Fiber-reinforced polymer (FRP) anchors are used to prevent or delay the debonding of FRP sheets in the strengthening of structures. There are various methods to prevent or delay the debonding of FRP sheets, among them is the use of FRP anchors. In this research, the behavior of the bond between the FRP sheet and the FRP anchor after the debonding of the reinforcement sheet from the concrete surface was evaluated. Therefore, the specimens were reinforced in such a way that there is no bond between the reinforcement sheet and the concrete surface. The simultaneous increase in the ratio of the cross-sectional area and the length of the fan leads to an increase in the bond strength; therefore, the specimens with a fan length of 90 mm experience an average increase of 50% in bond strength. In this case, the failure mode was anchor debonding from the sheet. Results showed that increasing the length of the fan improved the bond strength. Therefore, the specimens with a fan length of 150 mm reached the bond strength to almost the ultimate tensile strength of the FRP composite. The amount of slip, in this case, is on average 2.5 times the specimens with a 60 mm length of fan. According to the failure mode of the specimens, the embedment depth of 50 mm has the ability to fully transfer the stress to the concrete and the anchor has not been pulled out.

In this research, using the nonlinear finite element method, a numerical study has been performed on the seismic behavior of the deficient RC beam-column joints (with non-seismic detailing), and the seismic rehabilitation of these joints by using FRP composite laminates. At first, based on previous experimental studies, a series of RC joint specimens were considered to verify the proposed numerical model. This series of specimens include six RC interior joint specimens with non-seismic detailing and retrofitted with FRP laminates under cyclic loading. Comparison between the load-displacement curves obtained from the numerical model with corresponding experimental data shows that the proposed model is capable to high accurately predict the response of RC joints under cyclic loading. Then, based on the verified model, the performance of two-dimensional (2-D) deficient and strengthened exterior RC joint, three-dimensional (3-D) interior and exterior RC joints with considering the effect of the slab and beam perpendicular to the plane of the frame and also strengthening of (3-D) RC joints with focusing on the behavior of the FRP to the concrete interface is evaluated. It was observed that the failure mode of the retrofitted RC exterior specimens, unlike the deficient specimens, is the formation of the plastic hinge in the beam section. In addition, it is seen that the slab and the lateral beam have a significant effect on the performance of deficient joints, which can increase the resistance of the 3-D specimens by more than 20%; also, in 3D strengthened joints, the possibility of debonding of FRP laminates from concrete is higher than the 2-D model.

Background and Aims: Micro leakage is a criterion proposed for assessing the success of any restorative material. Complete seal is difficult especially for dentin margins compared to enamel margins. The aim of this study was to assess the micro leakage at the enamel and dentin margins of class V cavities restored by two GIs and two self-etch adhesive systems.Materials and Methods: This study was done on forty third molars. Class V cavities (3´2´2mm) were prepared on the buccal and lingual surfaces of teeth using high speed handpiece with 0.8 mm diamond fissure burr. The occlusal margins of the cavities in the enamel and gingival margins were placed 1 mm below the CEJ. The teeth were divided into 4 groups and the bondings were cured for 20 sec and the teeth were restored. The specimens were kept in distilled water at the temperature of 37°C for 24 hrs. The teeth were thermo cycled and cut in buccolingual direction using diamond disc under water. The dye penetration was evaluated using a stereomicroscope and the leakage was scored. The scores were compared using Kruskal-Wallis test while the paired comparisons were done using Bonferroni correction. P≤0.05 was regarded as significant results.Results: Micro leakage scores were similar at the occlusal and gingival walls of all test groups. At the gingival walls, the least micro leakage scores were observed. “Fuji IX + SE bond” group showed significant differences with the “Fuji IX + G bond” and “Nano GLASS + G bond” groups (P£0.05). At the occlusal walls, the least scores were observed in the “Fuji IX+SE bond” specimens which were significantly different from the other groups (P£0.05).Conclusion: Self-Cure GLASS ionomers yielded less micro leakage scores compared to the different types of light-cures due to the less polymerization shrinkage.

Fiber-reinforced polymer (FRP) wrapping of reinforced concrete (RC) columns is an effective way to improve their shear capacity and ductility and prevent buckling in their longitudinal reinforcements. Another strengthening method called the near surface mounted (NSM) reinforcement has been proven effective in improving the flexural strength of RC columns. In this research, the strengthening of RC columns with the combined use of NSM rebars and FRP jacket was studied using a finite element modeling approach. After validating the numerical models with the existing experimental data, a comprehensive parametric study was performed to determine the effect of axial load, implementing the FRP confinement around the base or over the entire height of the column, the number of plies of FRP jacket, the type of jacket fiber, the ratio of NSM reinforcement, and the compressive strength of the concrete on the behavior of the strengthened RC columns. The results show that the optimum number of plies of jacket for reaching a desirable level of ductility can be determined by setting the maximum compressive strain in the confined concrete,  ccu, to 0. 008. Increasing the ratio of NSM reinforcement from 0. 16% of the total cross-sectional area to 1% led to approximately 28% increase in the lateral strength and 50% decrease in the ductility factor.

Concrete shear walls are one of the main lateral resisting members in buildings. The functional requirements like architectural and even mechanical requirements entail that openings have to be installed in structural walls as well as floors. In this study, nonlinear static analysis was utilized to study the effects of fiber reinforced plastic (FRP) on the ultimate load capacity of concrete shear walls with openings using the finite element analysis software ABAQUS. In order to verify the accuracy of the numerical model, a comparison was done between the results of experimental and numerical analysis of a concrete shear wall. Subsequent to verification of the Finite Element Model (FEM), the effects of creating cut-off openings as well as strengthening effects of applying FRP have been studied. Whereas the numerical results show good correlation between the FEM and the experimental results of reinforced concrete (RC) shear walls, the numerical analysis represents a remarkable improvement in ultimate lateral load capacity of shear wall with opening strengthened using fiber reinforced plastic. The results obtained are presented in relative diagrams and tables.

Wood is one of the oldest materials that has always been known as a construction material. Despite its widespread application and unique properties, it has weaknesses such as relatively brittle behavior, especially in bending. In order to improve its performance and boost its features or strengthen wooden structural members, one solution is to employ FRP component, which is widely used as a rehabilitation tool. The lightness and ease of application for different materials such as concrete, wood, and steel have made it possible to increase the strength and ductility of structural elements. In this study, the few models that were available for the wood-FRP system were collected, and the uncertainty of six variables, as the most effective parameters in the strength of this system, was selected for reliability analysis. Also, during the steps, three live to dead load ratios equal to 0.75, 1, and 1.25 were assumed as the design loads. What was achieved during this research was that during the design process of wood-FRP, uncertainties had a significant impact on the reliability of existing models. Some models could be reliable enough to be applied for design purposes; however, uncertainties seriously affect the reliability of some models. Accordingly, the average reliability index of all six available models decreased from 4.88 in case one fails to consider uncertainties to 2.71 with uncertainties of the models. Among the five existing models presented in previous studies, the Palizi and Toufigh model with an average reliability index of 3.61 was the best-proposed model, which is in good agreement with the acceptable index of existing structural design criteria. It is worth noting that various variables affect the reliability of this system. However, in this study, only the uncertainty of the six variables of modulus of elasticity, thickness, length, and width of FRP, along with wood width and its compressive strength, was considered. Other sources of uncertainties may be considered while analyzing this system in future studies.

This paper presents the structural behavior of reinforced concrete beams with surface mounted GFRP and hybrid FRP laminates under static loading condition. A total of seven beams were cast and tested under four-point bending. One beam without FRP served as the control beam, two beams were strengthened using GLASS fibre reinforced polymer laminates (GFRP) and four beams were strengthened using hybrid FRP (carbon+GLASS) laminates in flexure. From the experimental study, it was observed that strengthening of RC beams with hybrid FRP laminates resulted in increased load carrying capacity, reduced deformations, enhanced ductility and energy absorption. The load carrying capacity of the test beams was predicted using ACI 440.2R-08 guidelines. The experimental and predicted results are in good agreement.

In this study, FRP effects on cyclic and push over behavior of locally and globally rehabilitated concrete frames were investigated. ABAQUS software used for modeling of frames. At first a 3 story-2 bay concrete building was modeled under gravity and earthquake loadings and then one of its frames was chosen as the base frame of this research. In the second step the base frame was weaken and rehabilitation carried out using three kinds of FRP named carbon, GLASS and aramid to compensate the lack of capacity. Strengthening of frames was done in two types of local and global manner and in each type three kinds of FRP were used. Force-displacement curve and stress-strain counter were determined for all of the models. Results showed positive effects of FRP using in rehabilitation of concrete frames. In local rehabilitation, all FRP improved the both of loading capacity and ductility but carbon FRP compensated all lack of capacity that was imposed to the model. In global rehabilitation, all kinds of FRPs showed satisfying performance in improving capacity of concrete frames. At the end, local strengthening by carbon FRP was showed the best performance among the others and GLASS FRP was presented the optimum behavior in global strengthening.