International Concrete Abstracts Portal

This paper describes the Joffre Bridge project where Carbon Fiber Reinforced Polymer (CFRP) was used as reinforcement for a portion of the concrete deck-slab is reinforced with reinforcement. The Joffre bridge, located over the St-François River in Sherbrooke, Quebec, Canada, consists of five longitudinal spans with length varying from 26 to 37 meters. Each span consists of a concrete deck supported by five steel girders at 3.7 meters. This spacing constitutes the highest span using FRP reinforcement. A Part of the concrete deck slab (7.3 m x 11.5 m) and a portion of the traffic barrier and the sidewalk was reinforced with Carbon and Glass Fiber Reinforced Polymer (FRP ) reinforcement. In addition, four FRP reinforced full-scale one-way concrete slabs were laboratory tested under static and cyclic loading, in order to optimize the design process. The bridge was extensively instrumented with different types of sensors, including integrated fiber optic sensors in FRP reinforcement that were integrated into the FRP reinforcement. The results of the laboratory study, in terms of deflection and crack-width versus applied load, as well as the results of calibrated loads, using heavy trucks, are also presented in this paper.

Upgrading often becomes a necessity due to changes in usage of buildings due to factors such as deterioration and aging, change in occupancy, or the need for installation of facilities such as air-conditioning, heating, escalators, elevators, additional skylights, or new façade structures. In a number of cases upgrading is related to changes which affect the load bearing components of the structure. Fiber reinforced polymer matrix composites provide an efficient means of both strengthening slabs for enhanced load carrying capacity and for strengthening slabs after installation of cut-outs. This paper reports on a series of tests conducted to assess the comparative efficiencies of a commercially available strip form and a fabric form of material vis-à-vis strengthening ability and ductility. It is shown that material tailoring can result in significant changes in efficiencies. The extension of this to the rehabilitation of cut-outs is also detailed and aspects of an on-going full-scale test program in that area are elucidated.

Using the database consisting of 236 R/C column specimens conducted in Japan, the characteristic behaviors of strengthening by fiber wrapping were analyzed. The following findings were obtained: (1) The amount of shear reinforcement, the span to depth ratio, the axial compressive stress level influence on the strength and deformation capacities of retrofitted columns by fiber sheet wrapping (2) Shear strength of retrofitted columns can be predicted by previous design equations based on the strut and tie models as same as for usual R/C columns, in which the effective fiber strains of about 1% is appropriate. (3) There are few test data about the confining effect of fiber sheet wrapping on bond resistance of longitudinal bars. Further research effort is required to evaluate the shear strength of columns governed by the splitting of cover concrete along longitudinal bars. (4) The ductility ratio can be roughly estimated as a function of the shear to flexural strength ratio. (5) For the specimens with plain round longitudinal bars, the previous equations based on the strut and tie model cannot be applied because of the poor bond capacity.

This paper discusses the procedure and results from in-situ load tests performed on strengthened double tee beams in a precast parking garage. The load tests were performed to evaluate and confirm the performance of the double tees after the members had been strengthened in shear. Carbon FRP sheets were used as shear reinforcement at a 0/90° combination on the stem of each double tee. Load tests were performed on twenty double tees at various locations and floor levels of the parking structure. Each complete load test, including assembling and dismantling of the test equipment, was completed in approximately three hours. Results indicate that the shear strengthening systems increased the capacity of the double tee beams to meet the design load requirements.

In this paper the results of a series of tests, which were carried out using a total of 16 specimens of reinforced concrete (R/C) columns having wing walls retrofitted with fiber reinforced polymer (FRP) sheets as shear reinforcement, are described. In this work, the FRP sheets were adhered with epoxy resin. The specimens before retrofit were designed by the abolished Japanese seismic code before 1971. The primary test variables were the widths of the wing walls stretching from the columns, the kind of FRP sheets and its amount as shear reinforcement. It was observed that all specimens failed in a shear mode except for one specimen and that the ultimate shear strengths increased linearly in proportion to the amount of the fiber as shear reinforcement. ( i.e., the product of tensile strength and equivalent reinforcement ratio which corresponds to an replaced rectangular cross section of the column and the wing walls as a whole.) Based on the test results of regression analysis, an equation to evaluate the ultimate shear strength of R/C columns having wing walls retrofitted with FRP sheets is proposed.