International Concrete Abstracts Portal

This volume contains 72 papers from the 10th International Symposium held in Tampa, FL. The papers address internally reinforced members, strengthening of columns, material characterization, bond, emerging fiber-reinforced polymer (FRP) systems, shear strengthening, fatigue and anchorage systems, masonry, extreme events, applications, durability, and strengthening. The papers emphasize the experimental, analytical, and numerical validations of using FRP composites and are aimed at providing insights needed for improving existing guidelines. The increasing maturity and acceptance of FRP is reflected by several papers that provide background information on the recent design codes and guidelines relating to blast and seismic repair. New frontiers of FRP research are explored, addressing emergin materials, and systems and applications for extreme events, such as fires and earthquakes, which will further consolidate FRP’s preeminent position. Note: The individual papers are also available. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP-275

The structural reliability of concrete flexural members reinforced with fiber reinforced polymer (FRP) reinforcement is investigated. Reliability indices based on the equations for flexure in ACI 440.1R-03, which uses the load factors from ACI 318-99 are presented. Choice of a resistance factor for flexure for ACI 440.1R-06, which uses the load factors from ACI 318-02 is also presented. Flexural designs using either ACI 440.1R-03 or ACI 440.1R-06 provide sufficient reliability, with reliability indices between 3.5 and 4.8, with the older versions of ACI 440.1R yielding higher reliability. An analysis of curvature of the beams at failure showed that flexural members that fail by FRP reinforcement rupture have ductilities similar to those that fail by concrete crushing, indicating that FRP reinforcement fracture is not necessarily a more brittle failure mode than concrete crushing.

This paper investigates the design of fiber reinforced polymer (FRP) reinforced concrete based on ACI 440.1R serviceability requirements related to deflection control of one-way slabs and rectangular beams, and uses this information as the basis for evaluating the minimum member thickness requirements needed to satisfy ACI 318 deflection limits. Serviceability is shown to govern design in most cases, as flexural members designed for deflection control are usually stronger than required. Slabs satisfying deflection requirements have a service load that ranges from 20 to 30% of the nominal member capacity, while service loads for beams range from 35 to 45% of the member capacity. Recommended minimum member thickness values for slabs are too conservative and require revision, while those for beams appear reasonable. A practical approach for design of FRP reinforced concrete members is proposed based on selection of member thicknesses needed to satisfy deflection and strength criteria.

This paper presents an experimental study on shear performance of concrete I-beams with fiber reinforced polymers (FRP) as internal reinforcement. A total of four beam tests were conducted, including one test without shear reinforcement and three tests with glass fiber reinforced polymers (GFRP) stirrups. In all specimens, GFRP bars were used as flexural reinforcement. The test variable was the ratio of shear reinforcement. In the test without stirrups, diagonal tension failure occurred. Failure due to rupture of the GFRP stirrups rupture was observed in the test with a shear reinforcement ratio of pw = 0.75% and web crushing failure occurred in the beam tests with pw = 1.26% and pw = 2.26% respectively. The experimentally obtained shear strengths were then compared to calculated design values using equations provided in the modified Eurocode 2, ACI 440.1R06, and CSAS806-2.

Fiber reinforced polymer (FRP) reinforcements, with their excellent mechanical and non-corrosive characteristics are being increasingly used as a replacement for conventional steel reinforcement. ACI 440.1R-06 equation for determining the development length of FRP bars is based on Glass FRP (GFRP) bars and may not be applicable for Carbon FRP (CFRP) bars. This paper presents the results of an experimental study on the flexural behavior, bond characteristics, and development length of concrete beams reinforced with CFRP bars. Twelve beams were fabricated and tested. All beams were tested up to failure using a four point bending regime. The results indicated that the average bond strength of CFRP bars in concrete is about 15% higher than those of GFRP bars at comparable concrete strength. The ACI 440.1R-06 over estimated the development length of the CFRP bars by slightly above 30%, while CAN/CSA-S6-06 equation was unconservative by 50%.