Experimental and theoretical behavior of reinforced concrete beams and columns strengthened with CFRP.

摘要

The repair and strengthening of concrete structures is a challenging of the concrete industry for both engineers and contractors. Due to increasing economical constraints, the current trend is to repair/upgrade deteriorated and functionally obsolete structures rather than replacing them with new structures. CFRP has been used previously by air space industries regardless of the high costs. The decrease in the costs of the composite materials, as results of the technology improvement, has made CFRP an alternative to conventional materials for many applications.;The first stage of the research program includes the investigation of the influence of number of CFRP layers, CFRP orientation, CFRP volumetric ratio (rhof), concrete compressive strength ( f'c ), and column size on the strength and ductility behavior of reinforced concrete (RC) columns confined externally with CFRP composites. The second stage includes the investigation of the flexural behavior of reinforced concrete (RC) beams externally strengthened with CFRP composites exposed for five years for the following conditions: (a) room temperature, (b) cyclic ponding in 15% salt-water solution, (c) hot-water of 65°C, and (d) rapid freeze/thaw cycles. The third stage includes the investigation of the effect of configuration of strengthening, number of CFRP layers, orientation of CFRP composites, anchoring type, effective depth (d), shear span to depth ratio (a/d), CFRP bonded area with concrete, anchoring systems, and beam depth on shear capacity of reinforced concrete beams externally strengthened with CFRP composites. The fourth stage includes the investigation of the bond slip behavior of bonded CFRP composites. The fifth stage includes the development of an analytical model to predict the stress strain behavior of axially loaded circular reinforced concrete (RC) columns confined by carbon fiber reinforced polymer (CFRP) composites. The sixth stage includes the development of an analytical model to predict the bond slip behavior of bonded CFRP composites with concrete. The sixth stage includes the development of an analytical model to predict the shear strength of reinforced concrete (RC) beams externally strengthened with CFRP composites.