Patrick Heffernan - Academia.edu (original) (raw)
Papers by Patrick Heffernan
Proceedings of the Canadian Engineering Education Association, 2011
At RMC, in Mechanical Engineering, the third-year course MEE 303 ‘Principles of Engineering Desig... more At RMC, in Mechanical Engineering, the third-year course MEE 303 ‘Principles of Engineering Design’ consists of 12 lectures and two mini-projects, one for redesign, and one for novel design. The redesign alternates between a water valve and an automotive oil pump. This case study is now up-to-date according to the most recent developments in the theoretical framework that is the basis for the systematic and methodical process. The search for solutions in this process involves creativity supported by systematic working.An automotive oil pump is to be redesigned for revised conditions. The existing oil pump originated from the 1970’s, and was used in a V-8 engine. A reconstituted set of engineering drawing was prepared. Using the recommended systematic procedure, and other appropriate methods, students were asked to perform the redesign process: to develop a design specification, to analyze the existing pump to detect organs and functions, to explore the solution field with a morpholo...
Structures Under Shock and Impact XI, 2010
Blast load parameters are reasonably easily determined for rectangular columns and can be derived... more Blast load parameters are reasonably easily determined for rectangular columns and can be derived from either the literature or numerous utility programs. Little compiled information is available with respect to exposed round columns. A series of numerical simulations were carried out to investigate the design pressure imparted to a round column by an explosion. The column diameter and charge weight were varied and pressure-time histories recorded at regular radial intervals along the face of the column from the closest point of first contact (front) to the extreme point at the side. A numerical model was created in AUTODYN, which simulated a blast wave diffracting around a rigid round cross section. The results indicate that as the diameter of the section increases, the peak reflected pressure at the point of first contact rapidly approaches that of a flat wall. However, the pressure varies sinusoidally between this peak at the point of first contact to a minimum equal to approximately the incident pressure at the furthest point at the side. The results support the obvious advantages when designing against blast to be realized by the use of round vs. rectangular columns, particularly when in the near field.
ACI Structural Journal, 2004
Proceedings of the Canadian Engineering Education Association, 2011
Journal of Structural Engineering, 2016
AbstractA major difficulty of the analysis of and design for close-in blasts is the high variabil... more AbstractA major difficulty of the analysis of and design for close-in blasts is the high variability of the blast shock waves and the complex interactions between these waves and structures. Close-in blasts also tend to be severe loads that may cause extensive damage to a structural member. If the member in question is a load bearing column, its destruction may lead to a catastrophic progressive collapse of the structure. Thus any improvement on the performance of columns under close-in blast loading is a valuable addition to knowledge. This paper outlines a numerical model built using commercially available software to predict the response of concrete filled fiber reinforced polymer (FRP) tubes (CFFTs) and regular round reinforced concrete members to impacts and close-in blasts and determine the factors influencing their response. The models were verified against drop weight impact test lab measurements and single degree of freedom blast analyses. A parametric study was conducted using the verified model...
Engineering Structures, 2015
ABSTRACT Numerous experimental investigations have demonstrated the advantages of Concrete Filled... more ABSTRACT Numerous experimental investigations have demonstrated the advantages of Concrete Filled FRP Tubes (CFFTs) over reinforced concrete members under various loading conditions. None of the studies, however, investigated whether these advantages of CFFTs extended to resisting dynamic impact loads. This presented a fertile field for investigation as it was well known that the addition of the tube confined and protected the concrete core and increased its load carrying capacity, and by extension, its energy absorption. This investigation aimed at understanding the dynamic behaviour of CFFTs under impact loading and to develop a procedure for their analysis and design. These aims were achieved by testing six specimens, three of which were CFFTs and three were reinforced concrete. The specimens were tested in pairs to facilitate comparisons. The first pair were tested monotonically to act as a benchmark and tie into previous research. The remaining two pairs were tested under impact loading. The parameters investigated were the presence of the GFRP tube, the internal steel reinforcement ratio, and the input kinetic energy. The monotonic tests showed that the addition of the tube increased the flexural capacity and maximum displacement by 112%, which translated into a 487.5% increase in energy absorption, when compared to the reinforced concrete counterpart. The addition of the tube increased the impact specimens’ energy absorbing capacity by 467% when the steel reinforcement ratio was 1.2% and 1223% when the steel reinforcement ratio was 2.4%, compared to the reinforced concrete specimens. The GFRP tube also protected the concrete core and prevented its spalling and crushing during the impact tests. These encouraging experimental results led to the development of a nonlinear single degree of freedom (SDOF) model capable of capturing the behaviour of the system under multiple impacts to be used as a sophisticated analysis and design tool. Additionally, a simplified design method based on the conservation of energy was outlined.
International Journal of Protective Structures, 2015
A number of experimenters observed that the blast shockwave loads experienced by circular cross s... more A number of experimenters observed that the blast shockwave loads experienced by circular cross sections were lower than the predicted loads. These observations revealed a gap in the understanding of the interaction between blasts and structures. The question of quantifying these reduced loads for purposes of analysis and design presented itself for investigation. This paper presents the numerical investigation of the blast reflection reduction due to diffraction around a circular cross section using the commercial software ANSYS Autodyn. The investigation focused on the effects of the cross section's diameter and the explosion's scaled distance on the reflected blast pressure and impulse. Nine numerical gauge points recorded pressure-time and impulse-time histories at regular radial intervals around the front quarter of the circular section. The model's results agreed with incident and reflected pressure and impulse design values. The results indicated that as the diameter of the section increased the peak reflected pressure and impulse at the point of incidence rapidly approached the design values. The results also indicated that both the pressure and the impulse varied sinusoidally between a maximum at the point of incidence and a minimum, approximately equal to the incident pressure and impulse, at the side of the section. Using a sinusoidal curve fit to obtain equivalent reflected pressure and impulse values showed that the actual pressure and impulse acting on a circular cross section were approximately half the recommended design values. The results supported the obvious advantages of designing circular members to resist blast loading. Simplified equations are proposed for calculating the equivalent pressure and impulse acting on circular sections from the standard design values.
Journal of Composites for Construction, 2015
AbstractBlasts, whether deliberate or accidental, are a great concern for a society’s critical in... more AbstractBlasts, whether deliberate or accidental, are a great concern for a society’s critical infrastructure as well as expeditionary military installations. Improvement to existing construction methods that enhance blast resilience can ultimately save lives and property. Concrete-filled FRP tubes (CFFTs) are known to improve a conventional reinforced concrete member’s resistance to traditional loads by strengthening, protecting, and confining the reinforced concrete core. Glass fibre reinforced polymer (GFRP) tubes are readily available in a variety of sizes suitable for use as a stay-in-place structural formwork for midsized reinforced concrete members, which can simplify and expedite construction. These advantages point to CFFTs’ great potential in resisting blast loads. This study aimed to quantify the advantages of encasing a reinforced concrete member with a GFRP tube subjected to close-in blast loading and to investigate the effects of the presence of the tube, the internal steel reinforcement rat...
Fibre-Reinforced Polymer Reinforcement for Concrete Structures, 2003
Structural Engineering International, 2002
ABSTRACT Complementary to the work of ISIS Canada, several Canadian Federal Government department... more ABSTRACT Complementary to the work of ISIS Canada, several Canadian Federal Government departments and agencies are studying and implementing FRP solutions to structural challenges. The focus of this work is on the effectiveness of FRP for strengthening severely damaged structures or structures subjected to blast, seismic loading or fire exposure.
Journal of Materials in Civil Engineering, 2009
Journal of Composites for Construction, 2004
ABSTRACT Although there has been growing interest and field applications of poststrengthening con... more ABSTRACT Although there has been growing interest and field applications of poststrengthening concrete structures using carbon fiber reinforced plastic (CFRP) laminates, very little information exists regarding the flexural fatigue behavior of reinforced concrete beams strengthened with CFRP. This paper presents the results of an investigation into the fatigue behavior of reinforced concrete beams poststrengthened with CFRP laminates. The results of twenty 3 m and six 5 m beams loaded monotonically and cyclically to failure are discussed. Comparisons are made between beams without and with CFRP strengthening. The effect on fatigue life of increasing the amount of CFRP used to strengthen the beams is also examined.
Journal of Composites for Construction, 2008
ABSTRACT This paper presents the recent progress and achievement in the application of fiber-rein... more ABSTRACT This paper presents the recent progress and achievement in the application of fiber-reinforced polymers (FRP) on strengthening reinforced/prestressed concrete beams subjected to fatigue loading. Although the performance of FRP-strengthened structures under monotonic loading has been intensively investigated, fatigue behavior is relatively less known to date. This paper summarizes most of the currently available literature, including the codes and design manuals, on reinforced/prestressed concrete beams externally strengthened with FRP. The review focuses specifically on the fatigue life as a function of the applied load range, bond behavior of externally bonded FRP, damage accumulation, crack propagation, size effects, residual strength, and failure modes. Research needs including considerations for design guidelines are presented.
Journal of Bridge Engineering, 2006
For military and civilian applications, there exists a need for lightweight, inexpensive, short-s... more For military and civilian applications, there exists a need for lightweight, inexpensive, short-span bridges that can be easily transported and erected with minimal equipment. Owing to its favorable properties, fiber-reinforced polymer (FRP) has been shown to be feasible for the construction of such bridges. Investigations into the behavior of a short-span bridge structural concept, adapted to the material properties of commercially available glass FRP (GFRP) pultruded products, are presented. A 4.8-m span prototype was built from GFRP sections, bonded throughout to form a tapered box beam, with a width of 1.2 m and a height at midspan of approximately 0.5 m. The box beam represents a single trackway of a double-trackway bridge, whose trackways could be connected by light structural elements. The quasi-static and dynamic behavior of the prototype box beam was investigated in ambient laboratory and field conditions to assess the design and construction techniques used, with a view to designing a full-scale 10-m GFRP bridge. Laboratory testing of the prototype box beam used single and pairs of patch loads to simulate wheel loading. These tests confirmed that the box beam had sufficient stiffness and strength to function effectively as a single trackway of a small span bridge. Field testing of the structure was undertaken using a Bison vehicle (13,000 kg), driven at varying speeds over the structure to establish its response to realistic vehicle loads and the effects of their movement across the span.
Canadian Journal of Civil Engineering, 2009
During the past decade, significant research has been carried out on the strengthening of reinfor... more During the past decade, significant research has been carried out on the strengthening of reinforced concrete (RC) slabs, beams, and columns using externally bonded carbon fibre reinforced polymer (CFRP) sheets. Steel reinforced polymer (SRP) sheets have recently been proposed as an alternative to CFRP to strengthen reinforced concrete beams. This paper reports experimental and numerical results of RC beams and beam-columns transversely wrapped with SRP and tested under blast load. A total of 10 scaled RC members were tested at a variety of blast wave intensities. Detailed observations are reported and validated against numerical models created in AUTODYN for the unstrengthened RC members. The SRP wraps were resilient in the near-field blast range and enhanced the ductility of the concrete likely through enhanced confinement. Member capacity could be increased by the wraps in failure modes dominated by concrete crushing. AUTODYN appears able to reasonably predict the behaviour of th...
WIT Transactions on State of the Art in Science and Engineering, 2012
Journal of Composites for Construction, 2011
ABSTRACT Research into the use of fiber-reinforced polymers (FRPs) in structures at the Royal Mil... more ABSTRACT Research into the use of fiber-reinforced polymers (FRPs) in structures at the Royal Military College of Canada (RMC) during the past two decades has largely focused on two important military engineering goals-mobility and survivability. FRP research in the area of mobility has included the strengthening and repair of reinforced concrete beams and slabs and the development of portable lightweight bridges suitable for most wheeled and tracked vehicles. With respect to survivability, a particular interest is in the use of FRPs to enhance the blast resistance of structural columns and beams. Such research may be equally pertinent to improving the blast resistance of a broad range of critical domestic infrastructure worldwide, given both the increasing concerns about terrorist acts and the desire as well to improve resistance to accidental explosion. This paper will report on the experimental work of two of the most recent FRP research projects carried out at the RMC in support of military objectives-the development of a lightweight portable glass FRP bridge and the use of FRP to strengthen reinforced concrete structural columns against blast. A full-sized FRP box beam was constructed and tested in the laboratory and 28 half-scale reinforced concrete columns, some strengthened with either steel reinforced polymer (SRP) or with FRP, were tested in the field under blast load. From this research, it can be seen that FRP as a structural material offers significant advantages to military forces working in conflict zones, whether for traditional strengthening of damaged or understrength structures, lightweight portable bridge options, or as a means of strengthening structures against blast effects. DOI: 10.1061/(ASCE)CC.1943-5614.0000077. (C) 2011 American Society of Civil Engineers.
International Journal of Fatigue, 2007
The corrosion-fatigue behaviour of 7075-T651 aluminum alloy subjected to periodic overloads was e... more The corrosion-fatigue behaviour of 7075-T651 aluminum alloy subjected to periodic overloads was examined. This aluminum alloy is typically used in aerospace structural components such as the wing spars of aircraft. Axial fatigue specimens were subjected to a loading spectrum that consisted of a fully reversed periodic overload of near-yield magnitude followed by 200 smaller cycles at high Rratio. The specimens were fatigue tested while they were fully immersed in an aerated and recirculated 3.5 wt% NaCl simulated seawater solution. The results for the corrosion-fatigue testing were compared to data obtained for the same overload spectrum applied in laboratory air. A damage analysis showed that the presence of the corrosive environment accelerated the damage accumulation rate to a greater extent than that observed in air, particularly at low stress ranges. This resulted in a reduction in the fatigue strength of the material when it was simultaneously subjected to overloads and a corrosive environment. It is believed that the reduced fatigue life was due primarily to corrosion pit formation and a combination of anodic dissolution at the crack tip and hydrogen embrittlement. For practical purposes, the endurance-limit of the material disappears under these conditions.
Journal of Materials in …, 2009
Most of the previous research on the fatigue of reinforcing bars has been based on constant ampli... more Most of the previous research on the fatigue of reinforcing bars has been based on constant amplitude fatigue tests performed in a noncorrosive environment. Fatigue in a corrosive environment, known as corrosion fatigue, can result in a synergistic damage mechanism ...
Proceedings of the Canadian Engineering Education Association, 2011
At RMC, in Mechanical Engineering, the third-year course MEE 303 ‘Principles of Engineering Desig... more At RMC, in Mechanical Engineering, the third-year course MEE 303 ‘Principles of Engineering Design’ consists of 12 lectures and two mini-projects, one for redesign, and one for novel design. The redesign alternates between a water valve and an automotive oil pump. This case study is now up-to-date according to the most recent developments in the theoretical framework that is the basis for the systematic and methodical process. The search for solutions in this process involves creativity supported by systematic working.An automotive oil pump is to be redesigned for revised conditions. The existing oil pump originated from the 1970’s, and was used in a V-8 engine. A reconstituted set of engineering drawing was prepared. Using the recommended systematic procedure, and other appropriate methods, students were asked to perform the redesign process: to develop a design specification, to analyze the existing pump to detect organs and functions, to explore the solution field with a morpholo...
Structures Under Shock and Impact XI, 2010
Blast load parameters are reasonably easily determined for rectangular columns and can be derived... more Blast load parameters are reasonably easily determined for rectangular columns and can be derived from either the literature or numerous utility programs. Little compiled information is available with respect to exposed round columns. A series of numerical simulations were carried out to investigate the design pressure imparted to a round column by an explosion. The column diameter and charge weight were varied and pressure-time histories recorded at regular radial intervals along the face of the column from the closest point of first contact (front) to the extreme point at the side. A numerical model was created in AUTODYN, which simulated a blast wave diffracting around a rigid round cross section. The results indicate that as the diameter of the section increases, the peak reflected pressure at the point of first contact rapidly approaches that of a flat wall. However, the pressure varies sinusoidally between this peak at the point of first contact to a minimum equal to approximately the incident pressure at the furthest point at the side. The results support the obvious advantages when designing against blast to be realized by the use of round vs. rectangular columns, particularly when in the near field.
ACI Structural Journal, 2004
Proceedings of the Canadian Engineering Education Association, 2011
Journal of Structural Engineering, 2016
AbstractA major difficulty of the analysis of and design for close-in blasts is the high variabil... more AbstractA major difficulty of the analysis of and design for close-in blasts is the high variability of the blast shock waves and the complex interactions between these waves and structures. Close-in blasts also tend to be severe loads that may cause extensive damage to a structural member. If the member in question is a load bearing column, its destruction may lead to a catastrophic progressive collapse of the structure. Thus any improvement on the performance of columns under close-in blast loading is a valuable addition to knowledge. This paper outlines a numerical model built using commercially available software to predict the response of concrete filled fiber reinforced polymer (FRP) tubes (CFFTs) and regular round reinforced concrete members to impacts and close-in blasts and determine the factors influencing their response. The models were verified against drop weight impact test lab measurements and single degree of freedom blast analyses. A parametric study was conducted using the verified model...
Engineering Structures, 2015
ABSTRACT Numerous experimental investigations have demonstrated the advantages of Concrete Filled... more ABSTRACT Numerous experimental investigations have demonstrated the advantages of Concrete Filled FRP Tubes (CFFTs) over reinforced concrete members under various loading conditions. None of the studies, however, investigated whether these advantages of CFFTs extended to resisting dynamic impact loads. This presented a fertile field for investigation as it was well known that the addition of the tube confined and protected the concrete core and increased its load carrying capacity, and by extension, its energy absorption. This investigation aimed at understanding the dynamic behaviour of CFFTs under impact loading and to develop a procedure for their analysis and design. These aims were achieved by testing six specimens, three of which were CFFTs and three were reinforced concrete. The specimens were tested in pairs to facilitate comparisons. The first pair were tested monotonically to act as a benchmark and tie into previous research. The remaining two pairs were tested under impact loading. The parameters investigated were the presence of the GFRP tube, the internal steel reinforcement ratio, and the input kinetic energy. The monotonic tests showed that the addition of the tube increased the flexural capacity and maximum displacement by 112%, which translated into a 487.5% increase in energy absorption, when compared to the reinforced concrete counterpart. The addition of the tube increased the impact specimens’ energy absorbing capacity by 467% when the steel reinforcement ratio was 1.2% and 1223% when the steel reinforcement ratio was 2.4%, compared to the reinforced concrete specimens. The GFRP tube also protected the concrete core and prevented its spalling and crushing during the impact tests. These encouraging experimental results led to the development of a nonlinear single degree of freedom (SDOF) model capable of capturing the behaviour of the system under multiple impacts to be used as a sophisticated analysis and design tool. Additionally, a simplified design method based on the conservation of energy was outlined.
International Journal of Protective Structures, 2015
A number of experimenters observed that the blast shockwave loads experienced by circular cross s... more A number of experimenters observed that the blast shockwave loads experienced by circular cross sections were lower than the predicted loads. These observations revealed a gap in the understanding of the interaction between blasts and structures. The question of quantifying these reduced loads for purposes of analysis and design presented itself for investigation. This paper presents the numerical investigation of the blast reflection reduction due to diffraction around a circular cross section using the commercial software ANSYS Autodyn. The investigation focused on the effects of the cross section's diameter and the explosion's scaled distance on the reflected blast pressure and impulse. Nine numerical gauge points recorded pressure-time and impulse-time histories at regular radial intervals around the front quarter of the circular section. The model's results agreed with incident and reflected pressure and impulse design values. The results indicated that as the diameter of the section increased the peak reflected pressure and impulse at the point of incidence rapidly approached the design values. The results also indicated that both the pressure and the impulse varied sinusoidally between a maximum at the point of incidence and a minimum, approximately equal to the incident pressure and impulse, at the side of the section. Using a sinusoidal curve fit to obtain equivalent reflected pressure and impulse values showed that the actual pressure and impulse acting on a circular cross section were approximately half the recommended design values. The results supported the obvious advantages of designing circular members to resist blast loading. Simplified equations are proposed for calculating the equivalent pressure and impulse acting on circular sections from the standard design values.
Journal of Composites for Construction, 2015
AbstractBlasts, whether deliberate or accidental, are a great concern for a society’s critical in... more AbstractBlasts, whether deliberate or accidental, are a great concern for a society’s critical infrastructure as well as expeditionary military installations. Improvement to existing construction methods that enhance blast resilience can ultimately save lives and property. Concrete-filled FRP tubes (CFFTs) are known to improve a conventional reinforced concrete member’s resistance to traditional loads by strengthening, protecting, and confining the reinforced concrete core. Glass fibre reinforced polymer (GFRP) tubes are readily available in a variety of sizes suitable for use as a stay-in-place structural formwork for midsized reinforced concrete members, which can simplify and expedite construction. These advantages point to CFFTs’ great potential in resisting blast loads. This study aimed to quantify the advantages of encasing a reinforced concrete member with a GFRP tube subjected to close-in blast loading and to investigate the effects of the presence of the tube, the internal steel reinforcement rat...
Fibre-Reinforced Polymer Reinforcement for Concrete Structures, 2003
Structural Engineering International, 2002
ABSTRACT Complementary to the work of ISIS Canada, several Canadian Federal Government department... more ABSTRACT Complementary to the work of ISIS Canada, several Canadian Federal Government departments and agencies are studying and implementing FRP solutions to structural challenges. The focus of this work is on the effectiveness of FRP for strengthening severely damaged structures or structures subjected to blast, seismic loading or fire exposure.
Journal of Materials in Civil Engineering, 2009
Journal of Composites for Construction, 2004
ABSTRACT Although there has been growing interest and field applications of poststrengthening con... more ABSTRACT Although there has been growing interest and field applications of poststrengthening concrete structures using carbon fiber reinforced plastic (CFRP) laminates, very little information exists regarding the flexural fatigue behavior of reinforced concrete beams strengthened with CFRP. This paper presents the results of an investigation into the fatigue behavior of reinforced concrete beams poststrengthened with CFRP laminates. The results of twenty 3 m and six 5 m beams loaded monotonically and cyclically to failure are discussed. Comparisons are made between beams without and with CFRP strengthening. The effect on fatigue life of increasing the amount of CFRP used to strengthen the beams is also examined.
Journal of Composites for Construction, 2008
ABSTRACT This paper presents the recent progress and achievement in the application of fiber-rein... more ABSTRACT This paper presents the recent progress and achievement in the application of fiber-reinforced polymers (FRP) on strengthening reinforced/prestressed concrete beams subjected to fatigue loading. Although the performance of FRP-strengthened structures under monotonic loading has been intensively investigated, fatigue behavior is relatively less known to date. This paper summarizes most of the currently available literature, including the codes and design manuals, on reinforced/prestressed concrete beams externally strengthened with FRP. The review focuses specifically on the fatigue life as a function of the applied load range, bond behavior of externally bonded FRP, damage accumulation, crack propagation, size effects, residual strength, and failure modes. Research needs including considerations for design guidelines are presented.
Journal of Bridge Engineering, 2006
For military and civilian applications, there exists a need for lightweight, inexpensive, short-s... more For military and civilian applications, there exists a need for lightweight, inexpensive, short-span bridges that can be easily transported and erected with minimal equipment. Owing to its favorable properties, fiber-reinforced polymer (FRP) has been shown to be feasible for the construction of such bridges. Investigations into the behavior of a short-span bridge structural concept, adapted to the material properties of commercially available glass FRP (GFRP) pultruded products, are presented. A 4.8-m span prototype was built from GFRP sections, bonded throughout to form a tapered box beam, with a width of 1.2 m and a height at midspan of approximately 0.5 m. The box beam represents a single trackway of a double-trackway bridge, whose trackways could be connected by light structural elements. The quasi-static and dynamic behavior of the prototype box beam was investigated in ambient laboratory and field conditions to assess the design and construction techniques used, with a view to designing a full-scale 10-m GFRP bridge. Laboratory testing of the prototype box beam used single and pairs of patch loads to simulate wheel loading. These tests confirmed that the box beam had sufficient stiffness and strength to function effectively as a single trackway of a small span bridge. Field testing of the structure was undertaken using a Bison vehicle (13,000 kg), driven at varying speeds over the structure to establish its response to realistic vehicle loads and the effects of their movement across the span.
Canadian Journal of Civil Engineering, 2009
During the past decade, significant research has been carried out on the strengthening of reinfor... more During the past decade, significant research has been carried out on the strengthening of reinforced concrete (RC) slabs, beams, and columns using externally bonded carbon fibre reinforced polymer (CFRP) sheets. Steel reinforced polymer (SRP) sheets have recently been proposed as an alternative to CFRP to strengthen reinforced concrete beams. This paper reports experimental and numerical results of RC beams and beam-columns transversely wrapped with SRP and tested under blast load. A total of 10 scaled RC members were tested at a variety of blast wave intensities. Detailed observations are reported and validated against numerical models created in AUTODYN for the unstrengthened RC members. The SRP wraps were resilient in the near-field blast range and enhanced the ductility of the concrete likely through enhanced confinement. Member capacity could be increased by the wraps in failure modes dominated by concrete crushing. AUTODYN appears able to reasonably predict the behaviour of th...
WIT Transactions on State of the Art in Science and Engineering, 2012
Journal of Composites for Construction, 2011
ABSTRACT Research into the use of fiber-reinforced polymers (FRPs) in structures at the Royal Mil... more ABSTRACT Research into the use of fiber-reinforced polymers (FRPs) in structures at the Royal Military College of Canada (RMC) during the past two decades has largely focused on two important military engineering goals-mobility and survivability. FRP research in the area of mobility has included the strengthening and repair of reinforced concrete beams and slabs and the development of portable lightweight bridges suitable for most wheeled and tracked vehicles. With respect to survivability, a particular interest is in the use of FRPs to enhance the blast resistance of structural columns and beams. Such research may be equally pertinent to improving the blast resistance of a broad range of critical domestic infrastructure worldwide, given both the increasing concerns about terrorist acts and the desire as well to improve resistance to accidental explosion. This paper will report on the experimental work of two of the most recent FRP research projects carried out at the RMC in support of military objectives-the development of a lightweight portable glass FRP bridge and the use of FRP to strengthen reinforced concrete structural columns against blast. A full-sized FRP box beam was constructed and tested in the laboratory and 28 half-scale reinforced concrete columns, some strengthened with either steel reinforced polymer (SRP) or with FRP, were tested in the field under blast load. From this research, it can be seen that FRP as a structural material offers significant advantages to military forces working in conflict zones, whether for traditional strengthening of damaged or understrength structures, lightweight portable bridge options, or as a means of strengthening structures against blast effects. DOI: 10.1061/(ASCE)CC.1943-5614.0000077. (C) 2011 American Society of Civil Engineers.
International Journal of Fatigue, 2007
The corrosion-fatigue behaviour of 7075-T651 aluminum alloy subjected to periodic overloads was e... more The corrosion-fatigue behaviour of 7075-T651 aluminum alloy subjected to periodic overloads was examined. This aluminum alloy is typically used in aerospace structural components such as the wing spars of aircraft. Axial fatigue specimens were subjected to a loading spectrum that consisted of a fully reversed periodic overload of near-yield magnitude followed by 200 smaller cycles at high Rratio. The specimens were fatigue tested while they were fully immersed in an aerated and recirculated 3.5 wt% NaCl simulated seawater solution. The results for the corrosion-fatigue testing were compared to data obtained for the same overload spectrum applied in laboratory air. A damage analysis showed that the presence of the corrosive environment accelerated the damage accumulation rate to a greater extent than that observed in air, particularly at low stress ranges. This resulted in a reduction in the fatigue strength of the material when it was simultaneously subjected to overloads and a corrosive environment. It is believed that the reduced fatigue life was due primarily to corrosion pit formation and a combination of anodic dissolution at the crack tip and hydrogen embrittlement. For practical purposes, the endurance-limit of the material disappears under these conditions.
Journal of Materials in …, 2009
Most of the previous research on the fatigue of reinforcing bars has been based on constant ampli... more Most of the previous research on the fatigue of reinforcing bars has been based on constant amplitude fatigue tests performed in a noncorrosive environment. Fatigue in a corrosive environment, known as corrosion fatigue, can result in a synergistic damage mechanism ...