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- Title
- experimental and numerical investigations on bond durability of cfrp strengthened concrete members subjected to environmental exposure.
- Creator
-
Al-Jelawy, Haider, Mackie, Kevin, Gou, Jihua, Chopra, Manoj, University of Central Florida
- Abstract / Description
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Fiber reinforced polymer (FRP) composites have become an attractive alternative to conventional methods for external-strengthening of civil infrastructure, particularly as applied to flexural strengthening of reinforced concrete (RC) members. However, durability of the bond between FRP composite and concrete has shown degradation under some aggressive environments. Although numerous studies have been conducted on concrete members strengthened with FRP composites, most of those studies have...
Show moreFiber reinforced polymer (FRP) composites have become an attractive alternative to conventional methods for external-strengthening of civil infrastructure, particularly as applied to flexural strengthening of reinforced concrete (RC) members. However, durability of the bond between FRP composite and concrete has shown degradation under some aggressive environments. Although numerous studies have been conducted on concrete members strengthened with FRP composites, most of those studies have focused on the degradation of FRP material itself, relatively few on bond behavior under repeated mechanical and environmental loading.This thesis investigates bond durability under accelerated environmental conditioning of two FRP systems commonly employed in civil infrastructure strengthening: epoxy and polyurethane systems. Five environments were considered under three different conditioning durations (3 months, 6 months, and 1 year). For each conditioning environment and duration (including controls), the following were laboratory tested: concrete cylinders, FRP tensile coupons, and FRP-strengthened concrete flexural members. Numerical investigations were performed using MSC MARC finite element software package to support the outcomes of durability experimental tests. Precise numerical studies need an accurate model for the bond between FRP and concrete, a linear brittle model is proposed in this work that is calibrated based on nonlinear regression of existing experimental lap shear data.Results of tensile tests on FRP coupons indicate that both epoxy and polyurethane FRP systems do not degrade significantly under environmental exposure. However, flexural tests on the FRP strengthened concrete beams indicate that bond between FRP and concrete shows significant degradation, especially for aqueous exposure. Moreover, a protective coating suppresses the measured degradation. Also, experimental load-displacement curves for control beams show excellent agreement with numerical load-displacement curves obtained using the proposed bond model. Finally, a bond-slip model is predicted for concrete leachate conditioned beams by matching load-displacement curves for those beams with numerical load-displacement curves.
Show less - Date Issued
- 2013
- Identifier
- CFE0004971, ucf:49589
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004971
- Title
- Shifted Plastic Hinge Column Connections Using Grouted Sleeves for Accelerated Bridge Construction.
- Creator
-
Al-Jelawy, Haider, Mackie, Kevin, Gou, Jihua, Chopra, Manoj, University of Central Florida
- Abstract / Description
-
Accelerated bridge construction (ABC) is being increasingly used in new bridge construction and repair. ABC typically requires prefabricated elements joined with mechanical couplers. Grouted sleeves (GSs) offer good construction tolerances and load transfer between precast elements. However, previous research identified some performance issues with precast columns employing GS connections for seismic regions. Therefore, there is a need to develop improved connection details. This research...
Show moreAccelerated bridge construction (ABC) is being increasingly used in new bridge construction and repair. ABC typically requires prefabricated elements joined with mechanical couplers. Grouted sleeves (GSs) offer good construction tolerances and load transfer between precast elements. However, previous research identified some performance issues with precast columns employing GS connections for seismic regions. Therefore, there is a need to develop improved connection details. This research consists of three components; testing of six large-scale precast reinforced concrete column models, a series of individual component tests on GS bar splices, and analytical studies. Large-scale, precast column models were designed and experimentally tested using a shifted plastic hinge (SPH) concept to minimize the damage in the capacity-protected elements and retain the column ductility. The column testing matrix considered aspect ratio, moment gradient, and splicing details. Column models were tested in an upright cantilever configuration under quasi-static cyclic load. Results showed that SPH can be used for both flexural and flexural-shear columns. Two types of component tests were performed: tensile tests to quantify the tensile behavior of the splices, and strain penetration tests to quantify the slip at the sleeve ends. The tests were used to obtain constitutive models for the bond-slip behavior of the GS splices.Results showed that GS splices developed the full ultimate stress of the spliced bars and that the slip at sleeve ends can considerably influence the global behavior of the precast columns. The analytical models were developed in OpenSees using fiber-based beams models and they incorporated the calibrated bond-slip models of GS splices. The large-scale column tests were simulated and compared with respective experimental results. Analytical results showed that the developed models were able to mimic the column behavior and can be used for analysis of GS precast columns.
Show less - Date Issued
- 2017
- Identifier
- CFE0006851, ucf:51739
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006851