The Experts below are selected from a list of 48 Experts worldwide ranked by ideXlab platform

Tazarv Mostafa - One of the best experts on this subject based on the ideXlab platform.

  • Next Generation of Bridge Columns for Accelerated Bridge Construction in High Seismic Zones
    9999
    Co-Authors: Tazarv Mostafa, Saiidi, Mehdi S.
    Abstract:

    Report No. CCEER-14-06Accelerated bridge construction (ABC) utilizes advanced planning, new construction techniques, and innovative detailing to facilitate construction. ABC offers many advantages over conventional construction, the most important of which is the reduction of onsite construction time. Even though ABC has been widely used in low seismic regions of the country mostly in superstructure, application of ABC in seismic areas has been limited due to the lack of seismic performance data regarding substructure connections. The main objective of this study was to develop new ABC connections for bridge columns using novel detailing and advanced materials. Three low-damage materials were incorporated: ultra-high performance concrete (UHPC), Nickel-Titanium shape memory alloy (NiTi SMA), and engineered cementitious composite (ECC). Furthermore, two types of mechanical bar splices, grouted coupler and headed bar coupler, were utilized. UHPC-filled duct connections were developed and evaluated through 14 pullout tests. A new detailing was proposed for grouted coupler column end connections to enhance the drift capacity. Three half-scale Precast column models were tested under slow reversed cyclic loading, each with a new Precast Element connection or low-damage plastic hinge. A material model was developed for reinforcing superelastic NiTi SMA bars. Furthermore, new simple methods were developed to account for bond-slip effects and bar debonding effects in analytical models of reinforced concrete members. It was found that bar bond strength in UHPC is eight times higher than that in conventional concrete. UHPC-filled duct connections exhibited no damage even under 12% drift ratio cycles. The displacement capacity and displacement ductility capacity for the grouted coupler column were respectively increased by 47 and 56% compared to grouted coupler column models investigated previously. Longitudinal bar debonding allowed spread of yielding and prevented premature failure of reinforcements in UHPC-filled duct connections and grouted coupler column pedestal. The SMA-reinforced ECC column showed superior seismic performance compared to a conventional column in which the plastic hinge damage was limited to only ECC cover spalling even under 12% drift ratio cycles. The column residual displacements were 79% lower than CIP residual displacements on average due to the superelastic NiTi SMA longitudinal reinforcement, and higher base shear capacity and higher displacement capacity were observed. The analytical modeling methods were simple and sufficiently accurate for general design and analyses of Precast components proposed in the present study. The proposed symmetrical material model for reinforcing NiTi superelastic SMA was found to be a viable alternative to the more complex asymmetrical model. Extensive experimental and analytical investigations performed in the present study led to a new generation of ABC bridge columns in which columns can be built in relatively short time but the seismic performance of these columns is equal or better than columns that are built cast-in-place with conventional materials

  • Next Generation of Bridge Columns for Accelerated Bridge Construction in High Seismic Zones
    2018
    Co-Authors: Tazarv Mostafa
    Abstract:

    Accelerated bridge construction (ABC) utilizes advanced planning, new construction techniques, and innovative detailing to facilitate construction. ABC offers many advantages over conventional construction, the most important of which is the reduction of onsite construction time. Even though ABC has been widely used in low seismic regions of the country mostly in superstructure, application of ABC in seismic areas has been limited due to the lack of seismic performance data regarding substructure connections. The main objective of this study was to develop new ABC connections for bridge columns using novel detailing and advanced materials. Three low-damage materials were incorporated: ultra-high performance concrete (UHPC), Nickel-Titanium shape memory alloy (NiTi SMA), and engineered cementitious composite (ECC). Furthermore, two types of mechanical bar splices, grouted coupler and headed bar coupler, were utilized. UHPC-filled duct connections were developed and evaluated through 14 pullout tests. A new detailing was proposed for grouted coupler column end connections to enhance the drift capacity. Three half-scale Precast column models were tested under slow reversed cyclic loading, each with a new Precast Element connection or low-damage plastic hinge. A material model was developed for reinforcing superelastic NiTi SMA bars. Furthermore, new simple methods were developed to account for bond-slip effects and bar debonding effects in analytical models of reinforced concrete members. It was found that bar bond strength in UHPC is eight times higher than that in conventional concrete. UHPC-filled duct connections exhibited no damage even under 12% drift ratio cycles. The displacement capacity and displacement ductility capacity for the grouted coupler column were respectively increased by 47 and 56% compared to grouted coupler column models investigated previously. Longitudinal bar debonding allowed spread of yielding and prevented premature failure of reinforcements in UHPC-filled duct connections and grouted coupler column pedestal. The SMA-reinforced ECC column showed superior seismic performance compared to a conventional column in which the plastic hinge damage was limited to only ECC cover spalling even under 12% drift ratio cycles. The column residual displacements were 79% lower than CIP residual displacements on average due to the superelastic NiTi SMA longitudinal reinforcement, and higher base shear capacity and higher displacement capacity were observed. The analytical modeling methods were simple and sufficiently accurate for general design and analyses of Precast components proposed in the present study. The proposed symmetrical material model for reinforcing NiTi superelastic SMA was found to be a viable alternative to the more complex asymmetrical model. Extensive experimental and analytical investigations performed in the present study led to a new generation of ABC bridge columns in which columns can be built in relatively short time but the seismic performance of these columns is equal or better than columns that are built cast-in-place with conventional materials

Jawatankuasa Kerja Psm Uthm - One of the best experts on this subject based on the ideXlab platform.

  • Density and strength of foamed concrete: The influence on dynamic characteristics of lightweight profiled composite slabs.
    International Journal of Integrated Engineering Universiti Tun Hussein Onn Malaysia, 2018
    Co-Authors: Jawatankuasa Kerja Psm Uthm
    Abstract:

    This paper presents the experimental study on dynamic characteristics of lightweight profiled composite slabs. The density and strength of foamed concrete as topping material become the subject of interest. This type of floor system offers sustainable and reliable structural component in term of lightness, efficient construction processes and Precast Element. Although lightweight profiled composite slab may not a new thing in the construction industry, the under standing on the dynamic characteristics in term of natural frequency, damping ratio and mode shape are still ambiguous. Slab specimens,made of foamed concrete and Peva 45 steel corrugated deck,were fabricated with size of 840mm width, 1800mm length and 125mm thickness. The density of foamed concrete varies from 1400kg/m3 to 1800kg/m3.Within this range,foamed concrete has the compressive strength around 15.43MPato32.23 MPa and the tensile strength approximately 1.06 MPa to 1.97 MPa.The natural frequency was observed to decrease with the increment of density and strength of foamed concrete.The natural frequency of lightweight composite slabis around 30Hz to 35Hz. Meanwhile, the damping ratio is considered quite high at the range of 3% to 5%wherelow density of foamed concrete gave more advantage in dissipating vibration within short period. The mode shape was visually obtained using MEScope and represents the bending behaviour

Kowlowski Marcin - One of the best experts on this subject based on the ideXlab platform.

  • Density and Strength of Foamed Concrete: The Influence on Dynamic Characteristics of Lightweight Profiled Composite Slabs
    'Penerbit UTHM', 2019
    Co-Authors: Rum, Rahmat Hidayat Mohammed, Norhalim, Arnie Farhana, Jaini, Zainorizuan Mohd, Abd Ghafar, Nor Hayati, Kowlowski Marcin
    Abstract:

    This paper presents the experimental study on dynamic characteristics of lightweight profiled composite slabs. The density and strength of foamed concrete as topping material become the subject of interest.  This type of floor system offers sustainable and reliable structural component in term of lightness, efficient construction processes and Precast Element. Although lightweight profiled composite slab may not new thing in construction industry, the understand on dynamic characteristics in term of natural frequency, damping ratio and mode shape are still ambiguous. Lightweight composite slabs made of foamed concrete and Peva45 steel corrugated deck were fabricated with size of 840 mm width, 1800 mm length and 125 mm thickness. The density of foamed concrete is varied at 1400 kg/m3, 1600 kg/m3 and 1800 kg/m3. The cube test revealed that the compression strength of foamed concrete is 15.43 MPa, 22.97 MPa and 32.23 MPa for density 1400 kg/m3, 1600 kg/m3 and 1800 kg/m3 respectively. The natural frequency was observed to decrease with the increment of density and strength of foamed concrete. The natural frequency of lightweight composite slabs is around 30Hz to 35Hz. Meanwhile, the damping ratio is considered quite high at the range of 3% to 5%, where low density of foamed concrete gave more advantage in dissipating vibration within short period. The mode shape was visually obtained using MEScope and represents the bending behaviour

Saiidi, Mehdi S. - One of the best experts on this subject based on the ideXlab platform.

  • Next Generation of Bridge Columns for Accelerated Bridge Construction in High Seismic Zones
    9999
    Co-Authors: Tazarv Mostafa, Saiidi, Mehdi S.
    Abstract:

    Report No. CCEER-14-06Accelerated bridge construction (ABC) utilizes advanced planning, new construction techniques, and innovative detailing to facilitate construction. ABC offers many advantages over conventional construction, the most important of which is the reduction of onsite construction time. Even though ABC has been widely used in low seismic regions of the country mostly in superstructure, application of ABC in seismic areas has been limited due to the lack of seismic performance data regarding substructure connections. The main objective of this study was to develop new ABC connections for bridge columns using novel detailing and advanced materials. Three low-damage materials were incorporated: ultra-high performance concrete (UHPC), Nickel-Titanium shape memory alloy (NiTi SMA), and engineered cementitious composite (ECC). Furthermore, two types of mechanical bar splices, grouted coupler and headed bar coupler, were utilized. UHPC-filled duct connections were developed and evaluated through 14 pullout tests. A new detailing was proposed for grouted coupler column end connections to enhance the drift capacity. Three half-scale Precast column models were tested under slow reversed cyclic loading, each with a new Precast Element connection or low-damage plastic hinge. A material model was developed for reinforcing superelastic NiTi SMA bars. Furthermore, new simple methods were developed to account for bond-slip effects and bar debonding effects in analytical models of reinforced concrete members. It was found that bar bond strength in UHPC is eight times higher than that in conventional concrete. UHPC-filled duct connections exhibited no damage even under 12% drift ratio cycles. The displacement capacity and displacement ductility capacity for the grouted coupler column were respectively increased by 47 and 56% compared to grouted coupler column models investigated previously. Longitudinal bar debonding allowed spread of yielding and prevented premature failure of reinforcements in UHPC-filled duct connections and grouted coupler column pedestal. The SMA-reinforced ECC column showed superior seismic performance compared to a conventional column in which the plastic hinge damage was limited to only ECC cover spalling even under 12% drift ratio cycles. The column residual displacements were 79% lower than CIP residual displacements on average due to the superelastic NiTi SMA longitudinal reinforcement, and higher base shear capacity and higher displacement capacity were observed. The analytical modeling methods were simple and sufficiently accurate for general design and analyses of Precast components proposed in the present study. The proposed symmetrical material model for reinforcing NiTi superelastic SMA was found to be a viable alternative to the more complex asymmetrical model. Extensive experimental and analytical investigations performed in the present study led to a new generation of ABC bridge columns in which columns can be built in relatively short time but the seismic performance of these columns is equal or better than columns that are built cast-in-place with conventional materials

Rum, Rahmat Hidayat Mohammed - One of the best experts on this subject based on the ideXlab platform.

  • Density and Strength of Foamed Concrete: The Influence on Dynamic Characteristics of Lightweight Profiled Composite Slabs
    'Penerbit UTHM', 2019
    Co-Authors: Rum, Rahmat Hidayat Mohammed, Norhalim, Arnie Farhana, Jaini, Zainorizuan Mohd, Abd Ghafar, Nor Hayati, Kowlowski Marcin
    Abstract:

    This paper presents the experimental study on dynamic characteristics of lightweight profiled composite slabs. The density and strength of foamed concrete as topping material become the subject of interest.  This type of floor system offers sustainable and reliable structural component in term of lightness, efficient construction processes and Precast Element. Although lightweight profiled composite slab may not new thing in construction industry, the understand on dynamic characteristics in term of natural frequency, damping ratio and mode shape are still ambiguous. Lightweight composite slabs made of foamed concrete and Peva45 steel corrugated deck were fabricated with size of 840 mm width, 1800 mm length and 125 mm thickness. The density of foamed concrete is varied at 1400 kg/m3, 1600 kg/m3 and 1800 kg/m3. The cube test revealed that the compression strength of foamed concrete is 15.43 MPa, 22.97 MPa and 32.23 MPa for density 1400 kg/m3, 1600 kg/m3 and 1800 kg/m3 respectively. The natural frequency was observed to decrease with the increment of density and strength of foamed concrete. The natural frequency of lightweight composite slabs is around 30Hz to 35Hz. Meanwhile, the damping ratio is considered quite high at the range of 3% to 5%, where low density of foamed concrete gave more advantage in dissipating vibration within short period. The mode shape was visually obtained using MEScope and represents the bending behaviour