Current design methods for predicting deflections and crack widths at service load in concrete structures reinforced with steel bars may not be necessarily applicable in those reinforced with fiber reinforced polymer (FRP) bars. In this paper, methods for predicting deflections and crack widths and spacing of glass fiber reinforced polymer (GFRP) reinforced concrete beams were proposed. In order to use the effective moment of inertia for concrete beams reinforced with FRP bars, the effect of reinforcement ratios and elastic modulus of the FRP reinforcement were incorporated in Branson’s equation. This paper also presents a new equation to predict crack width. Six concrete beams reinforced with different GFRP reinforcement ratios were tested. Deflections and crack widths were measured and compared with those obtained by the proposed models. The comparison between the experimental results and those predicted was in good agreement.

Many pretensioning prestressed concrete (PC) beams using the grid glass fiber reinforced polymer (GFRP) reinforcements as prestressing tendons were manufactured. The initial prestressing forces were selected at various levels, namely from 0 to 52.5 % of the tensile capacity of the grid GFRP reinforcement. Then, the PC beams were left outdoors for a long time, namely from seven to eight years. Thereafter, they were demolished to take the grid GFRP reinforcements out. First, the tests on tensile properties of the grid GFRP reinforcements were carried out. Their residual tensile capacities decreased only a little, and moreover, their residual tensile rigidities did not change. Then, the cross sections of the glass fibers of the grid GFRP reinforcements were observed with a scanning electron microscope (SEM). The cross sections remained real circular and the glass fibers were not attacked by alkali of concrete.

A study was undertaken to examine the general behaviour of reinforced concrete beams confined with carbon-fibre-reinforced polymer (CFRP) laminates subjected to accelerated rebar corrosion. Eight small-scale RC beam specimens, 1200 mm long with cross-sectional area of 100 mm by 150 mm, were constructed. Five specimens were strengthened with CFRP laminates using three different strengthening schemes. The tensile reinforcement, 2-10M bars, of six specimens was corroded to 10% mass loss by means of an impressed current. Strain gauges were placed on the CFRP laminates to monitor and quantify tensile strains induced by the corrosion process. The CFRP laminates successfully confined the corrosion cracking, and total expansion of the laminate exhibited a fairly linear and continuous increase throughout the corrosion process.

The effect of FRP material properties on the long-term deflection of concrete beams reinforced with FRP rods was investigated by the experiment of 17 beams reinforced by nine types of FRP rods and a beam reinforced by steel bars. Test results showed that the flexural stiffness of a cracked beam decreased rapidly with a reduction in tensile stiffness of the reinforcing rods. Compared to the short-term deflection of beams, the long-term deflection of the FRP reinforced concrete beams at one week after loading increased on average by 17 percent, and 57 percent at 10 months. The material properties of FRP rods had a great effect on the long-term deflection of beams. The long-term deflection increase of beams with GFRP was the smallest among all of the tested beams, and oppositely, the deflection increase of beams with AFRP was greater than the average. The rate of increase in deflection of the beams reinforced with braided rods was about 10 percent smaller than that of beams with spiral rods. Contrasting, the rate of deflection increase of beams with ribbed rods was about 10 percent greater than that of beams with spiral rods.

With their strength and their specific stiffness, composite materials present a significant interest in the conception of bearing structures. The influence of combined effects "time-temperature-loading" on composite reinforcement adhesive layer was studied to identify the long-term mechanical behavior of RC beam reinforced with FRP. A set of tests were conducted on reinforced concrete structures with carbon epoxy composites. The tests consist of applying a tensile shear stress during six months to obtain the long-term creep data and to carry out thermo-stimulated test to assess short-term creep data. The master curves set up with this method predicts with reasonable accuracy the long-term creep test data. The time-temperature superposition method is used to determine several master curves with several levels of shear stress. This method permits an evaluation of the long-term shear stress to apply in the adhesive layer to minimize the creep. The durability of repaired or reinforced structure depends on the adhesive behavior. We have assessed that the identification of the long-term creep can be done with a thermo-stimulated test. This test allows setting up the safety factor for any polymer to guaranty the structure durability.