This thesis presents research completed on the experimental performance of two 6 3/4 in thick bridge deck panels fabricated by the Stongwell Corporation of Bristol, Virginia. The panels are made of off-the-shelf, pultruded glass fiber-reinforced polymer elements, bonded and mechanically fastened together. The testing involved laboratory stiffness tests performed on one deck panel which afterwards, was placed in a field test site at the I-81 Troutville Weigh Station facility. The daily truck traffic over the deck panel at this site is approximately 5400 vehicles. The second deck panel was constructed as a prototype to test benefits of steel thru-rod mechanical connectors. Further, a rubber tire loading patch was developed for the laboratory stiffness and strength tests performed on this second specimen to investigate modes of failure. Both decks made use of a hook bolt type connection to steel support beams in order to reduce damage seen in previous methods of connection. / Master of Science

The primary objective of this research was to examine the strength degradation of Glass Fiber Reinforced Polymer (GFRP) bars at high temperature and alkalinity and determine if an Arrhenius type relationship can be used as a means of projecting life. The work done includes a thorough literature review, experiments and development of strength prediction models. The experimental work involves exposure of GFRP bars incased in cement mortar to lime-water solution at 30, 45 and 57°C. Overall 100 specimens were included in the experimental program. The tensile strength and modulus of elasticity retention after 180 days of exposure at 57°C was 57% and 82% respectively. The secondary objective was to determine the moisture absorption properties of GFRP bars. The moisture absorption data available is till 80 days from the immersion of the specimens in the tank. The collected data was used in the development of strength retention models. Two strength prediction models, Time Shift Method and Fickian Model for moisture absorption are formulated. Using the Fickian Model, strength is predicted for GFRP bars, if used in bridge decks in Roanoke, Virginia. The strength loss predicted was 45% after 50 years of exposure in real life environment. A linear relationship was observed when the moisture content and strength retention were plotted. The study estimates a strength loss higher than the ACI-440H recommended environmental degradation factor of 0.7 to calculate the design ultimate tensile strength. / Master of Science

The primary objective of this project was to test a full-scale prototype of an actual bridge deck containing GFRP bars as the top mat of reinforcement. The purpose of the tests was to verify that the design would resist the loads for which it was designed and provide assurance that the deck would not unexpectedly fail due to the use of this new material. Behavior of the bridge and deck, such as failure load, failure mode, cracking load, crack widths, deflections, and internal stresses, were examined. Four tests were performed on the deck, all of which tested the deck in negative moment regions. From the tests, it was concluded that the design of the deck was very conservative and that unexpected failure should be of no concern. The secondary objective of this project was to comment on the construction of a bridge deck reinforced with GFRP bars and to note its advantages and disadvantages along with a critique of the current state-of-the-art of designing bridge decks with FRP reinforcement. It was found that the advantages of construction with GFRP bars far outweighed the disadvantages, and that the placing of the top mat of GFRP bars was much easier than the placing of the bottom mat of steel bars. It was also concluded that the current state-of-the-art of designing bridge decks reinforced with GFRP is, for the most part, inaccurate in its prediction of behavior and that more research is needed to create more accurate design equations and procedures. Although current methods do not result in accurate predictions of behavior, they do, as mentioned above, result in conservative designs. / Master of Science

Yes / The bond between FRP bars and concrete, the foremost performance for implementation of such reinforcements to corrosion-free concrete structures, is still unsatisfied due to the weak nature of duplex film in the interface. The existing approaches show low efficiency in improving the microstructures and bond between FRP bars and concrete. To address these issues, this paper provided a new approach for improving the bond between FRP bars and concrete by incorporating nanomaterials, as well as explored the modifying mechanisms and established the bond-slip models. For these purposes, the pull-out test, scanning electron microscope observation, as well as energy dispersive spectrometry analysis were performed. The experimental results demonstrated that the presence of nanomaterials increased the ultimate bond strengths between glass/carbon FRP bars and concrete by up to 16.2% and 37.8%, while the corresponding slips decreased by 28.7% and 35.4%, respectively. Such modification effects can be attributed to the optimized intrinsic composition and the reduced pore content of hydration products in the interface, especially in the duplex film, through the nanomaterial enrichment and nano-core effects. The bond-slip relationship between FRP bars and concrete with nanomaterials can be accurately predicted by the mBPE model. / The authors would like to thank the funding offered by the National Science Foundation of China (51978127 and 51908103), and the Fundamental Research Funds for the Central Universities (DUT21RC(3) 039).

Yes / Tests results of three flanged and two rectangular cross-section concrete beams reinforced with carbon fibre reinforced polymer (CFRP) bars are reported. In addition, a companion concrete flanged beam reinforced with steel bars is tested for comparison purposes. The amount of CFRP reinforcement used and flange thickness were the main parameters investigated in the test specimens. One CFRP reinforced concrete rectangular beam exhibited concrete crushing failure mode, whereas the other four CFRP reinforced concrete beams failed due to tensile rupture of CFRP bars. The ACI 440 design guide for FRP reinforced concrete members underestimated the moment capacity of beams failed due to CFRP tensile rupture and reasonably predicted deflections of the beams tested. A simplified theoretical analysis for estimating the moment capacity of concrete flanged beams reinforced with FRP bars was developed. The experimental moment capacity of the CFRP reinforced concrete beams tested compared favourably with that predicted by the theoretical analysis developed.

An investigation on the application of basalt fibre reinforced polymer (BFRP) and carbon fibre reinforced polymer (CFRP) bars as longitudinal reinforcement for simple and continuous concrete slabs is presented. Eight continuously and four simply concrete slabs were constructed and tested to failure. Two continuously supported steel reinforced concrete slabs were also tested for comparison purposes. The slabs were classified into two groups according to the type of FRP bars. All slabs tested were 500 mm in width and 150 mm in depth. The simply supported slabs had a span of 2000 mm, whereas the continuous slabs had two equal spans, each of 2000 mm. Different combinations of under and over FRP (BFRP/CFRP) reinforcement at the top and bottom layers of slabs were investigated. The continuously supported BFRP and CFRP reinforced concrete slabs exhibited larger deflections and wider cracks than the counterpart reinforced with steel. The experimental results showed that increasing the bottom mid-span FRP reinforcement of continuous slabs is more effective than the top over middle support FRP reinforcement in improving the load capacity and reducing mid-span deflections. Design guidelines have been validated against experimental results of FRP reinforced concrete slabs tested. ISIS-M03-07 and CSA S806-06 equations reasonably predicted the deflections of the slabs tested. However, ACI 440-1R-06 underestimated the deflections, overestimated the moment capacities at mid-span and over support sections, and reasonably predicted the load capacity of the continuous slabs tested. On the analytical side, a numerical technique consisting of sectional and longitudinal analyses has been developed to predict the moment-curvature relationship, moment capacity and load-deflection of FRP reinforced concrete members. The numerical technique has been validated against the experimental test results obtained from the current research and those reported in the literature. A parametric study using the numerical technique developed has also been conducted to examine the influence of FRP reinforcement ratio, concrete compressive strength and type of reinforcement on the performance of continuous FRP reinforced concrete slabs. Increasing the concrete compressive strength decreased the curvature of the reinforced section with FRP bars. Moreover, in the simple and continuous FRP reinforced concrete slabs, increasing the FRP reinforcement at the bottom layer fairly reduced and controlled deflections.

Master of Science / Department of Civil Engineering / Hayder A. Rasheed / The Kansas Department of Transportation’s (KDOT) Bridge 059-045 is a reinforced concrete box girder bridge constructed in 1965 to connect the rural Shawnee Drive across Interstate 135 near McPhearson, Kansas, in between Salina and Wichita. The bridge was observed, during an annual inspection in 1998, to have experienced some settlement, which was further found to be due to its proximity to a sinkhole. This settlement progressed to noticeable levels in 2012 necessitating a semi-annual elevation profile survey that was consistently conducted by KDOT. In April 2016, KDOT determined that the bridge required a detailed finite element analysis to determine the safety and suitability of the bridge to stay open to traffic. Accordingly, a two-level Finite Element Analysis was performed using RISA 3D and Abaqus to assess the level of distress in the bridge due to the continuous differential settlement as a result of the active sinkhole deep in the soil under the bridge. The force-moment results were taken from the RISA 3D model for further analysis of various structural components that make up the bridge, including the box girder, piers, and piles. The stress distribution results from the Abaqus model were investigated for the same components of the bridge. A strengthening design scheme using near surface mounted fiber reinforced polymer rebar was developed to extend the service life of the bridge.

An investigation on the application of basalt fibre reinforced polymer (BFRP) and carbon fibre reinforced polymer (CFRP) bars as longitudinal reinforcement for simple and continuous concrete slabs is presented. Eight continuously and four simply concrete slabs were constructed and tested to failure. Two continuously supported steel reinforced concrete slabs were also tested for comparison purposes. The slabs were classified into two groups according to the type of FRP bars. All slabs tested were 500 mm in width and 150 mm in depth. The simply supported slabs had a span of 2000 mm, whereas the continuous slabs had two equal spans, each of 2000 mm. Different combinations of under and over FRP (BFRP/CFRP) reinforcement at the top and bottom layers of slabs were investigated. The continuously supported BFRP and CFRP reinforced concrete slabs exhibited larger deflections and wider cracks than the counterpart reinforced with steel. The experimental results showed that increasing the bottom mid-span FRP reinforcement of continuous slabs is more effective than the top over middle support FRP reinforcement in improving the load capacity and reducing mid-span deflections. Design guidelines have been validated against experimental results of FRP reinforced concrete slabs tested. ISIS¿M03¿07 and CSA S806-06 equations reasonably predicted the deflections of the slabs tested. However, ACI 440¿1R-06 underestimated the deflections, overestimated the moment capacities at mid-span and over support sections, and reasonably predicted the load capacity of the continuous slabs tested. On the analytical side, a numerical technique consisting of sectional and longitudinal analyses has been developed to predict the moment¿curvature relationship, moment capacity and load-deflection of FRP reinforced concrete members. The numerical technique has been validated against the experimental test results obtained from the current research and those reported in the literature. A parametric study using the numerical technique developed has also been conducted to examine the influence of FRP reinforcement ratio, concrete compressive strength and type of reinforcement on the performance of continuous FRP reinforced concrete slabs. Increasing the concrete compressive strength decreased the curvature of the reinforced section with FRP bars. Moreover, in the simple and continuous FRP reinforced concrete slabs, increasing the FRP reinforcement at the bottom layer fairly reduced and controlled deflections.

No description available.

Doctor of Philosophy / Department of Civil Engineering / Hayder Rasheed / Recent applications in reinforced concrete columns, including strengthening and extreme loading events, necessitate the development of specialized nonlinear analysis methods to predict the confined interaction domain of axial force, shear, and bending moment in square and slightly rectangular concrete columns. Fiber-reinforced polymer (FRP) materials are commonly used in strengthening applications due to their superior properties such as high strength-to-weight ratio, high energy absorption and excellent corrosion resistance. FRP wrapping of concrete columns is done to enhance the ultimate strength due to the confinement effect, which is normally induced by steel ties. The existence of the two confinement systems changes the nature of the problem. Existing research focused on a single confinement system. Also, very limited research on rectangular sections was found in the literature. In this research, a model to estimate the combined behavior of the two systems in rectangular columns is proposed. The calculation of the effective lateral pressure is based on Lam and Teng model and Mander model for FRP wraps and steel ties, respectively. The proposed model introduces load eccentricity as a parameter that affects the compression zone size, and in turn the level of confinement engagement. Full confinement corresponds to zero eccentricity, while unconfined behavior corresponds to infinite eccentricity. The model then generates curves for eccentricities within these boundaries. The numerical approach developed has then been extended to account for shear interaction using the simplified modified compression field theory adopted by AASHTO LRFD Bridge Design Specifications 2014. Comparisons were then performed against experimental data and Response-2000, an analytical analysis tool based on AASHTO 1999 in order to validate the interaction domain generated. Finally, the developed models were implemented in the confined analysis software “KDOT Column Expert” to add FRP confinement effect and shear interaction.