point of view, they are suitable for the improvement of seismic safety in new and existing structures. The purpose of this paper is to present a review related to steel yielding dampers, their development, various types, and applications, in order to help understand the role of these dampers in improving the seismic performance of structures. In terms of their shape, steel yielding dampers can be categorized as steel plate dampers, pipe dampers, curved dampers, and slit dampers. The most common use of steel plate, such as ADAS and TADAS, and pipe dampers is within braced frames, whereas U-shaped, J-shaped, and S-shaped dampers are mostly seen in frames with chevron bracing. Steel curved dampers with a 60° angle in a steel-braced frame, on the other hand, provide the best energy dissipation and frame strength. In this direction, until today, steel slit dampers have been found to be the most commonly used steel yielding dampers.

Research on Engineering Structures and Materials, 2023

Over the past two decades the effects of different admixtures have been investigated on mechanica... more Over the past two decades the effects of different admixtures have been investigated on mechanical properties and durability of engineered cementitious composites (ECC). Despite this, materials such as silica fume and zeolite have not been thoroughly investigated. The present study was designed and implemented to evaluate the effects of silica fume, zeolite, and blast furnace slag (BFS) on engineered cementitious composites and to compare the mechanical properties and durability of the polyvinyl alcohol-ECC (PVA-ECC) and polypropylene-ECC (PP-ECC) specimens. For this purpose, specimens were subjected to adverse conditions in a 5% magnesium sulfate solution and lab conditions as the reference treatment to measure the post-treatment variations in their compressive strength, flexural strength, and mid-span deflection (MSD). Results demonstrated that PP-ECC was not only easier to manufacture but outperformed PVA-ECC in some respects as well. It was also observed that MSD increased in the PVA-ECC specimens but declined in the PP-ECC ones under identical increments in their BFS contents. Finally, all the specimens maintained under the lab conditions displayed the best performance in terms of strength and durability when 3% silica fume was added to their mixtures while the same addition led to the worst performance in the sulfate medium.

Innovative Infrastructure Solutions

Journal of Constructional Steel Research

Australian Journal of Structural Engineering

Journal of Sustainable Cement-Based Materials, 2020

In this paper, the effects of the combined usage of micro-silica (MSi) and/or nanosilica (NSi) on... more In this paper, the effects of the combined usage of micro-silica (MSi) and/or nanosilica (NSi) on the drying shrinkage and compressive strength of the self-compacting concrete (SCC) were investigated. For this purpose, twenty-four types of the SCC mixes made with w/b ratios of 0.35, 0.40, and 0.45 and different percentages of MSi and/or NSi were applied in this research. The replacement ratios included 10% of MSi, 1, 2 or 3% of NSi, 9% MSi þ 1% NSi, 8% MSi þ 2% NSi, and 7% MSi þ 3% NSi. The obtained results revealed that the combined use of 9% MSi þ 1% NSi reduced the 150-day drying shrinkage of the SCC up to 17%, while it increased the 90-day compressive strength of it by 38%, as compared to the control sample. Moreover, it was found that replacing cement by MSi and NSi led to certain synergistic effects and their combination was stronger than the sums of the individual uses.

Asian Journal of Civil Engineering, 2020

This paper presents the combined effects of micro-SiO 2 (MSi) and nano-SiO 2 (NSi) on the water p... more This paper presents the combined effects of micro-SiO 2 (MSi) and nano-SiO 2 (NSi) on the water permeability and absorption of the self-consolidating concrete (SCC). To this aim, eight mixes of the SCC were created with w/b ratio of 0.45 and various proportions of NSi and/or MSi as following; 10% MSi, 1, 2 or 3% NSi, 9% MSi + 1% NSi, 8% MSi + 2% NSi, and 7% MSi + 3% NSi. Consequently, the experimental study showed that the combination of MSi and NSi had a good effect on the water penetration resistance of the SCC. The combination of 9% MSi + 1% NSi lowered the water penetration depth of the SCC nearly 58% and the short-term and total water absorption by approximately 23% and 30%, respectively. The combined addition of MSi and NSi could be more effective; as a result, the microstructure of the SCC would be more uniform and compact, thereby enhancing the water resistance.

The existing design formulas have provided significantly convenient tools to practical engineers ... more The existing design formulas have provided significantly convenient tools to practical engineers in determining the damping coefficients of the supplemental diagonal brace, K brace, upper toggle brace, and lower toggle brace. These formulas take into account the relative vertical and horizontal deformation between the two ends of a viscous damper installed in a frame panel so that the axial deformation of the damper and thus the dissipated energy by the damper can be better captured. In this paper, a mathematical formula is proposed for the internal and external Scissor-Jack brace damper system in structure with the relative vertical and horizontal deformation between the two ends of a viscous damper.