Khaled Sennah - Academia.edu (original) (raw)

Papers by Khaled Sennah

Lecture notes in civil engineering, 2024

Proceedings of the International Conference on Civil, Structural and Transportation Engineering, Jun 1, 2024

This paper investigates the mechanical properties of rubberized fiber-reinforced concrete (RuFRC)... more This paper investigates the mechanical properties of rubberized fiber-reinforced concrete (RuFRC) incorporating synthetic macro-structural fibers made of recycled plastics and waste tyre rubber shreds. The effects of different percentages of fiber doses 0%, 0.25%, 0.5% and 1% on the compressive, tensile and flexural strength of RuFRC are examined. In addition, tyre rubber shreds are used to replace coarse aggregate by 10%, 20% and 30% by volume. It is found that the mechanical properties of RuFRC are significantly affected due to the variation of the fiber doses and rubber percentages. While the inclusion of fiber and rubber together decreases the compressive strength of concrete, the tensile strength of concrete is found to increase significantly.

Proceedings of the International Conference on Civil, Structural and Transportation Engineering, Jun 1, 2024

Similar to steel-reinforced concrete structures, traditional concrete bridge barriers reinforced ... more Similar to steel-reinforced concrete structures, traditional concrete bridge barriers reinforced with steel bars suffer a common problem which is the corrosion of steel reinforcement and related deteriorations which shorten their service life. The maintenance, rehabilitation, and replacement of existing bridge barriers suffering from steel corrosion are very costly. This paper proposes durable and crash-worthy rubberized fiber-reinforced concrete (RuFRC) bridge barriers incorporating synthetic macro-structural fibers made of recycled plastics and waste tyre rubber shreds and reinforced with stainless steel reinforcement bars to improve corrosion resistance. This study reports a series of tests carried out on the impact performance of the proposed crash barriers using pendulum tests replicating the vehicle impact load scenarios. The bridge barriers were made of 1% macro-synthetic fibers whereas the rubber shreds were used to replace coarse aggregate by 12%, 18%, 24% and 30%. The effects of various rubber percentages and the impact speed on the impact performance of the proposed bridge barriers are examined. It is found that increasing rubber percentages increases the displacement of the barriers, with a maximum 80% increase in the displacement observed in comparison to the control specimen when 24% rubber is used. The energy absorption capacity of the RuFRC barriers is found to be higher than the conventional control bridge barrier.

Proceedings of the International Conference on Civil, Structural and Transportation Engineering, Jun 1, 2024

This sensitivity study investigates the effect of intermittent construction joints on the moments... more This sensitivity study investigates the effect of intermittent construction joints on the moments, shear, and tensile forces on the barrier wall and deck slab overhang in slab-on-girder bridges due to transverse vehicle impact loads. This study used the threedimensional finite-element modeling of a 30 m long, TL-5, single-slope concrete barrier mounted over a 1 m length deck overhang. Spacing between intermittent expansion joints was taken at 3, 4, 5, and 6 m compared to the continuous barrier wall that equals the overhang length in the direction of traffic. The results from this research are pivotal in formulating robust empirical design equations in the future, marking a significant advancement in engineering practices for reliable bridge design. Results show that intermittent expansion joints, with spacings from 3 to 6 meters, cause an increase in the transverse moment at the inner side of the barrier wall for interior loads. However, the presence of these joints does not significantly alter the shear force at the barrier base or the tensile force at the inner side of the barrier wall, indicating that the primary impact of expansion joints is on the moment rather than shear or tensile forces. At the barrier end location, the presence of intermittent expansion joints over 3 m to 6 m spacings has an insignificant effect on the transverse moment and tensile force in the deck overhang at the inner side of the barrier wall (except for the 3 m spacing) and the shear force at the barrier base at the barrier end due to transverse vehicle impact load.

Engineering Failure Analysis, 2009

ABSTRACT

The structural insulated panel (SIP) is an engineered composite product composed of an insulating... more The structural insulated panel (SIP) is an engineered composite product composed of an insulating foam core sandwiched to provide the insulation and rigidity, and two face-skin materials to provide durability and strength. SIPs can also be used as permanent wood foundation (PWF) for basements in low-rise residential construction to save in the energy cost. The maximum deflection equation specified in the Canadian Standard for Engineering Design of Wood, CAN/CSA-O86.09 specifies expressions for the effects of short-term bending deflection on the PWF timber stud walls. PWF is subjected to gravity loads associated with lateral soil pressure. To use the available combined bending and axial compression equation for PWF design, it was observed that the soil pressure would cause short-term and long-term flexural creep deflection of the wall that would decrease the wall capacity. Information on the long-term creep behaviour of SIPs under sustained triangular loading, simulating soil pressure, is as yet unavailable. As such, this paper presents a summary of flexural creep tests conducted to determine the increase in SIP deflection under soil pressure over a period of eight months. Using the experimental data, the available mathematical and mechanical creep models were evaluated to predict the flexural creep constant (K) of SIP foundation wall subjected to soil pressure over a service life up to 75 years. A flexural creep constant was then proposed to determine the longterm eccentricity of gravity loading in the available combined bending and axial compression equation for PWF design.

The structural insulated panel (SIP) is an engineered composite product composed of an insulating... more The structural insulated panel (SIP) is an engineered composite product composed of an insulating foam core sandwiched to provide the insulation and rigidity, and two face-skin materials to provide durability and strength. SIPs can also be used as permanent wood foundation (PWF) for basements in low-rise residential construction to save in the energy cost. The maximum deflection equation specified in the Canadian Standard for Engineering Design of Wood, CAN/CSA-O86.09 specifies expressions for the effects of short-term bending deflection on the PWF timber stud walls. Information on the long-term creep behavior of SIPs under sustained triangular loading, simulating soil pressure, including effect of the change in ambient temperature and relative humidity is as yet unavailable. The long-term creep deflection for permanent wood foundation panels that is characterized as viscoelastic materials is highly affected by the change in ambient temperature and relative humidity. This paper reported the results from flexural creep experiments performed on two sets of different sizes of PWF made of structural-insulated foam-timber panels. In these tests, deflection, temperature and relative humidity were tracked for an eight-month period. The experimental findings were examined against existing creep models in the literature. Then, a creep model incorporating the effects of temperature and relative humidity on creep deflection was developed. Correlation between the proposed model and the experimental findings provides confidence on using the proposed model in the determination of the capacity of the PWF under combined gravity loading and sustained soil pressure as affected by temperature variation and relative humidity.

Proceedings of the International Conference on Civil, Structural and Transportation Engineering, Nov 1, 2020

The use of prefabricated elements and systems in bridge replacement (ABR) has recently been the s... more The use of prefabricated elements and systems in bridge replacement (ABR) has recently been the subject of much attention and interest amongst bridge jurisdictions in North America as a way of improving bridge construction and replacement of deteriorated bridges. Through mass production of the materials, the repeated use of forms, reduction of onsite construction time and labor by concentrating the construction effort in a fabrication facility rather than at the bridge site, significant economic benefits can be achieved. Issues related to work zone safety and traffic disruptions are also a major concern. A full-lane closure is very costly in busy urban highways because of the significant economic impact on commercial and industrial activities. As a result, prefabricated bridge technology is seen as a potential solution to many of these issues. Prefabricated elements and systems can be quickly assembled and could reduce design efforts, reduce the impact on the environment in the vicinity of the site, and minimize the delays and lane closure time and inconvenience to the traveling public, saving time and tax payers' money. Even at a higher initial cost, the use of prefabricated systems on bridges subjected to a high volume of traffic may be justified because excessive lane closure times can be avoided. This lecture presents the current state-of-the-art approach to the use of innovative prefabricated systems and elements in modern bridge construction. A summary of most recent ABR Guidelines and Specifications in Canada and USA will be covered. Also, the presentation will cover a variety of precast concrete girders, full-depth deck panels, abutment, piers and pile caps used to accelerate bridge construction. Moreover, a few of the latest precast connection details that have been implemented in Canada and USA using ultra-high performance fibre-reinforced concrete (UHPFRC) as connection filling material and non-corrosive glass fibre reinforced polymer (GFRP) bars as deck slab reinforcement will be covered. The use of stainless steel in replacing steel girders will be covered.

Elsevier eBooks, 2002

Publisher Summary A critical design stage for curved composite concrete deck-steel box girder bri... more Publisher Summary A critical design stage for curved composite concrete deck-steel box girder bridges occurs during casting the concrete bridge deck, when the non-composite steel box section must support the wet concrete and the entire construction loading. Although a composite box girder has a high torsional stiffness in the completed bridge, the open section during construction is relatively flexible in torsion. A horizontal truss system is usually installed at the top flange level to increase the torsional stiffness. Therefore, the aim of this chapter is to provide the practicing engineers with a better understanding of the structural behavior of such curved bridges under construction loading. This chapter presents a summary of an extensive parametric study, using the finite-element method, on which straight and curved single-cell steel bridges with different configurations are analyzed. The key parameters considered in the chapter include degree of curvature, vertical cross-bracing system, and top horizontal bracing system. This chapter focuses on the stresses and deflections at the mid-span section as well as support reactions. Since most current design methods neglect the effects of girder bending and torsional stresses on the horizontal and vertical bracings, the chapter gives particular attention to the horizontal forces in the top horizontal bracings as well as the vertical bracings due to pure bending or combined bending and torsion.

Proceedings of the International Conference on Civil, Structural and Transportation Engineering, Jun 1, 2022

This paper develops a simplified fiber-based numerical model to investigate the performance of ci... more This paper develops a simplified fiber-based numerical model to investigate the performance of circular concrete-filled stainless steel tubular (CFSST) short columns subjected to axial loading. A new compressive concrete strength formula is developed based on the test data of CFSST columns. The accuracy of the numerical model is evaluated by comparing the ultimate axial capacity and axial load-strain curves of CFSST columns with a large test database. A parametric study is carried out to investigate the effects of geometry and material properties on the axial performance of CFSST columns.

Construction and Building Materials, 2023

World Academy of Science, Engineering and Technology, International Journal of Civil, Environmental, Structural, Construction and Architectural Engineering, Mar 12, 2014

Engineering Structures, Sep 1, 2022

Advances in Structural Engineering, Dec 16, 2019

Due to its structural efficiency, durability, and cost-effectiveness, ultra-high performance conc... more Due to its structural efficiency, durability, and cost-effectiveness, ultra-high performance concrete was utilized to build the first highway overpass bridge in China. The bridge was made of prestressed ultra-high performance concrete box girders of four continuous spans of 30 m each. As the original design of such bridge was observed to be somewhat conservative, its cross-sectional dimensions, in the form of the box girder wall thicknesses were optimized in this research to lower the material cost in future bridge construction. Then, a full-scale simply supported ultra-high performance concrete box girder of 30 m span, incorporating the new box girder wall thicknesses, was fabricated and then tested under static loading to obtain research data to justify the revised design. The loading system was designed to examine the flexural behavior of the girder using two concentrated loads symmetrically located at the mid-span. Experimental results show that the optimized girder has a favorable ductile behavior and excellent flexural strength, which can meet the design requirements for serviceability and ultimate limit states. A finite element model of the tested girder was developed, using ABAQUS software, and then was verified using the experimental findings. A parametric study was then conducted to investigate the influence of key parameters on the structural response, namely, the reinforcement ratio, the number of the prestressing wires, and the web thickness. Recommendations on minimum and maximum compressive strength and tensile property of ultra-high performance concrete were proposed. Also, a simplified calculation method of prestressed ultra-high performance concrete box girder was developed based on a verified strain and stress diagrams for cross-sectional analysis. The proposed methodology can be used in future practice with confidence.

Materials and Structures, Jul 29, 2023

High-modulus (HM) ribbed-surface glass fiber reinforced polymer (GFRP) bars have recently been us... more High-modulus (HM) ribbed-surface glass fiber reinforced polymer (GFRP) bars have recently been used in concrete bridge decks to avoid corrosion of steel reinforcement resulting from the use of de-icing salts in winter times in North America. Recently, prefabricated full-depth deck panels (FDDPs), made of normal strength concrete or high performance concrete and reinforced with GFRP bars, are used in Canada to acceleration bridge construction. The FDDPs are connected through panel-to-panel and panel-to-girder connections. These connections are filled with joint-filled cementitious materials as ultra-high performance fiber-reinforced concrete (UHPFRC). This paper presents the experimental program to investigate the bond strength of the GFRP bars embedded into unconfined UHPFRC using pull-out testing, leading to the proper GFRP bar development length required to determine the width of the closure strip between connected slabs. The longitudinal GFRP/UHPFRC interface is influenced by (i) the development length-to-nominal diameter of the bar ratio, (ii) the concrete cover-to-bar diameter ratio and (iii) the development length-to-embedment depth ratio due to lugs or headed-end and (iv) concrete compressive strength. GFRP bars embedded into UHPFRC would rely less on the friction and adhesion of the interface, and more on the bearing of the lugs against the concrete. These bearing forces act at an angle to the axis of the bar, causing radial outward forces. Pullout failure of the GFRP/UHPFRC interface leads to shearing of the lugs and bar slippage from the headed-end. Adequate bond strength between the GFRP/UHPFRC interfaces is necessary for design of jointed PDDFs. Therefore, accurate predictions of development length and bond strength of straight or headed-end bars without passing through the high localized stresses due to flexural are essential for safe design.

Proceedings of the 2nd World Congress on Civil, Structural, and Environmental Engineering, Mar 1, 2023

The Canadian Highway Bridge Design Code, CHBDC, is based on limit states design principles and de... more The Canadian Highway Bridge Design Code, CHBDC, is based on limit states design principles and defines design loadings, load combinations and load factors, and detailed design criteria for the various materials and bridge types. CHBDC specifies simplified method of analysis of slab-on-girder bridges in lieu of conducting detailed refined analysis of the bridge structure. The 2019 version of CHBDC addressed the need for simplified method of analysis for prefabricated bridge systems for use in accelerated bridge construction and replacement. These bridges include the following shear-connected adjacent precast beam types: box beams, voided slab units, T-beams, Double-T beams, and Inverted-U beams. A summary of an experimental work on developed joint details between adjacent beams will be presented and compared to the specified transverse factored applied vertical shear force between shear-connected beams for shear key design. A method for the design of deck slab cantilever overhang due to (i) truck loading conditions and (ii) vehicle collision loads applied to concrete barriers mounted integrally with the deck overhang. A design methodology for a concrete section subjected to combined bending moment and axial force will be presented. Finally, a new simplified method of analysis is provided for determining the factored flexural resistance of steel-reinforced concrete barrier to transverse traffic barrier load based on a trapezoidal yieldline failure pattern.

Advances in Structural Engineering

A square concrete-filled double steel tubular (CFDST) column composed of a circular core concrete... more A square concrete-filled double steel tubular (CFDST) column composed of a circular core concrete-filled tube offers the advantages of both square and circular concrete-filled steel tubular (CFST) columns. However, limited tests were performed to investigate the axial performance of CFDST slender columns. This paper investigates the behavior and design of square CFDST slender columns subjected to concentric loading. A total of eight columns, including six CFDST slender columns and two CFDST short columns were tested under concentric loading. The test parameter includes the slenderness ratio of the columns and the thickness of the inner tube. The ultimate load, failure modes and axial load-deflection relationships of CFDST slender columns are presented. It was observed that square CFDST slender columns failed due to the overall buckling of the columns together with the localized buckling of the steel tube and concrete crushing. Increasing the slenderness ratio and decreasing the thic...

Lecture notes in civil engineering, 2024

Proceedings of the International Conference on Civil, Structural and Transportation Engineering, Jun 1, 2024

This paper investigates the mechanical properties of rubberized fiber-reinforced concrete (RuFRC)... more This paper investigates the mechanical properties of rubberized fiber-reinforced concrete (RuFRC) incorporating synthetic macro-structural fibers made of recycled plastics and waste tyre rubber shreds. The effects of different percentages of fiber doses 0%, 0.25%, 0.5% and 1% on the compressive, tensile and flexural strength of RuFRC are examined. In addition, tyre rubber shreds are used to replace coarse aggregate by 10%, 20% and 30% by volume. It is found that the mechanical properties of RuFRC are significantly affected due to the variation of the fiber doses and rubber percentages. While the inclusion of fiber and rubber together decreases the compressive strength of concrete, the tensile strength of concrete is found to increase significantly.

Proceedings of the International Conference on Civil, Structural and Transportation Engineering, Jun 1, 2024

Similar to steel-reinforced concrete structures, traditional concrete bridge barriers reinforced ... more Similar to steel-reinforced concrete structures, traditional concrete bridge barriers reinforced with steel bars suffer a common problem which is the corrosion of steel reinforcement and related deteriorations which shorten their service life. The maintenance, rehabilitation, and replacement of existing bridge barriers suffering from steel corrosion are very costly. This paper proposes durable and crash-worthy rubberized fiber-reinforced concrete (RuFRC) bridge barriers incorporating synthetic macro-structural fibers made of recycled plastics and waste tyre rubber shreds and reinforced with stainless steel reinforcement bars to improve corrosion resistance. This study reports a series of tests carried out on the impact performance of the proposed crash barriers using pendulum tests replicating the vehicle impact load scenarios. The bridge barriers were made of 1% macro-synthetic fibers whereas the rubber shreds were used to replace coarse aggregate by 12%, 18%, 24% and 30%. The effects of various rubber percentages and the impact speed on the impact performance of the proposed bridge barriers are examined. It is found that increasing rubber percentages increases the displacement of the barriers, with a maximum 80% increase in the displacement observed in comparison to the control specimen when 24% rubber is used. The energy absorption capacity of the RuFRC barriers is found to be higher than the conventional control bridge barrier.

Proceedings of the International Conference on Civil, Structural and Transportation Engineering, Jun 1, 2024

This sensitivity study investigates the effect of intermittent construction joints on the moments... more This sensitivity study investigates the effect of intermittent construction joints on the moments, shear, and tensile forces on the barrier wall and deck slab overhang in slab-on-girder bridges due to transverse vehicle impact loads. This study used the threedimensional finite-element modeling of a 30 m long, TL-5, single-slope concrete barrier mounted over a 1 m length deck overhang. Spacing between intermittent expansion joints was taken at 3, 4, 5, and 6 m compared to the continuous barrier wall that equals the overhang length in the direction of traffic. The results from this research are pivotal in formulating robust empirical design equations in the future, marking a significant advancement in engineering practices for reliable bridge design. Results show that intermittent expansion joints, with spacings from 3 to 6 meters, cause an increase in the transverse moment at the inner side of the barrier wall for interior loads. However, the presence of these joints does not significantly alter the shear force at the barrier base or the tensile force at the inner side of the barrier wall, indicating that the primary impact of expansion joints is on the moment rather than shear or tensile forces. At the barrier end location, the presence of intermittent expansion joints over 3 m to 6 m spacings has an insignificant effect on the transverse moment and tensile force in the deck overhang at the inner side of the barrier wall (except for the 3 m spacing) and the shear force at the barrier base at the barrier end due to transverse vehicle impact load.

Engineering Failure Analysis, 2009

ABSTRACT

The structural insulated panel (SIP) is an engineered composite product composed of an insulating... more The structural insulated panel (SIP) is an engineered composite product composed of an insulating foam core sandwiched to provide the insulation and rigidity, and two face-skin materials to provide durability and strength. SIPs can also be used as permanent wood foundation (PWF) for basements in low-rise residential construction to save in the energy cost. The maximum deflection equation specified in the Canadian Standard for Engineering Design of Wood, CAN/CSA-O86.09 specifies expressions for the effects of short-term bending deflection on the PWF timber stud walls. PWF is subjected to gravity loads associated with lateral soil pressure. To use the available combined bending and axial compression equation for PWF design, it was observed that the soil pressure would cause short-term and long-term flexural creep deflection of the wall that would decrease the wall capacity. Information on the long-term creep behaviour of SIPs under sustained triangular loading, simulating soil pressure, is as yet unavailable. As such, this paper presents a summary of flexural creep tests conducted to determine the increase in SIP deflection under soil pressure over a period of eight months. Using the experimental data, the available mathematical and mechanical creep models were evaluated to predict the flexural creep constant (K) of SIP foundation wall subjected to soil pressure over a service life up to 75 years. A flexural creep constant was then proposed to determine the longterm eccentricity of gravity loading in the available combined bending and axial compression equation for PWF design.

The structural insulated panel (SIP) is an engineered composite product composed of an insulating... more The structural insulated panel (SIP) is an engineered composite product composed of an insulating foam core sandwiched to provide the insulation and rigidity, and two face-skin materials to provide durability and strength. SIPs can also be used as permanent wood foundation (PWF) for basements in low-rise residential construction to save in the energy cost. The maximum deflection equation specified in the Canadian Standard for Engineering Design of Wood, CAN/CSA-O86.09 specifies expressions for the effects of short-term bending deflection on the PWF timber stud walls. Information on the long-term creep behavior of SIPs under sustained triangular loading, simulating soil pressure, including effect of the change in ambient temperature and relative humidity is as yet unavailable. The long-term creep deflection for permanent wood foundation panels that is characterized as viscoelastic materials is highly affected by the change in ambient temperature and relative humidity. This paper reported the results from flexural creep experiments performed on two sets of different sizes of PWF made of structural-insulated foam-timber panels. In these tests, deflection, temperature and relative humidity were tracked for an eight-month period. The experimental findings were examined against existing creep models in the literature. Then, a creep model incorporating the effects of temperature and relative humidity on creep deflection was developed. Correlation between the proposed model and the experimental findings provides confidence on using the proposed model in the determination of the capacity of the PWF under combined gravity loading and sustained soil pressure as affected by temperature variation and relative humidity.

Proceedings of the International Conference on Civil, Structural and Transportation Engineering, Nov 1, 2020

The use of prefabricated elements and systems in bridge replacement (ABR) has recently been the s... more The use of prefabricated elements and systems in bridge replacement (ABR) has recently been the subject of much attention and interest amongst bridge jurisdictions in North America as a way of improving bridge construction and replacement of deteriorated bridges. Through mass production of the materials, the repeated use of forms, reduction of onsite construction time and labor by concentrating the construction effort in a fabrication facility rather than at the bridge site, significant economic benefits can be achieved. Issues related to work zone safety and traffic disruptions are also a major concern. A full-lane closure is very costly in busy urban highways because of the significant economic impact on commercial and industrial activities. As a result, prefabricated bridge technology is seen as a potential solution to many of these issues. Prefabricated elements and systems can be quickly assembled and could reduce design efforts, reduce the impact on the environment in the vicinity of the site, and minimize the delays and lane closure time and inconvenience to the traveling public, saving time and tax payers' money. Even at a higher initial cost, the use of prefabricated systems on bridges subjected to a high volume of traffic may be justified because excessive lane closure times can be avoided. This lecture presents the current state-of-the-art approach to the use of innovative prefabricated systems and elements in modern bridge construction. A summary of most recent ABR Guidelines and Specifications in Canada and USA will be covered. Also, the presentation will cover a variety of precast concrete girders, full-depth deck panels, abutment, piers and pile caps used to accelerate bridge construction. Moreover, a few of the latest precast connection details that have been implemented in Canada and USA using ultra-high performance fibre-reinforced concrete (UHPFRC) as connection filling material and non-corrosive glass fibre reinforced polymer (GFRP) bars as deck slab reinforcement will be covered. The use of stainless steel in replacing steel girders will be covered.

Elsevier eBooks, 2002

Publisher Summary A critical design stage for curved composite concrete deck-steel box girder bri... more Publisher Summary A critical design stage for curved composite concrete deck-steel box girder bridges occurs during casting the concrete bridge deck, when the non-composite steel box section must support the wet concrete and the entire construction loading. Although a composite box girder has a high torsional stiffness in the completed bridge, the open section during construction is relatively flexible in torsion. A horizontal truss system is usually installed at the top flange level to increase the torsional stiffness. Therefore, the aim of this chapter is to provide the practicing engineers with a better understanding of the structural behavior of such curved bridges under construction loading. This chapter presents a summary of an extensive parametric study, using the finite-element method, on which straight and curved single-cell steel bridges with different configurations are analyzed. The key parameters considered in the chapter include degree of curvature, vertical cross-bracing system, and top horizontal bracing system. This chapter focuses on the stresses and deflections at the mid-span section as well as support reactions. Since most current design methods neglect the effects of girder bending and torsional stresses on the horizontal and vertical bracings, the chapter gives particular attention to the horizontal forces in the top horizontal bracings as well as the vertical bracings due to pure bending or combined bending and torsion.

Proceedings of the International Conference on Civil, Structural and Transportation Engineering, Jun 1, 2022

This paper develops a simplified fiber-based numerical model to investigate the performance of ci... more This paper develops a simplified fiber-based numerical model to investigate the performance of circular concrete-filled stainless steel tubular (CFSST) short columns subjected to axial loading. A new compressive concrete strength formula is developed based on the test data of CFSST columns. The accuracy of the numerical model is evaluated by comparing the ultimate axial capacity and axial load-strain curves of CFSST columns with a large test database. A parametric study is carried out to investigate the effects of geometry and material properties on the axial performance of CFSST columns.

Construction and Building Materials, 2023

World Academy of Science, Engineering and Technology, International Journal of Civil, Environmental, Structural, Construction and Architectural Engineering, Mar 12, 2014

Engineering Structures, Sep 1, 2022

Advances in Structural Engineering, Dec 16, 2019

Due to its structural efficiency, durability, and cost-effectiveness, ultra-high performance conc... more Due to its structural efficiency, durability, and cost-effectiveness, ultra-high performance concrete was utilized to build the first highway overpass bridge in China. The bridge was made of prestressed ultra-high performance concrete box girders of four continuous spans of 30 m each. As the original design of such bridge was observed to be somewhat conservative, its cross-sectional dimensions, in the form of the box girder wall thicknesses were optimized in this research to lower the material cost in future bridge construction. Then, a full-scale simply supported ultra-high performance concrete box girder of 30 m span, incorporating the new box girder wall thicknesses, was fabricated and then tested under static loading to obtain research data to justify the revised design. The loading system was designed to examine the flexural behavior of the girder using two concentrated loads symmetrically located at the mid-span. Experimental results show that the optimized girder has a favorable ductile behavior and excellent flexural strength, which can meet the design requirements for serviceability and ultimate limit states. A finite element model of the tested girder was developed, using ABAQUS software, and then was verified using the experimental findings. A parametric study was then conducted to investigate the influence of key parameters on the structural response, namely, the reinforcement ratio, the number of the prestressing wires, and the web thickness. Recommendations on minimum and maximum compressive strength and tensile property of ultra-high performance concrete were proposed. Also, a simplified calculation method of prestressed ultra-high performance concrete box girder was developed based on a verified strain and stress diagrams for cross-sectional analysis. The proposed methodology can be used in future practice with confidence.

Materials and Structures, Jul 29, 2023

High-modulus (HM) ribbed-surface glass fiber reinforced polymer (GFRP) bars have recently been us... more High-modulus (HM) ribbed-surface glass fiber reinforced polymer (GFRP) bars have recently been used in concrete bridge decks to avoid corrosion of steel reinforcement resulting from the use of de-icing salts in winter times in North America. Recently, prefabricated full-depth deck panels (FDDPs), made of normal strength concrete or high performance concrete and reinforced with GFRP bars, are used in Canada to acceleration bridge construction. The FDDPs are connected through panel-to-panel and panel-to-girder connections. These connections are filled with joint-filled cementitious materials as ultra-high performance fiber-reinforced concrete (UHPFRC). This paper presents the experimental program to investigate the bond strength of the GFRP bars embedded into unconfined UHPFRC using pull-out testing, leading to the proper GFRP bar development length required to determine the width of the closure strip between connected slabs. The longitudinal GFRP/UHPFRC interface is influenced by (i) the development length-to-nominal diameter of the bar ratio, (ii) the concrete cover-to-bar diameter ratio and (iii) the development length-to-embedment depth ratio due to lugs or headed-end and (iv) concrete compressive strength. GFRP bars embedded into UHPFRC would rely less on the friction and adhesion of the interface, and more on the bearing of the lugs against the concrete. These bearing forces act at an angle to the axis of the bar, causing radial outward forces. Pullout failure of the GFRP/UHPFRC interface leads to shearing of the lugs and bar slippage from the headed-end. Adequate bond strength between the GFRP/UHPFRC interfaces is necessary for design of jointed PDDFs. Therefore, accurate predictions of development length and bond strength of straight or headed-end bars without passing through the high localized stresses due to flexural are essential for safe design.

Proceedings of the 2nd World Congress on Civil, Structural, and Environmental Engineering, Mar 1, 2023

The Canadian Highway Bridge Design Code, CHBDC, is based on limit states design principles and de... more The Canadian Highway Bridge Design Code, CHBDC, is based on limit states design principles and defines design loadings, load combinations and load factors, and detailed design criteria for the various materials and bridge types. CHBDC specifies simplified method of analysis of slab-on-girder bridges in lieu of conducting detailed refined analysis of the bridge structure. The 2019 version of CHBDC addressed the need for simplified method of analysis for prefabricated bridge systems for use in accelerated bridge construction and replacement. These bridges include the following shear-connected adjacent precast beam types: box beams, voided slab units, T-beams, Double-T beams, and Inverted-U beams. A summary of an experimental work on developed joint details between adjacent beams will be presented and compared to the specified transverse factored applied vertical shear force between shear-connected beams for shear key design. A method for the design of deck slab cantilever overhang due to (i) truck loading conditions and (ii) vehicle collision loads applied to concrete barriers mounted integrally with the deck overhang. A design methodology for a concrete section subjected to combined bending moment and axial force will be presented. Finally, a new simplified method of analysis is provided for determining the factored flexural resistance of steel-reinforced concrete barrier to transverse traffic barrier load based on a trapezoidal yieldline failure pattern.

Advances in Structural Engineering

A square concrete-filled double steel tubular (CFDST) column composed of a circular core concrete... more A square concrete-filled double steel tubular (CFDST) column composed of a circular core concrete-filled tube offers the advantages of both square and circular concrete-filled steel tubular (CFST) columns. However, limited tests were performed to investigate the axial performance of CFDST slender columns. This paper investigates the behavior and design of square CFDST slender columns subjected to concentric loading. A total of eight columns, including six CFDST slender columns and two CFDST short columns were tested under concentric loading. The test parameter includes the slenderness ratio of the columns and the thickness of the inner tube. The ultimate load, failure modes and axial load-deflection relationships of CFDST slender columns are presented. It was observed that square CFDST slender columns failed due to the overall buckling of the columns together with the localized buckling of the steel tube and concrete crushing. Increasing the slenderness ratio and decreasing the thic...