Iraq is one of the richest countries, especially in the Middle East and generally in the world, i... more Iraq is one of the richest countries, especially in the Middle East and generally in the world, in natural resources such as water due to existing of Tigris and Euphrates rivers, tributaries branches, marshlands and lakes which are already affected by climate change. Thus, Dokan and Darbandikhan lakes (in the northern of Iraq) have been monitored and studied throughout the past eighteen years (1999-2016) in term of area and average monthly rainfall (AMR) of feeding basin to Figure out the effect of historical climate change. Landsat images satellite (5, 7, and 8) types were used to collect 36 satellite images for the study area (18 images for each lake), ArcGIS 10.2 program was used as well to create a map of the water drainage networks. The results showed that the average variation in AMR of feeding basins of the two lakes was about 1.12. Also, overall average area of Darbandikhan and Dokan lakes was about 71.52 km 2 and 168.86 km 2 respectively. In addition, overall average AMR of Darbandikhan and Dokan lakes was 1.02 km 3 and 0.92 km 3 consecutively. In addition, the correlation coefficient between area and AMR of feeding basin for Darbandikhan and Dokan Lakes was 75% and 90% respectively. Coefficient of variance (COV) has been found as well to be the lowest for Dokan Lake area, which was about 23% in comparison with Darbandikhan which was about 39%.
International Journal of Civil Engineering and Technology, Nov 30, 2018
Effect of structural links on seismic responses for a linked building system has been investigate... more Effect of structural links on seismic responses for a linked building system has been investigated in this paper by using finite element modeling technique. The linked building system in this study is represented by twin 40-story reinforced concrete frame-wall structures horizontally coupled by structural links. It is assumed that the two adjacent buildings were similar in this linked building system, so the two adjacent stories could be linked at the same height by an inter-building link. The linked building system is modeled as a rigid floor diaphragm for towers and as a beam for each link fixedly linked to the perimeter structural framework of the buildings. By employing earthquake time history excitation, the seismic responses of the twin towers were computed at different locations for the link. The responses of structures were evaluated and compared. The analysis outcomes indicated that the link could effectively change the structural responses of the linked building system. The Seismic structural responses have been decreased in some cases compared to the single tower, referring to the extra link stiffness as gathering the single tower to withstand seismic excitation. While the responses have been increased in other cases, attributing to the additional mass of link. Thus, in the design of seismic-resistant linked building systems, care must be taken. Particularly regarding properties of the link, specifically mass, stiffness, and location, as well as the link resistance with respect to the strength of the link and/or the structural elements composing the link to obviate undesired structural responses.
A B S T R A C T Steel fiber self-compacting concrete (SFSCC) is an innovative material that can f... more A B S T R A C T Steel fiber self-compacting concrete (SFSCC) is an innovative material that can flow underneath its own weight in the fresh state, thus eliminating any need for mechanical vibration and complexity of the formwork, and which employs the benefits of steel fiber addition in the hardened state. Hence, this study evaluated the performance of a self-compacting concrete (SCC) under the effect of filler addition and then investigated the effect of steel fiber (SF) addition on flexural behavior, splitting tensile strength, compressive strength, and modulus of elasticity. Fourteen reinforced concrete beams were tested under monotonic loads: two sets of six SCCs (with and without SFs) and two normal concretes (NCs). Ultimate capacity, deflection, crack pattern, and mode of failure were recorded. The present experimental and theoretical results were compared in accordance with ACI 318 codes to assess the applicability of the aforementioned methods to predict the flexural strength of SCC specimens. The results of the tests carried out on fresh concretes indicate excellent deformability without blocking. Moreover, the flexural strength in beams increases with increasing concrete compressive strength, longitudinal steel reinforcement ratio, and SF amount.
This paper presents results of analytical evaluation conducted on beam-column connection using no... more This paper presents results of analytical evaluation conducted on beam-column connection using nonlinear static pushover analysis (NSPA) process. The aim of using this technique is to investigate the efficiency of the configuration used in conventional steel beam-column connections. In this research work the beam was subjected to two different applied loads; which are concentrated load and uniform distributed load. Two case scenarios have been studied to check the stability of connections while distributed load increased by a factor of 2. The beam is connected to the column by a fully penetration weld. Numerous correlations have been investigated such as base shear vs. displacement, displacement vs. time, and base shear vs. time. The numerical result indicated that joint capacity for both cases show the same behavior in the elastic range. However its behavior changes in the plastic range. The results showed that with increasing (doubled) the applied load on the beam-column connection the base shear and peak displacement do not change. Moreover, for studying the yield point of welded beam-column connection, the model analysis " finite element modeling (FEM) software " was conducted.
Excessive fatigue deterioration is usually experienced when Reinforced Concrete structural elemen... more Excessive fatigue deterioration is usually experienced when Reinforced Concrete structural elements are subjected to loadings. This emphasizes the desire to strengthen as well as improve the fatigue performance and extend the fatigue life of RC structural components particularly beams. During the last few decades, strengthening of concrete structural elements by fibre-reinforced polymer (FRP) has become a widely used technique where high strength is needed for carrying heavy loads or repairing is done due to fatigue cracking, failure modes and or corrosion. This paper reviews various aspects of RC beams strengthened with FRP. This topic has not been covered comprehensively in previous studies, whereas the technology has been modified rapidly in the recent past. It highlights aspects such as surface preparation, adhesive curing, finite element (FE) simulation, fatigue performance as well as the failure modes of RC beams retrofitted with FRP. This technique eliminates and or reduces the crack growth rate, delay initial cracking, decline the stiffness decay with residual deflection and extend the fatigue life of RC beams. The best strengthening option in this case is pre-stressed carbon fibre-reinforced polymer (CFRP).
Hollow sections have been increasingly applied in the construction of buildings, bridges, offshor... more Hollow sections have been increasingly applied in the construction of buildings, bridges, offshore structures, and towers for passing electrical and mechanical pipes or other utilities. Torsion caused by external force is a weakness of hollow sections that is rarely investigated. In particular, the behavior of hollow sections with high-strength concrete (HSC) and ultra-high performance concrete (UHPC) remains poorly studied. This study aims to examine the behavior of a reinforced concrete hollow beam with opening and compare it with a hollow beam without opening. The hollow beam with an opening is modeled using the finite element method and analyzed under torsional, flexural, and cyclic loading with HSC and UHPC materials. The effect of the opening section size on the behavior of hollow beam is also evaluated. The openings created in the web of hollow beams led to a decrease in beam capacity although the hollow beam with small opening can carry almost the same load as that of hollow beam without an opening. The result also shows that the capacity of UHPC beams for twisting is twice that of HSC beams.
Iraq is one of the richest countries, especially in the Middle East and generally in the world, i... more Iraq is one of the richest countries, especially in the Middle East and generally in the world, in natural resources such as water due to existing of Tigris and Euphrates rivers, tributaries branches, marshlands and lakes which are already affected by climate change. Thus, Dokan and Darbandikhan lakes (in the northern of Iraq) have been monitored and studied throughout the past eighteen years (1999-2016) in term of area and average monthly rainfall (AMR) of feeding basin to Figure out the effect of historical climate change. Landsat images satellite (5, 7, and 8) types were used to collect 36 satellite images for the study area (18 images for each lake), ArcGIS 10.2 program was used as well to create a map of the water drainage networks. The results showed that the average variation in AMR of feeding basins of the two lakes was about 1.12. Also, overall average area of Darbandikhan and Dokan lakes was about 71.52 km 2 and 168.86 km 2 respectively. In addition, overall average AMR of Darbandikhan and Dokan lakes was 1.02 km 3 and 0.92 km 3 consecutively. In addition, the correlation coefficient between area and AMR of feeding basin for Darbandikhan and Dokan Lakes was 75% and 90% respectively. Coefficient of variance (COV) has been found as well to be the lowest for Dokan Lake area, which was about 23% in comparison with Darbandikhan which was about 39%.
International Journal of Civil Engineering and Technology, Nov 30, 2018
Effect of structural links on seismic responses for a linked building system has been investigate... more Effect of structural links on seismic responses for a linked building system has been investigated in this paper by using finite element modeling technique. The linked building system in this study is represented by twin 40-story reinforced concrete frame-wall structures horizontally coupled by structural links. It is assumed that the two adjacent buildings were similar in this linked building system, so the two adjacent stories could be linked at the same height by an inter-building link. The linked building system is modeled as a rigid floor diaphragm for towers and as a beam for each link fixedly linked to the perimeter structural framework of the buildings. By employing earthquake time history excitation, the seismic responses of the twin towers were computed at different locations for the link. The responses of structures were evaluated and compared. The analysis outcomes indicated that the link could effectively change the structural responses of the linked building system. The Seismic structural responses have been decreased in some cases compared to the single tower, referring to the extra link stiffness as gathering the single tower to withstand seismic excitation. While the responses have been increased in other cases, attributing to the additional mass of link. Thus, in the design of seismic-resistant linked building systems, care must be taken. Particularly regarding properties of the link, specifically mass, stiffness, and location, as well as the link resistance with respect to the strength of the link and/or the structural elements composing the link to obviate undesired structural responses.
A B S T R A C T Steel fiber self-compacting concrete (SFSCC) is an innovative material that can f... more A B S T R A C T Steel fiber self-compacting concrete (SFSCC) is an innovative material that can flow underneath its own weight in the fresh state, thus eliminating any need for mechanical vibration and complexity of the formwork, and which employs the benefits of steel fiber addition in the hardened state. Hence, this study evaluated the performance of a self-compacting concrete (SCC) under the effect of filler addition and then investigated the effect of steel fiber (SF) addition on flexural behavior, splitting tensile strength, compressive strength, and modulus of elasticity. Fourteen reinforced concrete beams were tested under monotonic loads: two sets of six SCCs (with and without SFs) and two normal concretes (NCs). Ultimate capacity, deflection, crack pattern, and mode of failure were recorded. The present experimental and theoretical results were compared in accordance with ACI 318 codes to assess the applicability of the aforementioned methods to predict the flexural strength of SCC specimens. The results of the tests carried out on fresh concretes indicate excellent deformability without blocking. Moreover, the flexural strength in beams increases with increasing concrete compressive strength, longitudinal steel reinforcement ratio, and SF amount.
This paper presents results of analytical evaluation conducted on beam-column connection using no... more This paper presents results of analytical evaluation conducted on beam-column connection using nonlinear static pushover analysis (NSPA) process. The aim of using this technique is to investigate the efficiency of the configuration used in conventional steel beam-column connections. In this research work the beam was subjected to two different applied loads; which are concentrated load and uniform distributed load. Two case scenarios have been studied to check the stability of connections while distributed load increased by a factor of 2. The beam is connected to the column by a fully penetration weld. Numerous correlations have been investigated such as base shear vs. displacement, displacement vs. time, and base shear vs. time. The numerical result indicated that joint capacity for both cases show the same behavior in the elastic range. However its behavior changes in the plastic range. The results showed that with increasing (doubled) the applied load on the beam-column connection the base shear and peak displacement do not change. Moreover, for studying the yield point of welded beam-column connection, the model analysis " finite element modeling (FEM) software " was conducted.
Excessive fatigue deterioration is usually experienced when Reinforced Concrete structural elemen... more Excessive fatigue deterioration is usually experienced when Reinforced Concrete structural elements are subjected to loadings. This emphasizes the desire to strengthen as well as improve the fatigue performance and extend the fatigue life of RC structural components particularly beams. During the last few decades, strengthening of concrete structural elements by fibre-reinforced polymer (FRP) has become a widely used technique where high strength is needed for carrying heavy loads or repairing is done due to fatigue cracking, failure modes and or corrosion. This paper reviews various aspects of RC beams strengthened with FRP. This topic has not been covered comprehensively in previous studies, whereas the technology has been modified rapidly in the recent past. It highlights aspects such as surface preparation, adhesive curing, finite element (FE) simulation, fatigue performance as well as the failure modes of RC beams retrofitted with FRP. This technique eliminates and or reduces the crack growth rate, delay initial cracking, decline the stiffness decay with residual deflection and extend the fatigue life of RC beams. The best strengthening option in this case is pre-stressed carbon fibre-reinforced polymer (CFRP).
Hollow sections have been increasingly applied in the construction of buildings, bridges, offshor... more Hollow sections have been increasingly applied in the construction of buildings, bridges, offshore structures, and towers for passing electrical and mechanical pipes or other utilities. Torsion caused by external force is a weakness of hollow sections that is rarely investigated. In particular, the behavior of hollow sections with high-strength concrete (HSC) and ultra-high performance concrete (UHPC) remains poorly studied. This study aims to examine the behavior of a reinforced concrete hollow beam with opening and compare it with a hollow beam without opening. The hollow beam with an opening is modeled using the finite element method and analyzed under torsional, flexural, and cyclic loading with HSC and UHPC materials. The effect of the opening section size on the behavior of hollow beam is also evaluated. The openings created in the web of hollow beams led to a decrease in beam capacity although the hollow beam with small opening can carry almost the same load as that of hollow beam without an opening. The result also shows that the capacity of UHPC beams for twisting is twice that of HSC beams.
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Papers by Mahir M A H M O D Hason