Delamination in reinforced concrete retrofitted with fiber reinforced plastics
Name
45233863-MIT.pdf
Description
Full printable version
Size
20.1 MB
Format
Adobe PDF
Checksum (MD5)
95449a4c36f34873d37e6936e0ad457d
Author(s)
Hearing, Brian Phillip, 1972-
Advisor(s)
Oral Buyukozturk.
Date Issued
2000
Publisher
Massachusetts Institute of Technology
Abstract
The addition of fiber-reinforced plastic (FRP) laminates bonded to the tension face of concrete members is becoming an attractive solution to the rehabilitation and retrofit of damaged structural systems. Flexural strength is enhanced with this method but the failure behavior of the system can become more brittle, often involving delamination of the composite. This study investigates failure modes including delamination with the use of fiber reinforced plastics to rehabilitate various concrete structures. The focus is on delamination and its causes, specifically in the presence of existing cracks in the retrofitted concrete system. First, delamination processes in FRP retrofitted concrete systems are studied through combined experimental and analytical procedures. The delamination process is observed to initiate in the concrete substrate with micro cracks that coalesce into an unstable macro crack at failure. This macroscopic behavior is modeled through a finite element procedure with a smeared crack approach, which is found to be limited in the ability to represent the stress intensity at the delamination tip. For this reason it is shown that interfacial fracture mechanics can be used to describe the bimaterial elasticity and complex stress intensity at the delamination tip and provide a criterion governing the propagation of delamination using energy methods. Then, peeling processes occurring at existing cracks in the retrofitted system are studied through fracture mechanics based experimental and analytical procedures. An experimental program involving specialized shear notch specimens demonstrates that the location of the notch and laminate development length are influential on the shear crack peeling process. A finite element procedure is used to evaluate the crack driving forces applied at the shear notch crack mouth, and the fracture analysis is extended to evaluate initiation of peeling at the shear notch scenario. Finally, delamination failures in FRP retrofitted reinforced concrete beams representing "real-life" retrofit scenarios are investigated. An experimental and analytical program is conducted to investigate influences on the failure processes. The application of the fracture based peeling analysis to a quantitative design procedure is investigated, and a computational design aid to assist the iterative design procedure is developed.
Description
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2000.
Includes bibliographical references (leaves 251-269).
Subjects
Civil and Environmental Engineering.
MIT Department
Massachusetts Institute of Technology. Department of Civil and Environmental Engineering
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