njit-etd2003-032 - New Jersey Institute of Technology

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CHAPTER 1 INTRODUCTION 1.1 General It is well known now that a significant part of the infrastructure in North America is in urgent need of strengthening and rehabilitation. As documented in the eleventh report of the Secretary of Transportation to the Oongress of the United States on "Highway Bridge Replacement and Rehabilitation Program", over one third of the nation's 575,413 inventoried highway bridges are classified as either structurally deficient or functionally obsolete (FHA 1993). According to OERF, Civil Engineering Research Foundation, ASCE (1994), 4O% of the nation's bridges are structurally deficient or functionally obsolete, 6O% of the nation's pavement requires rehabilitation. The cost of replacing all deficient structures is prohibitive. Limited financial resources and current technology together will not be enough to solve the problem. High-tech solutions must be investigated so innovative use of new technologies and materials can be employed to rebuild the infrastructure. Historically, concrete members have been repaired by post tensioning or jacketing with new concrete in conjunction with a surface adhesive (Klaiber et al. 1987). Since the mid 196O's, epoxy-bonded steel plates have been used in Europe and South Africa to retrofit flexural members (Dussek 1987). However, steel plates have a durability problem unique to this application, because corrosion may occur along the adhesive interface. This type of corrosion adversely affects the bond at the steel plateiconcrete interface and is difficult to monitor during routine inspections. The problem was extremely worse in the United States, where deicing salts were heavily used to enhance winter road safety. 1
2 Additionally, special equipment is necessary to install the heavy plates. Engineers have to search for alternative materials. In past twenty years, a new technique has been developed involving the replacement of steel plates by fiber reinforced polymers (FRP), or simply composites, wrapped or epoxy-bonded to the web or tension side of concrete, in the form of thin laminates or fabric. Fiber reinforced plastic materials have been used successfully in the aerospace and automotive industry for more than three decades. They are generally constructed of high performance fibers such as carbon, aramid, or, glass which are placed in a resin matrix. By selecting among the many available fibers, geometry and polymers, the mechanical and durability properties can be tailored for particular application. This synthetic quality makes FRP a good choice for civil engineering application as well. The FRP offer the engineer an outstanding combination of properties, such as low weight (making them much easier to handle on site), immunity to corrosion, excellent mechanical strength and stiffness, and the ability of formation in very long length, thus eliminating the need for lapping at joints. Although FRP is a relatively expensive material compare to steel, the total rehabilitation project costs is about 2O% (Mufti, et al., 1991) lower by using FRP than steel due to the savings in construction expenses. The FRPstrengthening technique has found wide attractiveness and acceptance among researchers and engineers today in many parts of the world.
Page 1 and 2: Copyright Warning & Restrictions Th
Page 3 and 4: ABSTRACT SHEAR STRENGTHENING OF RC
Page 5 and 6: SHEAR STRENGTHENING OF RC BEAMS USI
Page 7 and 8: APPROVAL PAGE SHEAR STRENGTHENING O
Page 9 and 10: This dissertation is dedicated to m
Page 11 and 12: TABLE OF CONTENTS Chapter Page 1 IN
Page 13 and 14: TABLE OF CONTENTS (Continued) Chapt
Page 15 and 16: LIST OF TABLES Chapter Page 2.1 Max
Page 17 and 18: LIST OF FIGURES (Continued) Chapter
Page 19 and 20: LIST OF FIGURES (Continued) Chapter
Page 21: LIST OF FIGURES (Continued) Chapter
Page 25 and 26: 4 5. To study the shear span to dep
Page 27 and 28: 6 1.4.1 Shear Strength of RC Beams
Page 29 and 30: Where A, is the area of shear reinf
Page 31 and 32: 10 usually be the same throughout t
Page 33 and 34: 12 1.4.2.2 Shear Strength of Contin
Page 35 and 36: 14 based on the assumption that the
Page 37 and 38: CHAPTER 2 EXPERIMENTAL PROGRAM ON S
Page 39 and 40: 18 needed, which was 4Omm wide and
Page 41: 20 used for bonding of the strips t
Page 45 and 46: 24 2.2 Instrumentation and Test Pro
Page 47 and 48: 26 b) Beam Z4-90 The next beam was
Page 49 and 50: 28 CFRP strip suddenly detached fro
Page 51 and 52: 30 Figure 2.17 Failure of Beam ZC6.
Page 53 and 54: 32 capacity. The load went straight
Page 55 and 56: 34 Figure 2.22 Failure of Beam Z6-9
Page 58 and 59: 37 c) Failure Mechanism Apparently,
Page 60 and 61: 39 observed by a prolonged portion
Page 63 and 64: 42 c) Failure Mechanism Since diffe
Page 65 and 66: 44 The equation to compute CARP she
Page 67 and 68: 46 3.2 Design Approach Based on Mod
Page 70: 49 Arom Aigure 3.2, it can be obser
Page 74 and 75:
53 Equation 3.12 from curve fitting
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55 strength. The method based on bo
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57 Chajes, M. J. et al. (1996) also
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3) CFRP continuous fiber sheet in t
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Figure 3.11 CARP strip in the form
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63 Thus, a relationship between the
Page 86 and 87:
65 2 fc bi,d I f =wife • t f ' fi
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67 Arom Table 3.4, it can also be o
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69 equal to 3.75, the beam specimen
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71 laminates. The surfaces of the f
Page 94 and 95:
Figure 4.3 Configuration of CARP st
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75 16 beams were tested in this res
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79 Figure 4.7 Typical test setup. 4
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81 intact. The CFRP strip delaminat
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83 4.5.1.4 Beam Z11-S45. The CFRP s
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85 4.5.2 Beam Group 2 4.5.2.1 Beam
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87 4.5.2.3 Beam Z22-S90. This beam
Page 110 and 111:
89 (b) Right Side Figure 4.15 Failu
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91 of the delamination, which consi
Page 114 and 115:
93 Figure 4.18 Failure of Beam Z31-
Page 116 and 117:
95 4.5.4 Beam Group 4 4.5.4.1 Beam
Page 118 and 119:
97 4.5.4.3 Beam Z42-FD. This was th
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99 (a) Side View of the Beam at Fai
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101 4.6 Test Results and Discussion
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103 failure along the inclined crac
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105
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107 4.6.3 Beam Group 3 A summary of
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109 4.6.3.3 Failure Mechanism. No i
Page 132 and 133:
111 ;how deflections at ultimate lo
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113 All of the lines in Figure 4.28
Page 136 and 137:
115 ratio; line Z-F90 means the var
Page 138 and 139:
117 Unlike regular beams with large
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119 orientation of the CFRP strips
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121 As for shear design of deep bea
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123 provisions of ACI Code (ACI 318
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125 stress due to shear as well as
Page 148 and 149:
Figure 5.3 Distribution of transver
Page 150 and 151:
Figure 5.4 Estimation of effective
Page 152 and 153:
131 Where A and Ah are the areas of
Page 154 and 155:
Since the principal tensile stress
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135 laminates can be obtained from
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Table 5.1 Experimental and Computed
Page 160 and 161:
139 Where i denote each type of rei
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141 the strongest beam in the 4-foo
Page 164 and 165:
143 Figure 6.1 Failure of Beam ZC4-
Page 166 and 167:
145 Figure 6.3 Failure of Beam Z22-
Page 168 and 169:
147 6.2.4 Analysis of Test Results
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149 improves the performance of the
Page 172 and 173:
Figure 6.7 Test result of beam Z22-
Page 174 and 175:
Figure 6.8 Test result of Beam Z3I-
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155 equal to 69 degrees in this cas
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157 decreases, while the shear cont
Page 180 and 181:
APPENDIX A LOAD DEFLECTION CURVES O
Page 182 and 183:
161 Figure A.3 Load deflection curv
Page 184 and 185:
163 Figure A.7 Load deflection curv
Page 186 and 187:
Figure A.11 Load deflection curve o
Page 188 and 189:
167 Figure B.1 Load deflection curv
Page 190 and 191:
Page 192 and 193:
Page 194 and 195:
173 Figure B.13 Load deflection cur
Page 196 and 197:
APPENDIX C LOAD DEFLECTION CURVES O
Page 198 and 199:
177 Figure C.3 Load deflection curv
Page 200 and 201:
179 Czaderski, Christoph. "Shear St
Page 202:
181 4, No. 4, Nov. 2000, pp. 198-20
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