02-05-2011, 03:56 PM
Fatigue Behavior of Reinforced Concrete Beams Strengthened with Different FRP Laminate Configurations
Synopsis: This paper presents testing results of thirteen small-scale beams
strengthened using carbon fiber-reinforced polymer composites tested under repeated
loads to investigate their fatigue behavior. The beams were strengthened using
different thicknesses and widths of composite laminates to identify parameters that
would generate different failure modes. Two predominant fatigue failure modes were
identified through these tests: fatigue fracture of the steel reinforcement with
subsequent debonding of the composite laminate, or fatigue fracture of the concrete
layer below the tension reinforcing steel (concrete peel off). Test results indicate that
peak stress applied to the reinforcing steel in combination with composite laminate
configuration are the main parameters that affect the controlling failure mode. Tests on
large-scale components are required to verify the results presented in this paper.
Keywords: carbon fiber-reinforced polymers; fatigue loading;
reinforced concrete; strengthening
614 Gussenhoven and Breña
Maj. Richard Gussenhoven is an Instructor in the Department of Mathematical Sciences
and Assistant Director for the Center of Data Analysis and Statistics in the U.S. Military
Academy at West Point. He received his MS degree at the University of Massachusetts
Amherst in 2004.
Sergio F. Breña is an Assistant Professor at the University of Massachusetts Amherst.
He is a member of ACI Committee 440 – Fiber Reinforced Polymer, ACI 374 –
Performance Based Seismic Design, ACI-ASCE 445 – Shear and Torsion, and ACI 369
Repair and Rehabilitation.
INTRODUCTION
Strengthening existing reinforced concrete structures using composites is an
accepted technology that is being increasingly used in a wide variety of applications.
This technology is particularly promising for bridge applications because of the large
number of existing bridges that need repair or replacement. Additionally some bridge
strengthening applications are required because of an increase in vehicle weight over the
years (Breña et al. 2003). As a result, old bridges designed using lower live-load models
require strengthening to meet current load standards.
Carbon fiber-reinforced polymer (CFRP) composites have been investigated to
strengthen existing older bridges. Many of the studies available in the literature have
been conducted on specimens loaded statically with comparatively few studies performed
using fatigue loading. An understanding of the factors affecting the fatigue performance
of strengthened beams is required to develop appropriate design guidelines for bridge
applications.
RESEARCH OBJECTIVES
The primary objective of this research study was to identify the failure modes
that occur in beams strengthened using CFRP composites and loaded under repeated
loads. Parameters including laminate width and thickness, amplitude of cyclic loading,
and pre-existing damage in the beams were investigated.
DESCRIPTION OF LABORATORY SPECIMENS
Thirteen small-scale beams were fabricated and tested to investigate the effects
of various parameters including composite laminate configuration on their fatigue
performance. Two of these specimens were used as control specimens, and the rest were
strengthened using carbon fiber-reinforced polymer (CFRP) laminates. The CFRP
laminate configuration varied on the strengthened specimens within their respective
specimen group. Details of the strengthening configurations corresponding to each
specimen group are given in the following sections.
DOWNLOAD FULL REPORT
http://www.quakewrapfrp%20papers/FatigueBehaviorofReinforcedConcreteBeamsStrengthenedwithDifferentFRPLaminateConfigurations.pdf
Synopsis: This paper presents testing results of thirteen small-scale beams
strengthened using carbon fiber-reinforced polymer composites tested under repeated
loads to investigate their fatigue behavior. The beams were strengthened using
different thicknesses and widths of composite laminates to identify parameters that
would generate different failure modes. Two predominant fatigue failure modes were
identified through these tests: fatigue fracture of the steel reinforcement with
subsequent debonding of the composite laminate, or fatigue fracture of the concrete
layer below the tension reinforcing steel (concrete peel off). Test results indicate that
peak stress applied to the reinforcing steel in combination with composite laminate
configuration are the main parameters that affect the controlling failure mode. Tests on
large-scale components are required to verify the results presented in this paper.
Keywords: carbon fiber-reinforced polymers; fatigue loading;
reinforced concrete; strengthening
614 Gussenhoven and Breña
Maj. Richard Gussenhoven is an Instructor in the Department of Mathematical Sciences
and Assistant Director for the Center of Data Analysis and Statistics in the U.S. Military
Academy at West Point. He received his MS degree at the University of Massachusetts
Amherst in 2004.
Sergio F. Breña is an Assistant Professor at the University of Massachusetts Amherst.
He is a member of ACI Committee 440 – Fiber Reinforced Polymer, ACI 374 –
Performance Based Seismic Design, ACI-ASCE 445 – Shear and Torsion, and ACI 369
Repair and Rehabilitation.
INTRODUCTION
Strengthening existing reinforced concrete structures using composites is an
accepted technology that is being increasingly used in a wide variety of applications.
This technology is particularly promising for bridge applications because of the large
number of existing bridges that need repair or replacement. Additionally some bridge
strengthening applications are required because of an increase in vehicle weight over the
years (Breña et al. 2003). As a result, old bridges designed using lower live-load models
require strengthening to meet current load standards.
Carbon fiber-reinforced polymer (CFRP) composites have been investigated to
strengthen existing older bridges. Many of the studies available in the literature have
been conducted on specimens loaded statically with comparatively few studies performed
using fatigue loading. An understanding of the factors affecting the fatigue performance
of strengthened beams is required to develop appropriate design guidelines for bridge
applications.
RESEARCH OBJECTIVES
The primary objective of this research study was to identify the failure modes
that occur in beams strengthened using CFRP composites and loaded under repeated
loads. Parameters including laminate width and thickness, amplitude of cyclic loading,
and pre-existing damage in the beams were investigated.
DESCRIPTION OF LABORATORY SPECIMENS
Thirteen small-scale beams were fabricated and tested to investigate the effects
of various parameters including composite laminate configuration on their fatigue
performance. Two of these specimens were used as control specimens, and the rest were
strengthened using carbon fiber-reinforced polymer (CFRP) laminates. The CFRP
laminate configuration varied on the strengthened specimens within their respective
specimen group. Details of the strengthening configurations corresponding to each
specimen group are given in the following sections.
DOWNLOAD FULL REPORT
http://www.quakewrapfrp%20papers/FatigueBehaviorofReinforcedConcreteBeamsStrengthenedwithDifferentFRPLaminateConfigurations.pdf