Easy mixing and placement of concrete and ultimate performance of structural member regard to its... more Easy mixing and placement of concrete and ultimate performance of structural member regard to its cost is one of the important factor in concrete structures. This paper offers an innovative solution to enhance the workability of the core concrete of concrete filled steel tube (CFST) without using additives. This solution can be used for both passive and active CFTs. This study was performed in two phases. In the first phase, high performance concrete (HPC) mixture was introduced and compressive strength of this type of concrete was measured in order to investigate the efficiency of proposed mixture. In the second phase, the active and passive CFTs, with both conventional concrete (CC) and HPC mixtures were built and their flexural behavior was studied. The flexural capacity, energy absorption, flexibility and failure mode of the confined specimens as well as cracking pattern of the concrete core at the failure point are evaluated in this study. Obtained results showed the effectiven...
Nowadays, as a result of increased terrorist and bomb attacks throughout the globe in the vicinit... more Nowadays, as a result of increased terrorist and bomb attacks throughout the globe in the vicinity of strategic buildings, designing these structures against impact loads, particularly the blast-related ones, has been taken into more consideration. The current procedure for designing the structure against an explosion is a design against the local failure of the current elements in the first step and then, in the next step, against local damage as well as tactful thinking to prevent this damage from spreading to other parts of the structure. The present research investigates the impacts of explosives, derived from probable terror–stricken scenarios inside and outside a strategic four-story steel building with a special moment frame system. Then, the resistive capacity of the damaged building (due to blast) has been evaluated against the progressive collapse, and finally, the rate of the collapse risk and the reliability of the structure have been obtained by presenting a probable me...
Journal of the Croatian Association of Civil Engineers, 2019
The aim of this study is to investigate the effect of active and passive confinement on the flexu... more The aim of this study is to investigate the effect of active and passive confinement on the flexural behaviour of concrete-filled steel tubes. Three-point flexural test is carried out on twelve confined specimens. The main variable parameters are: tube diameter to thickness ratio (20, 30, and 60), compressive strength of concrete core (15 MPa and 45 MPa), and type of confinement (active or passive). The flexural capacity, energy absorption, flexibility and failure mode of confined specimens, as well as the cracking pattern of concrete core at failure point, are evaluated in this study. The results show that active confinement leads to lower ductile behaviour in specimens with higher strength of concrete core.
Reinforcement and strengthening of reinforced concrete beams by unbounded external reinforcement ... more Reinforcement and strengthening of reinforced concrete beams by unbounded external reinforcement is one of the methods of fortification used after loading and prior to failure of the beams. This method is used in different forms to strengthen members of reinforced concrete structures. To investigate the effect of fortification on cracked reinforced concrete beams, numbers of reinforced concrete beams were selected for testing. Strengthening was examined by attaching external reinforcing bars on both sides of the beams, at the level of internal flexural tensile reinforcement and by means of deflectors. The investigation was carried out through experimental data analysis and modeling using ANSYS finite element structural software. The results showed that the method of fortification used has increased the flexural capacity of the beams. It was also concluded that this method is suitable for strengthening of beams under their dead loads.
Attacking city centers with pack portable bombs has become one of the regular terrorist attacks a... more Attacking city centers with pack portable bombs has become one of the regular terrorist attacks around the world. In these situations, life losses and injuries can be caused from various sources such as direct blast effects, structural collapse, debris impact, fire, and smoke. Casualties could increase when indirect effects are combined with closed exits or timely evacuation. So, calculating the annual risk of the structural collapses resulting from extreme loading conditions is subjected to many efforts. In this paper, the annual risk of blast-induced progressive structural collapse is calculated. The blast fragility is also calculated by a simulation procedure which generate possible blast configuration, and finally kinematic plastic limit analysis is used to verify the structural stability under gravity loading. As a case study, the blast fragility and the annual risk of collapse of a four-storey steel building are calculated.
Easy mixing and placement of concrete and ultimate performance of structural member regard to its... more Easy mixing and placement of concrete and ultimate performance of structural member regard to its cost is one of the important factor in concrete structures. This paper offers an innovative solution to enhance the workability of the core concrete of concrete filled steel tube (CFST) without using additives. This solution can be used for both passive and active CFTs. This study was performed in two phases. In the first phase, high performance concrete (HPC) mixture was introduced and compressive strength of this type of concrete was measured in order to investigate the efficiency of proposed mixture. In the second phase, the active and passive CFTs, with both conventional concrete (CC) and HPC mixtures were built and their flexural behavior was studied. The flexural capacity, energy absorption, flexibility and failure mode of the confined specimens as well as cracking pattern of the concrete core at the failure point are evaluated in this study. Obtained results showed the effectiven...
Nowadays, as a result of increased terrorist and bomb attacks throughout the globe in the vicinit... more Nowadays, as a result of increased terrorist and bomb attacks throughout the globe in the vicinity of strategic buildings, designing these structures against impact loads, particularly the blast-related ones, has been taken into more consideration. The current procedure for designing the structure against an explosion is a design against the local failure of the current elements in the first step and then, in the next step, against local damage as well as tactful thinking to prevent this damage from spreading to other parts of the structure. The present research investigates the impacts of explosives, derived from probable terror–stricken scenarios inside and outside a strategic four-story steel building with a special moment frame system. Then, the resistive capacity of the damaged building (due to blast) has been evaluated against the progressive collapse, and finally, the rate of the collapse risk and the reliability of the structure have been obtained by presenting a probable me...
Journal of the Croatian Association of Civil Engineers, 2019
The aim of this study is to investigate the effect of active and passive confinement on the flexu... more The aim of this study is to investigate the effect of active and passive confinement on the flexural behaviour of concrete-filled steel tubes. Three-point flexural test is carried out on twelve confined specimens. The main variable parameters are: tube diameter to thickness ratio (20, 30, and 60), compressive strength of concrete core (15 MPa and 45 MPa), and type of confinement (active or passive). The flexural capacity, energy absorption, flexibility and failure mode of confined specimens, as well as the cracking pattern of concrete core at failure point, are evaluated in this study. The results show that active confinement leads to lower ductile behaviour in specimens with higher strength of concrete core.
Reinforcement and strengthening of reinforced concrete beams by unbounded external reinforcement ... more Reinforcement and strengthening of reinforced concrete beams by unbounded external reinforcement is one of the methods of fortification used after loading and prior to failure of the beams. This method is used in different forms to strengthen members of reinforced concrete structures. To investigate the effect of fortification on cracked reinforced concrete beams, numbers of reinforced concrete beams were selected for testing. Strengthening was examined by attaching external reinforcing bars on both sides of the beams, at the level of internal flexural tensile reinforcement and by means of deflectors. The investigation was carried out through experimental data analysis and modeling using ANSYS finite element structural software. The results showed that the method of fortification used has increased the flexural capacity of the beams. It was also concluded that this method is suitable for strengthening of beams under their dead loads.
Attacking city centers with pack portable bombs has become one of the regular terrorist attacks a... more Attacking city centers with pack portable bombs has become one of the regular terrorist attacks around the world. In these situations, life losses and injuries can be caused from various sources such as direct blast effects, structural collapse, debris impact, fire, and smoke. Casualties could increase when indirect effects are combined with closed exits or timely evacuation. So, calculating the annual risk of the structural collapses resulting from extreme loading conditions is subjected to many efforts. In this paper, the annual risk of blast-induced progressive structural collapse is calculated. The blast fragility is also calculated by a simulation procedure which generate possible blast configuration, and finally kinematic plastic limit analysis is used to verify the structural stability under gravity loading. As a case study, the blast fragility and the annual risk of collapse of a four-storey steel building are calculated.
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