The permissible crack width of concrete members reinforced by reinforcing steels is generally determined by the durability of the member based on reinforcing steel corrosion. However, since FRP reinforcement does not corrode by rusting, another factor should control permissible crack width for FRP reinforced structures. Paper examines permissible crack width of FRP reinforced concrete members in terms of the esthetics of external appearance. As cracks are wider, appearance deteriorates. Since esthetic evaluation is subjective, the authors used a questionnaire survey to gather information from experts. The surveys were completed by members of the JSCE Research Subcommittee on Continuous Fiber Reinforcing Materials. After reviewing a statistical analysis of the results, the authors offer estimates for permissible crack width of FRP reinforced concrete members.

Analysis of the experimental results obtained by testing 45 concrete specimens reinforced with fiber reinforced plastic (FRP) reinforcing bars is outlined. Theoretical correlations with experimental results are conducted in terms of elastic and ultimate bending moment, crack width, and bond and development length. Emphasis is placed on the beam bending analysis and design using regular as well as high-strength (4 to 10 ksi) concrete reinforced with FRP bars by modifying the state-of-the-art design per ACI 318-89 provisions applicable for steel reinforced beams. However, modifications (from the current ACI Building Code) for FRP reinforced beams in terms of ultimate moment capacity, crack pattern, and development length are made without deviating significantly from the design philosophy given in ACI 318-89. Equations for design loads and bending, resistance, bond and development lengths, and crack widths are developed in a simplified form for practical design applications. Similarities and parallels of these design equations with current ACI 318-89 equations are maintained when possible.

The authors introduced bends into FRP rods and, after embedding them in concrete, applied loads to investigate the tensile strength of the bent portions. The results show that the FRP rods ruptured at the bend, and that tensile strength decreases as the curvature of the bend increases. They also indicate that the tensile strength of the bend varies with the strength of concrete, fiber type, and method by which the rods are manufactured. 214-493

PC members reinforced with FRP as tendons show brittle failure regardless of the failure mode. The authors' objective was to improve the ductility of PC members reinforced with FRP as tendons. First, the compressive properties of concrete confined with FRP as transverse reinforcement was investigated. Major improvement can be made in the stress-strain relationship of concrete laterally reinforced with FRP, and the concrete members can be given ductility characteristics similar to those of steel-reinforced members by confining the concrete with FRP. Secondly, several PC members reinforced with FRP as tendons and transverse reinforcement were tested and investigated. It was found that marked improvements could be made in the ductility of PC members with FRP tendons by confining the part of concrete subjected to flexural compression with FRP and forcing the members to undergo flexural compression compression failure. 235-493

The use of fiber reinforced plastic reinforcement in reinforced and prestressed concrete structures is gaining increased attention. This paper describes the results of a preliminary experimental program in which strands made of carbon fiber composites (trade name CFCC - Carbon Fiber Composite Cable) were used as pretensioning reinforcement in two partially prestressed concrete T beams. The beams were ten foot in length and 12 inches in depth and contained, in addition to the carbon fiber strands, conventional reinforcing bars Experience gained with the stressing, anchoring, and releasing of CFCC strands is described. Relevant test results regarding load-deflection response, curvature, stress-increase in the reinforcement with increased load, cracking and crack widths, and failure modes are reported, and compared to results obtained from similar tests using prestressing steel strands. The load deflection response of beams prestressed with CFCC strands showed generally a trilinear ascending branch with decreasing slope up to maximum load. Deflections and crack widths were generally small but increased rapidly upon yielding of the non-prestressed steel reinforcement. The post-peak response was characterized by rapid step-wise decrease in load due to successive failures of the CFCC strands, and stabilization at about the load-carrying capacity of the remaining steel reinforcing bars. The presence of reinforcing bars helped the beams sustain large deflections before crushing of the concrete in the compression zone. Analytical predictions of the load-deflection response using a nonlinear analysis method were used and led to reasonable agreement with experimental results.