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International Concrete Abstracts Portal

Showing 1-10 of 23 Abstracts search results

Document: 

SP322

Date: 

July 1, 2018

Author(s):

Editor: Raafat El-Hacha

Publication:

Special Publication

Volume:

322

Abstract:

The use of Fiber-reinforced polymer (FRP) composite materials in new construction and repair of concrete structures has been growing rapidly in recent years. FRP provides options and benefits not available using traditional materials. The promise of FRP materials lies in their high-strength, lightweight, noncorrosive, nonconducting, and nonmagnetic properties. ACI Committee 440 has published several guides providing recommendations for the use of FRP materials based on available test data, technical reports, and field applications. The aim of these document is to help practitioners implement FRP technology while providing testimony that design and construction with FRP materials systems is rapidly moving from emerging to mainstream technology.


Document: 

SP322-22

Date: 

June 18, 2018

Author(s):

Jennifer Eisenhauer Tanner, David J. Mukai, Jingang Deng, and Charles W. Dolan

Publication:

Special Publication

Volume:

322

Abstract:

Strength and fatigue testing were conducted on concrete specimens strengthened with three different epoxy systems. These specimens were conditioned in elevated water baths, subjected to fatigue loading, then tested for strength. For all three systems, the bond strength of a single conditioned specimen was at least 90 percent of the bond strength of three samples that had been fatigued but not conditioned in elevated water baths. Because of the limited data the results are anecdotal and only preliminary findings can be drawn from this work.


Document: 

SP322-21

Date: 

June 18, 2018

Author(s):

Mohamed Zawam and Khaled A. Soudki

Publication:

Special Publication

Volume:

322

Abstract:

An experimental study was conducted to determine the transfer length of prestressed Glass Fiber Reinforced Polymer bars. This paper is a part of a broad program that studies the long-term behaviour of GFRP prestressed concrete beams. 16 GFRP prestressed concrete beams were cast in this study. The parameters included were; prestressing level; 300 MPa (44 ksi) and 500 MPa (73 ksi), concrete compressive strength; 30 MPa (4440 psi) and 70 MPa (10000 psi), and the GFRP bar diameter;12Φ (No. 4) and 16Φ (No.5). Accurate estimation of the transfer length is necessary for elastic stress calculations at the service limit state and for the shear design of prestressed members. Strain gauges were used to measure strains on the GFRP bars and DEMEC gauges were used to measure the concrete surface strains at the level of the prestressed GFRP bar to determine the transfer length. The transfer length of 16Φ (No.5) GFRP bars in concrete with compressive strength of 30 MPa (4440 psi) was found to be about 17 db, and 14 db for prestressing levels of 500 MPa (73 ksi) and 300 MPa (44 ksi), respectively. The measured transfer length values were used to improve the transfer length estimates provided by the ACI 440.4 R-04 equation by calibrating the material coefficient factor (αt) used in the ACI equation.


Document: 

SP322-20

Date: 

June 18, 2018

Author(s):

Donna Chen and Raafat El-Hacha

Publication:

Special Publication

Volume:

322

Abstract:

Experimental and analytical investigation into the performance of a special bond system was conducted on small-scale mixed-mode bending (MMB) specimens for implementation in a full-scale hybrid bridge deck system. Full-depth threaded Glass Fiber Reinforced Polymer (GFRP) rods, as a proposed replacement for commonly used GFRP shear studs, in conjunction with an epoxy bonded coarse silica sand aggregate layer, were used at the bond interface between a pultruded GFRP plate and cast-in-place Ultra-High Performance Concrete (UHPC). Findings show that the presence of the threaded GFRP rods increased the strength of the system up to 250% while utilizing 25% of the rod capacity. The full potential of full-depth threaded GFRP rods for bond and crack control can be explored in greater detail in future studies, including the application of nut tightening forces to increase initial clamping forces at the bond interface.


Document: 

SP322-19

Date: 

June 18, 2018

Author(s):

Robin Kalfat and Riadh Al-Mahaidi

Publication:

Special Publication

Volume:

322

Abstract:

The development of fiber composite materials (FRPs) and their application to structural elements as externally bonded reinforcement is an effective means to increase the strength of existing bridge girders in flexure, shear and torsion. Despite the high strength of FRP materials, premature debonding of the FRP from the concrete substrate typically occurs well before the ultimate tensile strength of the material is reached. Recent research has found that the introduction of end anchorage systems such as bidirectional fiber patch anchors has been found to counteract the end peeling and interfacial shear stresses that occur at fiber ends, resulting in much higher material utilisation prior to debond. However, all of the research conducted on patch anchors to date has been based on near-end supported single shear pull tests and the performance of patch anchors when applied to large-scale beams remains to be investigated. The paper presents a finite element analysis of a large-scale bulb T beam which was calibrated using experimental results from the literature. The calibrated model was later modified by the addition of FRP shear strengthening and the inclusion of bidirectional fiber patch anchors which were found to significantly enhance the maximum laminate strains attained prior to beam failure.


Document: 

SP322-18

Date: 

June 18, 2018

Author(s):

Zahra Karim and Antonio Nanni

Publication:

Special Publication

Volume:

322

Abstract:

The bond between external fiber reinforced polymer (FRP) reinforcement and concrete substrate is of critical importance for the effectiveness of this strengthening technology. As a result, the design of reinforced concrete (RC) members strengthened with FRP composites is to account for, among other failure modes, the debonding of the laminate from the substrate. Although analytical and experimental research conducted for over two decades has led to archival publications and guides, no standard test methodology is yet available for shear bond strength evaluation after aggressive environmental conditioning.

This paper aims at studying the durability of the bond strength between carbon FRP (CFRP) laminate and concrete substrate. The set-up consists of a small, plain concrete beam reinforced with an externally-bonded CFRP laminate that is tested under three-point bending. The force that the CFRP laminate can bear before detaching is easily calculated and the effect of accelerated conditioning is thus evaluated. Different environments and times of exposure are considered including 100% relative humidity, saltwater, alkali solution and dry heat. Statistical analysis are carried out to obtain statistical evidence on the effect of both the conditioning environment and the time of exposure on shear bond strength. The test methodology used in this work has the attributes of an effective standard.


Document: 

SP322-17

Date: 

June 18, 2018

Author(s):

Hai Nguyen, Hiroshi Mutsuyoshi, and Wael Zatar

Publication:

Special Publication

Volume:

322

Abstract:

This work presents an experimental investigation of composite girders consisting of precast Ultra-High Performance Fiber-Reinforced Concrete (UHPFRC) slabs placed on pultruded Fiber-Reinforced Polymer (FRP) Igirders. Two control girder specimens and seven large-scale composite girders were tested under static four-point bending. Two series of the FRP-UHPFRC composite girders were examined. H-series girders composed of hybrid carbon/glass FRP (HFRP) I-girders topped with either full-length precast UHPFRC slabs or segmental counterparts. G-series girders included segmental UHPFRC slabs placed on glass-fiber-reinforced polymer (GFRP) I-girders. Twelve precast UHPFRC segments were used in each slab of the segmental composite girders. Either high-strength mortar or epoxy adhesive were used to join the precast UHPFRC segments. The test results revealed that the flexural stiffness of the composite girder with the epoxy-connected segmental precast slabs is almost identical to that of the full-length precast composite girder. The mortar-connected girder exhibited slightly more ductile behavior than the epoxy-connected girder. The G-series girder with thick GFRP plate externally bonded to the soffit of the GFRP Igirder showed pseudo-ductile behavior. All the composite girders demonstrated significant improvements in flexural stiffness and moment-carrying capacity compared with the control FRP I-girders without the UHPFRC slabs.


Document: 

SP322-16

Date: 

June 18, 2018

Author(s):

Scott T. Smith and Huawen Zhang

Publication:

Special Publication

Volume:

322

Abstract:

A commonly reported failure mode through experimentation of fibre-reinforced polymer (FRP)-concrete bonded interfaces is premature debonding of the FRP. Such undesirable failure can occur at strains significantly lower than the strain capacity of the FRP and it can be sudden. Anchorage of the FRP is an intuitive means to delay and even halt debonding, and the addition of anchors can also lead to more deformable FRP-strengthened elements. The so-called FRP anchor has been shown to be an effective anchorage device and while there have been several experimental studies reported to date on FRP-strengthened RC elements anchored with such anchors, there has been decidedly less research on numerical modelling. This paper presents the details of a partial interaction model and a constitutive model for the FRP-to-concrete bonded interface as well as FRP anchors. The models are then used to simulate FRP anchors in single-shear FRP-to-concrete joints. The results of parametric studies on key variables such as plate geometry and plate material properties as well as anchor location and number of anchors are then provided. The parametric studies enable insights to be gained towards the contribution of FRP anchors in FRP-to-concrete bonded interfaces.


Document: 

SP322-15

Date: 

June 18, 2018

Author(s):

Griffith Shapack, Zachary Van Brunt, Rudolf Seracino, Gregory Lucier, Sami Rizkalla, and Mohammad Pour-Ghaz

Publication:

Special Publication

Volume:

322

Abstract:

Steel prestressed cored slab superstructures are a common structural system for multi-span bridges in coastal North Carolina. However, due to the aggressive marine environment several such bridges are in need of major repairs or replacement after being in service for little more than 40 years. To address this issue two research projects were undertaken in parallel. The first project involved a critical assessment of non-destructive evaluation techniques in an attempt to predict the extent of corrosion deterioration and hence, the residual strength of cored slabs from existing bridges. Twelve cored slabs taken from two in-service bridges scheduled for superstructure replacement were tested to failure in the laboratory to validate residual strength predictions. The second project involved the design, manufacture and testing of a full-scale CFRP prestressed cored slab reinforced with GFRP stirrups, and a typical steel prestressed cored slab control specimen. The results of the destructive laboratory testing enabled validation of the prediction of the flexural performance and strength of CFRP prestressed cored slabs relative to existing design recommendations. Direct comparison to the new steel prestressed control cored slab and similar existing cored slabs with varying degrees of deterioration from the first the research project was also undertaken.


Document: 

SP322-14

Date: 

June 18, 2018

Author(s):

Ahmed Abouzied and Radhouane Masmoudi

Publication:

Special Publication

Volume:

322

Abstract:

This paper introduces a rectangular concrete-filled fiber reinforced polymer (FRP) tube (CFFT) hybrid beam with an inner voided tube. The beam contains an outer rectangular filament-wound glass fiber reinforced polymer (GFRP) tube, and an inner voided circular filament-wound GFRP tube shifted toward the tension zone. The space between the tubes is filled with concrete. Steel bars, at the tension side, were provided to enhance both stiffness and serviceability of the beam. The flexural behavior of this voided CFFT beam was compared with a fully CFFT beam and another conventional steel reinforced concrete (RC) beam having identical dimensions. The results showed that the new hybrid composite beam behaves positively in terms of strength, ductility, and failure propagation, in addition to its high durability. The results also showed that, while the weight of the voided CFFT beam is 30% lighter than the weight of the conventional RC beam or the fully CFFT beam, its flexural capacity is 141% and 6% higher than their flexural capacities, respectively.


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