njit-etd2003-032 - New Jersey Institute of Technology

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5 2. A new effective strain model was proposed in the design of the shear strength of RO beams with externally bonded OFRP laminates. 3. Shear strengthening of deep beams using OFRP laminates of various configurations including anchorage effect was studied. 4. The effect of shear span to depth ratio (a i d) was studied in shear strengthening of deep beams using OFRP laminates. 5. Design formulas for shear strengthening of deep beams using OFRP laminates has been proposed and validated. 6. Shear repairing using OFRP laminates for RC beams with previously developed shear cracks was investigated. 1.4 Literature Review The use of fiber reinforced polymer (FRP) in strengthening reinforced concrete structures has become an increasingly popular retrofit technique. The technique of strengthening reinforced concrete structures by externally bonded FRP laminates was started in 198O's and has since attracted many researchers around the world. It was investigated in the USA (Diab, et al., 1984; Saadatmanesh and Ehsani, 1991, 1997; Ohajes, et al., 1994; Nanni, 1995; Hsu, Bian and Jia, 1997; Bian, Hsu and Wang, 1997), Switzerland (Meier, 1987; Meier et al., 1992, Steiner, 1996), Greece (Triantafillou, 1998, 2OOO), Canada (Eriki et al., 1996; Alexander and Oheng, 1996; Ohaallal et al., 1998), Japan and several other European countries.
6 1.4.1 Shear Strength of RC Beams The failures in RC beams that commonly referred to as "shear failures" are actually tension failures at the inclined cracks. One of the earliest to recognize this was E. Morsch in Germany in the early 19OOs. The formation of inclined cracks is due to the high shear stress on a beam, which is particularly true for beams having only longitudinal reinforcements. The transfer of shear in reinforced concrete beams occurs by a combination of the following mechanisms (Wang and Salmon, 1992): 1. Shear resistance of the untracked concrete. 2. Aggregate interlock (or interface shear transfer) force, tangentially along a crack and similar to a frictional force due to irregular interlocking of the aggregates along the rough concrete surfaces on each side of the crack. 3. Dowel action, the resistance of the longitudinal reinforcement to a transverse force. 4. Shear reinforcement resistance, from vertical or inclined stirrups. For rectangular beams without shear reinforcement, it is reported that after an inclined crack has formed, the proportion of the shear transferred by the various mechanisms is as follows: 15 to 25% by dowel action; 2O to 4O% by the untracked concrete compression zone; and 33 to 5O% by aggregate interlock or interface shear transfer (Wang and Salmon, 1992). To provide shear strength by allowing a redistribution of interval forces, the shear reinforcement has three primary functions: (1) to carry part of the shear; (2) to restrict the growth of inclined cracks and thus help maintain aggregate interlock; and (3) to tie the longitudinal reinforcement in place and thereby increase the dowel action.
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 23 and 24: 2 Additionally, special equipment i
Page 25: 4 5. To study the shear span to dep
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
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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
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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
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89 (b) Right Side Figure 4.15 Failu
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91 of the delamination, which consi
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93 Figure 4.18 Failure of Beam Z31-
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95 4.5.4 Beam Group 4 4.5.4.1 Beam
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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
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111 ;how deflections at ultimate lo
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113 All of the lines in Figure 4.28
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115 ratio; line Z-F90 means the var
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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
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Figure 5.3 Distribution of transver
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Figure 5.4 Estimation of effective
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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
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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-
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145 Figure 6.3 Failure of Beam Z22-
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147 6.2.4 Analysis of Test Results
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149 improves the performance of the
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Figure 6.7 Test result of beam Z22-
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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
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APPENDIX A LOAD DEFLECTION CURVES O
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161 Figure A.3 Load deflection curv
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163 Figure A.7 Load deflection curv
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Figure A.11 Load deflection curve o
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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
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APPENDIX C LOAD DEFLECTION CURVES O
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177 Figure C.3 Load deflection curv
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179 Czaderski, Christoph. "Shear St
Page 202:
181 4, No. 4, Nov. 2000, pp. 198-20
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