International Concrete Abstracts Portal

This paper presents the test results of 14 full-scale concrete beams. The beams were 3300 mm long with a rectangular cross-section of 200-mm width and 300-mm depth. Twelve beams were reinforced with carbon FRP composite bars and two reinforced with steel as control. Two newly developed types of CFRP bars with different surface textures were considered: the sand-coated ISOROD bars and the ribbed-deformed C-BAR. The beams were tested to failure in four-point bending over a clear span of 2750 mm. The results presented focus on the deflection behaviour of beams reinforced with CFRP bars, which have different bond, elasticity modulus, strain, and strength characteristics. The test results were compared to the predictions of some of the available models (ISIS-M03-01 design manual, ACI 440.1R-01 guidelines, and Razaqpur model). Based on the findings of the study, the validity of the design guidelines and the effectiveness of using the new CFRP bars as reinforcement for concrete beams were established.

SP-210 This Symposium Publication contains papers presented during the 2002 ACI Spring Convention in Detroit, including six papers related to predicting the deflections of concrete members reinforced with fiber-reinforced polymer (FRP) reinforcement: one paper describes two field investigations, two unique laboratory investigations, a paper on estimating the errors in calculating deflections of high-performance concrete slabs, and a comparison of the ACI and EC2 deflection provisions. This volume should be read in association with Symposium Publication SP-203, Code Provisions for Deflection Control in Concrete.

Deflection behavior of high strength concrete (HSC) flexural members reinforced with glass-fiber polymer bars (GFRP) is investigated. Because serviceability plays a significant role in establishing design acceptance for GFRP reinforced concrete beams, accurate modeling of flexural stiffness is critical and he effect of influencing parameters must be considered. This study accounts ofr variations in reinforcement ratio ( r ) for HSC beams. Experimental results from twelve simply supported concrete beams reinforced with GFRP bars are compared with published deflection models to establish analytic accuracy. All samples have a hear-span-to-depth ratio of 9.4 and are overreinforced with respect to a balanced strain design. Results show that the ACI 318 and ACI 440 effective moment-of-inertia expressions greatly overestimate flexural stiffnes, with the degree of inaccuracy dependent upon on reinforcement ratio.

Serviceability of FRP-reinforced concrete structures remains a highly relevant issue as more structures are constructed using the technology. With the recent publication of the ACI 440 doocument "Guide for the Design and Construction of Concrete Reinforced with FRP Bars," the need to examine serviceability-related issues and validate the accuracy of these design guidelines is heightened. A short-span concrete slab bridge was constructed in St. James, Missouri, using precast panels reinforced with FRP bars. The bridge was designed to meet AASHTO load and deflection requirements using the "Guide for the Design and Construction of Concrete Reinforced with FRP Bars." Carbon FRP, as tensile reinforcement, and glass FRP, as shear reinforcement, were utilized. Laboratory testing of one bridge panel that is identical to those installed in the field was conducted using a four-point loading configuration. Field testing of the bridge was also conducted to examine its behavior under service load. A loaded dump truck was placed at various locations along the bridge while deflections were measured and recorded. Similar field tests will be conducted annually fo rthe next three years in an effort to monitor the ong-term performance of the bridge. The results of the laboratory and field tests are summarized herein; a comparison between the theoretical and measured deflection values is made to illustrate the conservative nature of the prescribed design guidelines.

Serviceability of concrete members reinforced with FRP often governs the design. There are two main serviceability criteria to be satisfied: crack width and deflection. Prior to cracking the behaviour of concrete members reinforced with FRP is identical tot ehat of seel reinforced concrete. After cracking, due to the mechanical characteristics of FRP, the curvature increases rapidly. Therefore deflection of FRP reinforced members is typically larger, thus more critical than deflection of comparable members reinforced with steel. Crack width is often portrayed as less significant due to the excellent corrosion resistance of FRP products. However, high sustained strain in FRP at service loads may lead to stress corrosion primarily in glass-fibre reinforced polymer (GFRP), and the width of cracks needs to be limited for aesthetic reasons. This paper deals with the design of concrete reinforced with FRP to satisfy serviceability requirements. To achieve the goal, a simplified mathematical design using charts is developed for ISIS Canada (1) by the authors. The principles involved in developing these charts, and their applicability are discussed. To satisfy the crack width and deflection limitations of these members, allowable stress limits in FRP reinforcement are introduced.