Peeling failure is one of the main drawbacks of reinforced concrete (RC) members strengthened by externally bonded plates. Two different techniques are suggested to prevent peeling failure at the ends of steel plates glued to the soffits of RC beams. In the first technique, concrete cover is replaced by grout to enhance the resistance of substrate to crack initiation and propagation. In the second technique, permanent compressive forces at the ends of bonded plate are applied using different plate end anchorage systems, i.e. end anchorage by bolts or by clamps. Furthermore, two different sizes of side plates, with and without end anchorage, are glued to the plated beam to delay or prevent the peeling failure. An analytical model is suggested to predict the load-deflection behavior of beams strengthened by bonded steel plates at the bottom and sides of the beams. The results of 4PB tests indicate that conventional plated beam (PB) experience reduction in ductility and limited enhancement in ultimate load, which increased only by 22% compared to unplated beams due to the occurrence of peeling failure. Peeling failure of plated beams can be prevented through the use of either a concrete cover replacement technique or bolted anchorage systems. Anchorage of a side plated beam increased the ultimate load by 264% compared to an unplated beam and 217% compared to PB.
The edge-cracked semi-circular bend (SCB) specimen subjected to three-point bending loading is used in many applications to measure the fracture behavior of quasi-brittle materials. The main objective of the present work was to study the effect of the crack length to SCB specimen radius ratio (a/R), span to specimen diameter ratio (S/D), and specimen size on its flexural and mode I crack growth behavior. The contour integral method was implemented using the 3-D finite element method to determine the mode I stress intensity factor. In addition, high-strength concrete specimens were experimentally studied to validate the numerical results. The results show that the maximum compression stress is not sensitive to the S/D value, while the tensile stress is very sensitive. The value of S/D is the main parameter controlling the crack driving force (i.e., the crack mouth opening displacement (CMOD) and the normalized stress intensity factor, YI). For the same S/D, the SCB specimen diameter value change has a marginal effect on CMOD and YI. The specimen with S/D = 0.8 showed that it is the most compatible specimen with three-point bending test conditions, regardless of the SCB specimen size. A good agreement between the numerical and experimental results was achieved.
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