- Rolla, Missouri, United States
- Structural Engineeredit
Water film depth (WFD) is an essential factor regarding road traffic safety on the roads due to its direct connection with skid resistance, hydroplaning speed, and the tendency of splash and spray. Increasing the pavement macrotexture is... more
Water film depth (WFD) is an essential factor regarding road traffic safety on the roads due to its direct connection with skid resistance, hydroplaning speed, and the tendency of splash and spray. Increasing the pavement macrotexture is one of the solutions to reduce the WFD. Therefore, chip seal can be a viable option for reducing the WFD. However, the existing models of WFD prediction are not developed based on highly textured surfaces like chip seal. Besides, the rainfall intensity ranges used for developing most of these models do not raise safety issues on chip seal surfaces. To propose a new WFD prediction model, an experimental study was conducted on 154 different combinations of texture depth, surface material type, surface slope, drainage length, and rainfall intensity using a full-scale rainfall simulator. To study the effects of surface material type and also evaluate the newly proposed eco-friendly rubberized chip seal, mineral aggregate and crumb rubber were used as aggregate. Test results through 1,784 WFD readings indicated that the well-known Gallaway and PAVDRN models are not accurate for chip seal surfaces. Hence, two new analytical models were proposed to predict the WFD, which showed a significantly higher correlation between the actual and the predicted WFD compared to the existing models. Besides, the rubberized chip seal performed an enhanced drainage capability compared to conventional chip seal, especially in low slopes, due to the hydrophobic nature of crumb rubber. Accordingly, the proposed model incorporated a term to consider the effect of surface material type
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Chip seals are one of the most cost and performance effective pavement preservation treatments commonly used in the United States. An eco-friendly chip seal pavement, in which the natural aggregate was replaced by crumb rubber obtained... more
Chip seals are one of the most cost and performance effective pavement preservation treatments commonly used in the United States. An eco-friendly chip seal pavement, in which the natural aggregate was replaced by crumb rubber obtained from scrap tires, was recently developed by the research team at Missouri S&T, creating rubberized chip seal. This project investigated and optimized the performance of rubberized chip seal under different scenarios. During this project, laboratory chip seal specimens with different sizes were prepared and tested under simulated traffic loads with different loading parameters and environmental conditions. Also, the feasibility of the implementation and performance of rubberized chip seal in the field was investigated in two different field sections. Test results indicated that a crumb rubber replacement ratio up to 50% is appropriate for low traffic roads with 0.25 gal/yd2 emulsion rate and aggregate with a low flakiness index. 100% rubberized chip seal also performed considerably better for high-speed traffic, snowplowing action, and high-temperature environments. Also, a highly reliable water film depth prediction model was proposed for conventional and rubberized chip seal. Field implementation projects indicated that using up to 50% rubberized chip seal could be successfully implemented in the field using conventional chip sealing procedures and equipment
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An experimental investigation of the shear behaviour of Ultra-high performance concrete (UHPC) beams with web openings was conducted. Eight UHPC beams were experimentally cast and subjected to a four-point bending test. One beam, which... more
An experimental investigation of the shear behaviour of Ultra-high performance concrete (UHPC) beams with web openings was conducted. Eight UHPC beams were experimentally cast and subjected to a four-point bending test. One beam, which was considered the control specimen, had no web openings, whereas the seven other beams contained openings. The studied parameters were steel fibre content, opening position, opening shape and reinforcement schemes around the web openings. Shear behaviour was evaluated on the basis of cracking patterns , load-deflection behaviour, ductility, initial stiffness, toughness and strain. Experimental results showed that increasing the volume fraction of steel fibres enhanced the shear strength, stiffness, toughness, ductility and strain in steel reinforcements. The presence of web openings in the shear region led to a decrease in the shear strength by 33.7%. The ultimate load of UHPC beams with openings has been evidently improved using reinforcement around the openings. An analytical verification was proposed to evaluate the experimental test results of UHPC beam by using design codes, different prediction equations and the empirical equation proposed herein. The proposed empirical equation showed an excellent agreement with available experimental data.
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I am grateful to Dr. Mohamed A. ElGawady, the chairman of my committee, for his patience and guidance through this project. I would also like to thank Dr. William Cofer and Dr. Balasingam Muhunthan for their participation and assistance... more
I am grateful to Dr. Mohamed A. ElGawady, the chairman of my committee, for his patience and guidance through this project. I would also like to thank Dr. William Cofer and Dr. Balasingam Muhunthan for their participation and assistance on my committee. A special thanks for Steve Greenwood who partnered with me on this project. I like to thank my family for supporting me throughout, specially my mom who always pushes me to be the best I can be. iii NONLINEAR DYNAMIC AND STATIC ANALYSIS OF I-5 RAVENNA BRIDGE
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Used for very tall bridge columns in seismic areas, including New Zealand, Japan and Italy, hollow-core concrete columns (HCCCs) utilize cross-sections to reduce the mass of the column, thus reducing the bridge self-weight, which... more
Used for very tall bridge columns in seismic areas, including New Zealand, Japan and Italy, hollow-core concrete columns (HCCCs) utilize cross-sections to reduce the mass of the column, thus reducing the bridge self-weight, which contributes to the inertial forces resulting from earthquakes. HCCCs also enable a reduction of the required foundation dimensions, which reduces construction costs substantially. In addition, HCCCs use less concrete than solid cross-section columns, making them more sustainable. The seismic behavior of various types of HCCCs has been investigated by researchers, as detailed in this article. Of particular interest is an innovative type of hollow-core bridge column consisting of a concrete wall that is sandwiched between an outer fiber-reinforced polymer (FRP) tube and an inner steel tube producing what is called hollow-core FRP-concrete-steel columns (HC-FCS). This column combines and optimizes the benefits of all three materials: FRP, concrete and steel.
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This study investigated the use of class C fly ash (FA) as a precursor for alkali-activated mortar (AAM) for 3D-printed concrete (3DPC). AAMs with different water-to-FA (W/FA), alkaline activator-to-FA (Alk/FA), and sodium... more
This study investigated the use of class C fly ash (FA) as a precursor for alkali-activated mortar (AAM) for 3D-printed concrete (3DPC). AAMs with different water-to-FA (W/FA), alkaline activator-to-FA (Alk/FA), and sodium silicate-to-sodium hydroxide (SS/SH) ratios were examined to develop mixtures that can be tailored for different structural applications of 3DPC. The fresh properties, including extrudability and buildability, were evaluated through the open time (OT) and immediate deformation tests, respectively. Different cycle times (CTs) were applied to achieve a strain limit state necessary to maintain the printed shape. The strength of AAMs in different directions at different CTs was examined. Scanning electron microscopy (SEM) was carried out on AAM specimens having different CTs for a better understanding of the bond area. OTs ranging from 2.5 min to 31 min and axial strains ranging from 0.17% to 11.2% were achieved depending on the proportions of the AAMs and CT, which o...
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Research Interests: Environmental Engineering, Materials Science, Cleaner Production, Adhesion, Manufacturing Engineering, and 12 moreCement, Composite Material, Fly Ash, Bond Strength, Repair, Interdisciplinary Engineering, Alkali Activated Concrete, Civil and Environmental Engineering, Portland cement, environmentally friendly, Oven Curing, and Class C fly ash
Research Interests: Civil Engineering, Materials Science, Design, Iterative Methods, Forecasting, and 15 moreFinite element method, Masonry, Regression Analysis, Displacement, Flexural Strength, Masonry Construction, Masonry Materials, Parametric Statistics, In Plane, Multivariate Regression Analysis, Bending Strength, Multivariant Analysis, Flexure, Retaining Walls, and Analytical framework
This chapter investigates the accuracy of the height-to-thickness ratio (h/t) correction factors presented in the ASTM standard (ASTM C1314-03) and in other international standards using numerical finite element analysis. The FEM is... more
This chapter investigates the accuracy of the height-to-thickness ratio (h/t) correction factors presented in the ASTM standard (ASTM C1314-03) and in other international standards using numerical finite element analysis. The FEM is calibrated with experimental results, and then a parametric study is performed to examine the effect of size on the strength of masonry prisms. Calibration of masonry material provided in this chapter is then used in developing finite element models of PT-MWs presented in Chap. 5.
Research Interests: Civil Engineering, Materials Science, Structural Engineering, Standards, Finite element method, and 14 moreCalibration, Compressive Strength, Masonry, Civil Engineering Materials, Sandwich Structures, Masonry Materials, Materials Testing, Parametric Statistics, Prisms, Correction Factors, Concretes, Concrete Construction, Strength of Concrete, and Compressive Strength of Concrete
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A kind of novel superabsorbent hydrogel with high swelling ratio property that could be used for the development of water absorbing resin, soil water retention agent, and chemical sand-fixing material was synthesized in this study. The... more
A kind of novel superabsorbent hydrogel with high swelling ratio property that could be used for the development of water absorbing resin, soil water retention agent, and chemical sand-fixing material was synthesized in this study. The hydrogels were prepared by the crosslinking reaction of polysuccinimide (PSI). The relationships between swelling ratio and volume of solvent as well as the concentration of crosslinking agent were investigated in detail. Several composites, such as starch, carrageenan, and polyacrylamide, were added into hydrogels to enhance the swelling ratio. It was found that the swelling ratio was significantly increased, which the maximum water absorbency was enhanced 2.46 times when the composite polyacrylamide (PAM) was added compared to the control. The effects of ionic strength and sensitivity of pH on hydrogels were also studied. The modified hydrogels products with swelling ratio less sensitivity to the salinity as well as relative high swelling ration in salinity system were also obtained by adding PAM. Through the Fourier transform infrared spectroscopy (FTIR) characterizations, the crosslinking reaction mechanism and the structure of composite were proposed. In addition, the transmission electron microscopy (TEM) examinations showed that some composite materials elevated the physical crosslinked and connected channels density substantially. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 550–557, 2006
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Unreinforced masonry (URM) buildings represent a large portion of the buildings around the world. Most of these buildings were built with little or no considerations for seismic design requirements. Recent earthquakes have shown that many... more
Unreinforced masonry (URM) buildings represent a large portion of the buildings around the world. Most of these buildings were built with little or no considerations for seismic design requirements. Recent earthquakes have shown that many such buildings are seismically ...
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Water film depth (WFD) is an essential factor regarding road traffic safety on the roads due to its direct connection with skid resistance, hydroplaning speed, and the tendency of splash and spray. Increasing the pavement macrotexture is... more
Water film depth (WFD) is an essential factor regarding road traffic safety on the roads due to its direct connection with skid resistance, hydroplaning speed, and the tendency of splash and spray. Increasing the pavement macrotexture is one of the solutions to reduce the WFD. Therefore, chip seal can be a viable option for reducing the WFD. However, the existing models of WFD prediction are not developed based on highly textured surfaces like chip seal. Besides, the rainfall intensity ranges used for developing most of these models do not raise safety issues on chip seal surfaces. To propose a new WFD prediction model, an experimental study was conducted on 154 different combinations of texture depth, surface material type, surface slope, drainage length, and rainfall intensity using a full-scale rainfall simulator. To study the effects of surface material type and also evaluate the newly proposed eco-friendly rubberized chip seal, mineral aggregate and crumb rubber were used as aggregate. Test results through 1,784 WFD readings indicated that the well-known Gallaway and PAVDRN models are not accurate for chip seal surfaces. Hence, two new analytical models were proposed to predict the WFD, which showed a significantly higher correlation between the actual and the predicted WFD compared to the existing models. Besides, the rubberized chip seal performed an enhanced drainage capability compared to conventional chip seal, especially in low slopes, due to the hydrophobic nature of crumb rubber. Accordingly, the proposed model incorporated a term to consider the effect of surface material type
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Research Interests: Civil Engineering, Geology, Materials Science, Structural Engineering, Stiffness, and 15 moreMasonry, Reinforcement, Flexural Strength, Shear Strength, Masonry structures, Mortar, Masonry Construction, Masonry Materials, In Plane, Experimental Investigations, Concretes, Concrete Construction, Bending Strength, Retaining Walls, and Plane Geometry
Note: 10 pagesCD ROM Reference IMAC-CONF-2004-015 Record created on 2007-06-13, modified on 2016-08-08
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Fiber-reinforced polymer (FRP) has been introduced into civil engineering since last century and finds tremendous applications in retrofitting and constructing infrastructures. Numerous studies have been done on its durability... more
Fiber-reinforced polymer (FRP) has been introduced into civil engineering since last century and finds tremendous applications in retrofitting and constructing infrastructures. Numerous studies have been done on its durability performance; however, most of the test specimens were not applied with mechanical loads while subjecting to environmental conditions, which didn’t reflect the actual service load in a real application. This paper aims to investigate the influence of mechanical loads on concrete-filled FRP tube (CFFT) cylinders while they are under harsh environmental conditions. Both loaded and unloaded specimens were put into an environmental chamber and exposed to freeze/thaw cycles, wet/dry cycles, and heating/cooling cycles for 72 days. Compression tests and split-disk tensile tests were conducted on the CFFT cylinders and the outer FRP tubes, respectively, after the conditioning was completed. Experimental results showed slight reduction on the stress, but considerable de...
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Strengthening is a common process of upgrading the capacity of structural elements to carry additional loads. Out-of-plane flexural behavior of reinforced masonry walls, strengthened with Near-Surface Mounted (NSM) Fiber Reinforced... more
Strengthening is a common process of upgrading the capacity of structural elements to carry additional loads. Out-of-plane flexural behavior of reinforced masonry walls, strengthened with Near-Surface Mounted (NSM) Fiber Reinforced Polymer (FRP) bars or Externally Bonded (EB) FRP sheets and subjected to cyclic loading, was experimentally investigated. Twelve reinforced masonry walls were built for this study. Identical reinforced masonry walls in their unstrengthened form were used as control specimens. Five specimens strengthened using NSM and five specimens with EB were tested. These reinforced walls were strengthened using CFRP and GFRP bars which were placed near the surface (NSM). Also a single ply and a 2-ply wet laid up GFRP in addition to CFRP laminate were used as external reinforcement (EB). A constant reinforcement ratio (ρ) for mild steel was used. The walls were tested in four-point bending with an effective span of 1.12 m between the supports, and subjected to cyclic load with loading rate 1.27 mm/min. This investigation examines the effect of different parameters related to FRP type and amount, and bond pattern (stack and running). The impact of these parameters on the ductility and strength capacity of out-of-plane strengthened wall was evaluated. The force-displacement relationship of the walls and the associated strains in the reinforcement bars and FRP composite were monitored throughout the tests. Different modes of failure occurred in the strengthened reinforced walls, including a punching shear failure through the concrete block, as well as a rupture of FRP and debonding of FRP reinforcement from the masonry substrate
Research Interests: Civil Engineering, Materials Science, Mechanics, Structural Engineering, Structural Design, and 15 moreComparative studies, Masonry, Reinforcement, Composite Material, Flexural Strength, Fibre Reinforced Plastic, Masonry Construction, Masonry Materials, Cyclic Loads, Structural Elements, Carbon Steel, Fiber Reinforced Plastics, Walls (Structural Partitions), Retaining Walls, and Near Surface Mounted
An experimental investigation motivated by a persistent need to produce a sustainable and eco-friendly construction unit with an enhanced thermal insulation to improve power efficiency was undertaken to explore the effects of adding... more
An experimental investigation motivated by a persistent need to produce a sustainable and eco-friendly construction unit with an enhanced thermal insulation to improve power efficiency was undertaken to explore the effects of adding different ratios of crumb rubber as an aggregate replacement to concrete masonry units. Replacement ratios of 0%, 10%, 20%, and 37% were investigated. All of the specimens were put under two different tests that were performed according to ASTM standards C1363-11 and D5334-14 to find the thermal conductivity factor, energy saving, and thermal insulation for the whole masonry units and the new material itself. Guarded hot boxes were fabricated to simulate a real insulation and heat application case. The results indicated that adding the crumb rubber to masonry units had a positive impact on energy saving. Units with a 37% rubber replacement ratio reduced their energy consumption by 41% compared to a conventional masonry unit. A modified thermal needle probe procedure was used to find the thermal conductivity of the rubberized masonry blocks as a material, not a unit. The new rubberized material exhibited a clear reduction in thermal conductivity compared to many commonly used standard construction materials
Research Interests: Engineering, Civil Engineering, Mechanics, Energy Conservation, Energy efficiency, and 14 moreStructural Design, Masonry, Rubber, Thermal Conductivity, Thermal Insulation, Energy efficient, Energy Efficiency, Masonry Materials, Insulation, Experimental Investigations, Energy Utilization, ASTM Standards, power efficiency, and Concrete masonry units
2019Final ReportPDFTech Report25-1121-0005-133-169A3551747107Axial loadsBearing capacityBond strength (Materials)Carbon fibersConcreteCorrosionFiber reinforced polymersFinite element methodPiles (Supports)RepairingRetrofittingSteelSteel... more
2019Final ReportPDFTech Report25-1121-0005-133-169A3551747107Axial loadsBearing capacityBond strength (Materials)Carbon fibersConcreteCorrosionFiber reinforced polymersFinite element methodPiles (Supports)RepairingRetrofittingSteelSteel H-pilesGeopolymer concreteCFRPCorrosionLS-DYNAUnited StatesMid-America Transportation CenterAbdulazeez, Mohanad MRamadan, AmroSherstha, BinodGheni, AhmedGomaa, EslamDarwish, YasserElGawady, MohamedMid-America Transportation CenterMissouri University of Science and TechnologyUnited States. Department of Transportation. Federal Highway AdministrationUS Transportation CollectionThis report summarizes the details of an experimental work and finite element modeling that were conducted to evaluate: 1) the remaining axial capacity of steel H-piles having different corrosion severity and extension levels, and 2) the performance of repaired corroded steel H-piles. The research consisted of 32 short steel H-piles (10 7 42) encased in different types of concrete including conventional concrete, high strength concrete, high-early strength concrete, and geopolymer concrete. Different embedment lengths and shear studs were used. Thirteen long steel H-piles (10 7 42) were milled to represent the loss of cross-sectional area associated with corrosion and tested under concentric and eccentric axial loads. Different corrosion levels and patterns were considered. According to the obtained and observed results from the test, the axial capacity of the concentrically loaded corroded H-piles decreases as the corrosion severity increases. Both the FEMs and experimental work showed that the buckling load is more susceptible to corrosion in the flanges. The length of the corroded region had no effect on the axial load capacity. Increasing the concrete compressive strength increased the bond strength. Furthermore, implementing different concrete jackets types was successful in producing compressive strengths similar to those of the conventional concrete. Using the CFRP jackets without headed studs slightly increased the bond stress between the concrete jackets and steel piles. Using headed studs and CFRP jackets increased the bond strength between the jackets and steel piles by a range of 580% to 1,130%, compared to the reference specimen. Using headed studs considerably increased the bond strength between the concrete jackets and steel piles.82
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AbstractRubberized concrete possesses viscous damping that is higher than that of conventional concrete, making it a promising candidate for construction in high seismic regions. Confining rubberized concrete with glass fiber–reinforced... more
AbstractRubberized concrete possesses viscous damping that is higher than that of conventional concrete, making it a promising candidate for construction in high seismic regions. Confining rubberized concrete with glass fiber–reinforced polymers (GFRP) may result in superior performance. This paper investigates the behavior of rubberized-concrete-filled fiber-reinforced polymer tubes (RCFFT) under different strain rates. The rubberized concrete had 0, 10, and 20% volume replacement of fine aggregate with shredded rubber. Each test specimen’s behavior was compared to that of conventional concrete-filled fiber-reinforced polymer tubes (CFFT). The GFRP tubes were fabricated using wet-layup with different numbers of GFRP layers. Three different strain rates (representing static, earthquake, and severe earthquakes) were used to test these specimens under cyclic axial loading. The RCFFT behaved in a manner that was similar to conventional CFFTs. The rubberized concrete’s confinement limited the reduction in the...
Research Interests: Civil Engineering, Geophysics, Materials Science, Glass, Polymers, and 15 morePolymer, Fibers, Earthquakes, Compressive Strength, Ductility, Composite Material, Reinforced concrete, Confinement, Glass Fiber, Fiber Reinforced Polymers, Beams and Girders, Concretes, Fiber Reinforced Plastics, Bridge Decks, and Plasma confinement
A negative stiffness shell has a convex first position, but can transition or snap to a concave second position under a force applied to the exterior surface of the shell in the convex first position. During the transition, the shell... more
A negative stiffness shell has a convex first position, but can transition or snap to a concave second position under a force applied to the exterior surface of the shell in the convex first position. During the transition, the shell exhibits negative stiffness that permits a large amount of energy to be absorbed. The negative stiffness shell can withstand a high initial force threshold prior to transitioning. In the second, concave position the shell can still resist force. Moreover, it is possible for the shell to revert back to the first, convex position with minimal plastic deformation for subsequent use. The negative stiffness shells can be used collectively and/or in layers to increase the efficiency of the overall negative stiffness shell unit
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This paper experimentally investigates the behavior of concrete-filled-fiber-reinforced polymer (FRP) cylinders under cyclic axial compression. The FRP used in this study were either large rupture strain FRP (LRS-FRP) or hybrid LRS-FRP... more
This paper experimentally investigates the behavior of concrete-filled-fiber-reinforced polymer (FRP) cylinders under cyclic axial compression. The FRP used in this study were either large rupture strain FRP (LRS-FRP) or hybrid LRS-FRP and conventional glass FRP (GFRP). LRS-FRP are manufactured out of polyethylene naphthalate (PEN) and polyethylene terephthalate (PET) obtained from recycled plastics. Hence, they are much cheaper and environment-friendly than conventional GFRP or carbon FRP (CFRP). LRS-FRPs has high tensile rupture strain (usually greater than 5%) compared to 1-2% for GFRP and CFRP. This study presents the results of 4 specimens with different confinement ratios to investigate the behavior of concrete-filled LRS-FRP or hybrid LRS-FRP and GFRP tubes in terms of ductility, ultimate strain, and strength improvement. The results showed that using LRS-FRP significantly improved the ductility of the confined concrete. However, the improvement in strength was limited. The h...
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This paper experimentally investigates the seismic behavior of three large-scale hollow-core fiber-reinforced polymer-concrete-steel (HC-FCS) columns. An HC-FCS column consisted of a concrete shell sandwiched between an outer glass... more
This paper experimentally investigates the seismic behavior of three large-scale hollow-core fiber-reinforced polymer-concrete-steel (HC-FCS) columns. An HC-FCS column consisted of a concrete shell sandwiched between an outer glass fiber-reinforced polymer (GFRP) tube and an inner steel tube. Both tubes provided continuous confinement for the concrete shell along with the height of the column. The columns had two different steel tube diameter-to-thickness (Ds/ts) ratios of 85, and 254. Each steel tube was embedded into the footing, with an embedded length of 1.25-1.6 times its diameter, while the GFRP tube was not embedded into the footing. Two columns were tested as as-built specimens. Then, one of these columns was repaired and re-tested. This study revealed that HC-FCS columns having a high Ds/ts ratio of 254 and short embedded length (1.25 Ds) do not dissipate high levels of energy and display nonlinear elastic performance due to severe steel tube buckling and slippage. However,...
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This paper experimentally investigates the seismic behavior of a large-scale hollow-core fiber-reinforced polymer-concrete-steel HC-FCS column under seismic cyclic loading. The HC-FCS column consisted of a concrete shell sandwiched... more
This paper experimentally investigates the seismic behavior of a large-scale hollow-core fiber-reinforced polymer-concrete-steel HC-FCS column under seismic cyclic loading. The HC-FCS column consisted of a concrete shell sandwiched between an outer fiber-reinforced polymer (FRP) tube and an inner steel tube. The FRP tube provides continuous confinement for the concrete shell along the height of the column while the steel tube provides the required flexural strength. The tested column has an inner steel tube that had a diameter-to-thickness ratio (Di/t) (of 254. The seismic performance of the precast HC-FCS column was compared to that of HC-FCS column having(Di/t) of 64. Three-dimensional numerical models were also developed using LS_DYNA software for modeling the HC-FCS columns. This study revealed that HC-FCS columns having very high (Di/t) and short embedded lengths do not dissipate high levels of energy and display nonlinear elastic performance due to steel tube slippage. However...
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Supplemental material, sj-docx-1-trr-10.1177_03611981211036349 for Water Film Depth Prediction Model for Highly Textured Pavement Surface Drainage by Alireza Pourhassan, Ahmed A. Gheni and Mohamed A. ElGawady in Transportation Research... more
Supplemental material, sj-docx-1-trr-10.1177_03611981211036349 for Water Film Depth Prediction Model for Highly Textured Pavement Surface Drainage by Alireza Pourhassan, Ahmed A. Gheni and Mohamed A. ElGawady in Transportation Research Record
The study reported here investigates the out-of-plane flexure behaviour of reinforced masonry walls strengthened with (NSM) fibre reinforced polymer (FRP) bars and subjected to cyclic loading. An extensive experimental work was carried... more
The study reported here investigates the out-of-plane flexure behaviour of reinforced masonry walls strengthened with (NSM) fibre reinforced polymer (FRP) bars and subjected to cyclic loading. An extensive experimental work was carried out to study the effect of different technique of strengthening using FRP as a NSM or external bonded on out of plan behaviour of reinforced masonry walls. This paper presents part of this extensive study that deals with FRP strengthening using epoxy and cementitious based as an embedding material. Fourteen medium scale reinforced masonry walls were built for this study. These reinforced walls were strengthened using CFRP (bars and tapes) and GFRP (bars) as a near surface mounted technique (NSM); constant mild steel reinforcement ratio (ρ) was used. These simply supported walls were tested under an out-of-plane cyclic load applied along two line loads. This investigation examines the effect of different parameters, these parameters related to FRP (type and amount), bond pattern (stack and running), and existing of FRP bars in compression face of the wall. The test results indicated the behaviour of the masonry walls was significantly dependent on the type of FRP used. A significant increase in the strength of out-of-plane reinforced wall strengthened with FRP compared to the unstrengthened reinforced wall. Different modes of failure occurred in the strengthened reinforced walls, including a punching shear failure through the concrete block, as well as a debonding of FRP reinforcement from the masonry substrate
Research Interests: Civil Engineering, Materials Science, Masonry, Concrete Blocks, Reinforcement, and 12 moreEpoxy, Composite Material, Cementitious Materials, Fibre Reinforced Plastic, Masonry Construction, Masonry Materials, Cyclic Loads, Carbon Steel, Fiber Reinforced Plastics, Walls (Structural Partitions), Retaining Walls, and Near Surface Mounted
This section was monitored for its texture, skid resistance, and aggregate dislodge over a period of one year. The MTD increased significantly with an increase in the rubber content where the MTD of rubberized chip seal with 50%... more
This section was monitored for its texture, skid resistance, and aggregate dislodge over a period of one year. The MTD increased significantly with an increase in the rubber content where the MTD of rubberized chip seal with 50% replacement ratio was increased by 77% compared to the conventional chip seal. Raveling distress was also observed due to snowplowing actions. No damage or any sort of distress was observed in the wheel paths due to traffic loads.
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Class C FAs, sourced from Labadie, Jeffrey, Kansas City, Thomas Hill, and Sikeston power plants in the state of Missouri, were used to synthesize the ZCC. Two different alkali activators (Alk) were used in this study: sodium silicate... more
Class C FAs, sourced from Labadie, Jeffrey, Kansas City, Thomas Hill, and Sikeston power plants in the state of Missouri, were used to synthesize the ZCC. Two different alkali activators (Alk) were used in this study: sodium silicate (SS), Na2SiO3, and sodium hydroxide (SH), NaOH. Slag, crumb rubber, and airentraining admixture (AEA) were used in a few mixtures as additives to improve the durability of the ZCC.
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Many existing unreinforced masonry (URM) buildings are seismically vulnerable and need to be retrofitted. The main structural element that resist earthquakes in these buildings are the old URM walls which were designed to resist mainly... more
Many existing unreinforced masonry (URM) buildings are seismically vulnerable and need to be retrofitted. The main structural element that resist earthquakes in these buildings are the old URM walls which were designed to resist mainly gravity loads. This paper presents the experimental results of testing URM wall including a door opening. The wall was tested before and after retrofitting using glass fiber reinforced polymers (GFRP).The test results were compared to two different assessment guidelines namely FEMA 356 (2000) and Lang (2002).
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Existing unreinforced masonry (URM) buildings have been designed with little or no considerations for the effects of earthquake loadings. Recent earthquakes have demonstrated that these older masonry structures are extremely vulnerable to... more
Existing unreinforced masonry (URM) buildings have been designed with little or no considerations for the effects of earthquake loadings. Recent earthquakes have demonstrated that these older masonry structures are extremely vulnerable to the force imposed during such an event. Numerous techniques are available to increase the strength and/or ductility of URM walls. One promising technique consists of using composites as externally bonded plates to enhance the lateral capacity and/or ductility of URM. While extensive research was conducted and reported for retrofitting of r.c elements using composites, much less has been reported for URM elements. This paper reviews and discuses the state- of-the-art on seismic retrofitting of URM walls using composites. The objective is to provide an overview of the research carried out on URM walls retrofitted using composites with the ultimate goal is to provide a practical guidance for future research in this area. The literature shows that the ...
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This paper numerically investigates the behavior of hollow-core fiber-reinforced polymerconcrete-steel (HC-FCS) building columns under combined axial compression and flexural loadings. The HC-FCS column for buildings consists of an outer... more
This paper numerically investigates the behavior of hollow-core fiber-reinforced polymerconcrete-steel (HC-FCS) building columns under combined axial compression and flexural loadings. The HC-FCS column for buildings consists of an outer circular fiber-reinforced polymer (FRP) tube, an inner square steel tube, and a concrete wall between them. A threedimensional numerical model has been developed using LS_DYNA software for modeling of large scale HC-FCS columns. The nonlinear FE models were designed and validated against experimental results gathered from HC-FCS columns tested under cyclic lateral loading. The FE results were in decent agreement with the experimental backbone curves. These models subsequently were used to conduct a parametric study investigating the effects of the concrete wall thickness, steel tube width-to-thickness (B/t) ratio, and local buckling instability on the behavior of the HC-FCS columns. The obtained local buckling stresses results from the FE models wer...
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This paper presents the mechanical properties of alkali activated concrete (AAC) cured at 70°C for 24 h. The AAC mixtures were synthesized using five class C fly ashes (FAs) having different chemical and physical properties. Sodium... more
This paper presents the mechanical properties of alkali activated concrete (AAC) cured at 70°C for 24 h. The AAC mixtures were synthesized using five class C fly ashes (FAs) having different chemical and physical properties. Sodium hydroxide (SS) and sodium silicate (SH) were used as the alkali activators in this study. A conventional concrete (CC) mixture, having a compressive strength of 34.5 MPa, was synthesized using ordinary Portland cement (OPC) mixture for comparison purposes. The slump, as well as the compressive, tensile splitting, and flexural strengths were investigated at different concrete ages up to 28 days. The results revealed that with increasing the calcium content in an FA used to synthesized AAC mixture, the slump value and the mechanical properties decreased. All AAC mixtures reached approximately 92% of their 28-day compressive strength after 1 day compared with only 29% in the case of CC. Therefore, AAC can be used in applications where rapid strength gain is ...
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An experimental investigation was conducted to investigate the effects of replacing varying percentages of fine natural aggregates with crumb rubber in concrete masonry units (CMUs), creating rubberized concrete masonry units (RCMUs). The... more
An experimental investigation was conducted to investigate the effects of replacing varying percentages of fine natural aggregates with crumb rubber in concrete masonry units (CMUs), creating rubberized concrete masonry units (RCMUs). The mechanical and physical characteristics of RCMUs having 0, 10, 20, and 37% crumb rubber were investigated and presented in this paper. The unit weight and water absorption of RCMUs were measured. A scanning electron microscope (SEM) analysis was used to study the global structure for RCMUs and the interfacial zone. RCMUs were also exposed to extreme weather conditions for 72 days inside an environmental chamber. Furthermore, RCMUs were subjected to rapid freezing-and-thawing tests. The RCMUs, as well as grouted and ungrouted masonry prisms, were tested under monotonic and cyclic axial loads. The results indicated that RCMUs with high rubber content displayed higher values of axial ultimate strains. RCMUs exhibited a significant strain softening while, conversely, failure was quite brittle in CMUs. RCMU specimens exhibited an improvement in compressive strength after several cycles of severe weather exposure. The CMU specimens, however, exhibited degradation in their compression strength capacity. The water absorption was higher in RCMUs than it was in the CMU prisms