International Concrete Abstracts Portal

An innovative corrosion-free system for short- and medium-span bridgesconsisting of precast prestressed concrete truss girders and cast-in-situ concrete deckhas been developed. Advantages of the new system include reduced self-weight andenhanced durability. The girders consist of top and bottom concrete flanges connectedby precast vertical and diagonal members made of fiber reinforced polymer (FRP) tubesfilled with concrete. Glass FRP dowels and corrosion-resistant steel stud reinforcementare used, respectively, to connect the vertical and diagonal members to the concreteflanges. The flanges are pretentioned with carbon FRP tendons. The deck slab isreinforced with corrosion-resistant steel bars in the bottom transverse layer and withglass FRP bars in the bottom longitudinal and the top layers. The girders may be post-tensioned with external carbon FRP tendons to balance the slab weight and to providecontinuity in multi-span bridges. The general details of the system and an experimentalevaluation of its critical components, namely, the FRP tubes and the truss connection,are presented. Three types of FRP tube and four types of connection are investigated.The results of testing eight connection specimens under static loading are presented.The tests have shown superior performance of the connection when filament woundtubes and continuous double-headed studs are used.

This two volume set contains 95 papers from the 7th International Symposium and includes chapters devoted to materials characterization, masonry, bond, external strengthening, serviceability, design and behavior of members internally reinforced with FRP composites, FRP used for confinement, field applications, extreme events, and durability. The technical papers not only emphasize the experimental, analytical, and numerical validations of using FRP composites for externally strengthening or internally reinforcing concrete structures, but most are aimed at providing the insight needed for improving existing design guidelines. Several papers discuss the proposed design guidelines for deflections, shear strength, and reinforcing masonry, which practitioners should find useful. New applications are also featured, including studies and design equations for the use of near-surface-mounted FRP products, use of steel-reinforced polymer for reinforcing concrete, and the use of FRP to retrofit structures for blast mitigation. FRP composites performance is presented in chapters on durability and extreme events. Note: The individual papers are also available as .pdf downloads.. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP230

This paper presents an analytical investigation conducted to study theflexural behavior of reinforced concrete beams strengthened with various Near-SurfaceMounted (NSM) Fiber-Reinforced Polymers (FRP) reinforcements. The materials used inthis investigation included carbon-fiber-reinforced-polymer (CFRP) rebars and strips,and glass fiber-reinforced-polymer (GFRP) rebars and strips. The analysis included theeffects of strengthening on the serviceability and ultimate limit states as well the effectof tension stiffening. The effectiveness of NSM FRP rebars and strips was examined andcompared to externally bonded (EB) FRP strips and sheets using the same material typeand axial stiffness. Results from the analytical models were compared with thoseobtained from experimental studies. The analytical results agree very well with thoseobtained from the experimental results. It was found that the analytical model couldeffectively simulate the behaviour of the reinforced concrete beams strengthened withvarious NSM FRP and EB FRP reinforcements. Using the same axial stiffness of FRP tostrengthen reinforced concrete beams, the beams strengthened with NSM FRPreinforcement achieved higher ultimate load than beams strengthened with EB FRPreinforcement. This result is due to the high utilization of the tensile strength of the FRPreinforcement.

Unreinforced masonry (URM) walls are prone to failure when subjected toout-of-plane loads caused by seismic loads or high wind pressure. Fiber ReinforcedPolymers (FRP) in the form of laminates or grids adhesively bonded to the masonrysurface with epoxy or polyurea based resins; or FRP bars used as Near SurfaceMounted (NSM) reinforcement bonded to the masonry using epoxy or latex modifiedcementitious pastes, have been successfully used to increase flexural and/or shearcapacity of URM walls. However, the practical application of FRPs to strengthenmasonry structures is only limited to few research projects due to the limited presenceof specific design guidelines. This paper describes provisional design guidelines for theFRP strengthening of masonry walls subject to out of plane loads. The proposed designmethodology offers a first rational attempt for consideration by engineers interested inout-of-plane upgrade of masonry walls with externally bonded FRP systems.

Unreinforced masonry building specimens were evaluated under cycliclateral loading. Various fiber reinforced polymer (FRP) composite configurations wereused to repair and retrofit the masonry structures. In the first phase, three differentcomposite systems were used to repair pre-damaged masonry structures. Thesesystems included: a wet lay-up woven glass fabric; a near surface mounted (NSM)extruded carbon FRP plate; and a glass FRP grid attached via a high elongationpolyurea resin. Retesting of the repaired structures revealed increases as much as700% in terms of energy dissipation and 300% in terms of pseudo-ductility. The secondphase involved retrofitting similar undamaged building specimens with FRP composites.Significant increases in strength, ductility and energy dissipation were observed. Theseismic performance of each structure was increased with the addition of a minimalamount of composite material as compared to the unreinforced structures.