In this study, the use of precast laminates, made of high-performance fiber-reinforced cementitious composite (HPFRCC), was investigated for strengthening of continuous reinforced concrete (RC) beams. HPFRCCs are characterized by their high tensile strength and remarkable durability properties. To find the effect of strengthening, eight continuous (two-bay) RC beams were tested under monotonic load in the middle of spans,two of which were the control specimens and six of which were strengthened specimens. The HPFRCC laminates were prefabricated with 25 mm thickness and bonded to the tensile surface of beams using epoxy and mechanical anchorage. The longitudinal bars were added to laminates in four specimens to survey their effect on strengthened beams. Comparison of results declared that the load carrying capacity was increased up to 59 % in strengthened beams. Ductility index of the strengthened beams was acceptable, and also up to 35 % growth in energy-absorption capacity was observed. Applying laminates to the tensile surface delayed crack propagation and decreased the midspan deflection. Also, stiffness of specimens in the cracked concrete stage was increased up to 78 % that led to decrease the service deflection. It is concluded that the use of HPFRCC laminates, especially in case of applying longitudinal bars, is an efficient method to enhance the flexural capacity of continuous RC beams.

Externally Bonded Reinforcement (EBR) is the most common technique used to strengthen the RC members with carbon fiber reinforced polymer (CFRP) sheets. Recently, a new proposed technique was named Externally Bonded Reinforcement on Grooves (EBROG) has been presented as an alternative method to avoid or eliminate the undesirable de-bonging failure mode that is accompanying to EBR method. This paper is devoted to investigating the effect of the strengthening techniques on the flexural behavior of RC continuous beams externally strengthened with CFRP sheets in both hogging and sagging zones, by testing twelve beam specimens. All beams have the same cross-section (200×130) mm and 2300 mm length. The parameters of this study include strengthening methods, length and layers number of CFRP sheet and number, length and direction of grooves, in addition to the effect of presence of steel fiber in the hogging zone. The results are introduced in terms of ultimate load, ultimate deflection, ductility index and mode of failure. The test results showed that the EBROG strengthening method has highly effective in improving the ultimate load of strengthened beams. The specimens strengthened by one and two layers of CFRP using EBROG with three longitudinal grooves have a rising in the ultimate load by about (24.4 and 52.6) % respectively, in comparison with the same beams but strengthened by EBR. Also, the mode of failure was changed from CFRP debonding in case of EBR beams to CFRP rupture, or to concrete cover separation in EBROG beams. Finally, the strengthened beams with CFRP sheets presented a more brittle behavior at failure than the unstrengthening specimen.

Studies have shown that one of the leading causes of earthquake inflicting irreparable damage has been the high weight of structures. Using FRP composite sheets-due to the proper mechanical and physical properties to reinforce and improve concrete members in load-bearing, removal of concrete in the deflection and increasing the ductility of concrete-is an appropriate option. The purpose of this study is to strengthen voided concrete slabs with AFRP, CFRP and GFRP. In this study, 10 specimens of reinforced concrete with dimensions of 150×70×20 cm were investigated. The results demonstrated that the amount of load capacity in the Network strengthened specimen with CFRP compare to the control sample 175% and, in Linear, strengthened specimen with AFRP in comparison with the control sample 153% increased. This value in comparison with Solid specimens increased by about 96% for samples having been strengthened with CFRP and 91% for those strengthened with AFRP. The maximum displacements have been presented in the specimen strengthened with CFRP (236%) compared to that of the control sample and in the specimen strengthened with GFRP (99%) compared to that of the control sample. The stiffness amounts in Linear specimen strengthened with CFRP 225% compared to that of the control sample and in Network specimen strengthened with AFRP 136% compared to the that of control sample also increased.

An experimental study on the flexural behavior of reinforced concrete (RC) arches strengthened with glass fiber-reinforced polymer (GFRP) layers is performed. Totally, 36 specimens including 3 un-strengthened (control) and 33 strengthened RC arches were tested under centrally concentrated point load. The variables of this study were the steel reinforcement ratios, number of GFRP layers, and location and arrangement of GFRP layers. The failure mode, load-displacement response of specimens, crack propagation patterns, and GFRP debonding were examined. The extrados strengthening method was more effective than intrados strengthening approach in improving the failure load and rigidity of the arches. However, applying excessive GFRP layers at extrados can change the failure mode of arches from flexural to shear failure. The dominant failure mode of specimens was flexural and ductile failure due to the formation of five-hinge mechanism. Generally, GFRP strengthening could augment the ultimate load carrying capacity, secant stiffness, and energy absorption capacity of arch specimens by up to about 154, 300, and 93 percent, respectively. Statistical analyses were performed to assess the level of influence of each considered parameters on the behavior of RC arches. Finally, Analytical approach predicts the experimental data on arches with five-hinge failure mechanism satisfactorily.

The effectiveness of FRP jackets for increasing the compression strength, shear strength and ductility of reinforced concrete (RC) columns was demonstrated in many studies, but the influence of FRP jacketing on the flexural capacity of columns is minimal. In this paper, a new retrofit method, which utilized near surface mounted (NSM) fiber reinforced polymer (FRP), was studied aiming to improve the flexural capacity of RC columns subjected to bending and compression. This technique is based on bonding fiber reinforced polymer (FRP) bars into grooves cut in the cover of RC columns. For this purpose, five reinforced concrete column specimens were designed, constructed and subjected to constant axial compression and lateral cyclic loading. In addition, the strengthened columns were wrapped with carbon composites to satisfy seismic detailing requirements. The test results show that by using the NSM technique, the flexural strength and lateral load capacity of the columns increase significantly. The test results were also compared with the results obtained from the analytical study that was conducted based on strain compatibility.A good agreement between analytical and experimental results was observed.

Shear wall has been widely used in RC structures due to its high initial Stiffness and lateral load capacity. Hence, the behavior and effectiveness of retrofitting technique on shear wall are needed to be investigated widely. In this paper, a numerical analysis was performed using LS-DYNA finite element program to predict the behavior of squat RC shear wall strengthened by fiber reinforced polymer in flexure. The strengthening scheme was conducted by externally bonding vertical layers of FRP on each side of the wall and anchoring them at the wall base with a structural steel angle bolted to the support. Numerical results were validated against experimental data. Then, the influences of number of FRP layers, anchorage system, percentage of horizontal web reinforcement, percentage of vertical web reinforcement and percentage of vertical reinforcement in the boundary element were investigated. The results showed that the scheme can significantly improve the behavior of the RC shear wall. In addition, the behavior of strengthened wall and strengthening scheme strongly depend on the amount of web reinforcement which can also change the failure mode.

Several full porcelain systems are available in the market, among which In - Ceram (Vita Zahnfabrik, Bad Sackingen, Germany), has been introduced to show unique properties including: fine esthetic and high quality strength. In this investigation flexural Strength of In - Ceram core material has been evaluated by four - point bending test with Instron (Model 1195) machine. Samples were provided in form of ten bars of core material with the dimension of 30 × 6 × 2.5 mm.Results obtained show that the mean value of 538 ± 42 (MPa), of force is required to hit its resistance limit which is higher than similar values in other dental ceramics, within acceptable clinical range.

One of the common techniques for enhancing the strength of existing reinforced concrete bridge beams involves adding reinforcing elements to the lower section of the beam. In the recent years, the reinforcement of concrete bridge beams is developing with the installation of precast high performance fiber reinforced cement composites, in addition to Fiber-Reinforced Polymer (FRP) sheets or strips and placed rebars near the surface. This study explores both the mechanical properties of composite cement laminates and how the presence of polymer rebars impacts these laminates. To create specimens, a total of 45 mixing designs were utilized, incorporating fibers and consumable materials. For comparison purposes, the specimens underwent various tests including four-point bending test with dimensions measuring 25×125×500 and 25×125×1700 mm, three-point bending test with dimensions measuring 40×40×160 mm, direct tension test on 8 shaped briquettes and compressive strength tests on cubic shapes measuring 40 mm. The results indicated good compliance with both direct tension and bending tests. After evaluation, the most suitable design was determined to consist of 1.8% micro steel fibers, 0.5% polyvinyl alcohol fibers, 42 kilograms of quartz powder, 28.6 kilograms calcium carbonate particles and 482 kilograms of silica fume slurry, per cubic meter of mortar. To analyze the chosen specimen, we conducted direct tension test on dogbone-shaped specimen and compressive strength test on cubic specimen measuring 100 millimeters. Adding quartz powder has a positive impact on enhancing the energy absorption capability of the laminate specimens. The use of two polymer rebars with a diameter of 8 millimeters lead to 2.3 times increase in the flexural stress tolerance. No significant difference was observed between the flexural behavior of the precast laminate under cyclic loading and the monotonic loading.

Assessment of the effectiveness of ferrocement strengthening techniques i.e., cast in situ Ferro-mesh layers and precast ferrocement Laminate is the aim of this experimental investigation. To accomplish this objective, ten (10) reinforced concrete beams including one control beam have been intentionally designed and detailed to fail in flexure. Prior to strengthening, beams have been tested under two-point loading till service limit. Beams have been strengthened in the flexural dominant region only and tested to failure under the same loading arrangement. It has been concluded that strengthening through cast in situ Ferro-mesh layer is the most efficient technique, whereas strengthening of the beams by using precast Ferrocement Laminate B is not only easy to implement at household level, but is also promising in terms of enhancing load carrying capacity, stiffness and ductility.

Many reinforced concrete buildings in the world and Iran, have a life of over several decades And many reasons have been damaged. According to the Replacing these buildings will lead to high costs and is no economic and Environmental feasibility and Due to the need Increasing engineers and construction industry Professionals to strengthen, repair and rehabilitation of concrete structures, Several different methods have been proposed for this issue. One method of strengthening is the approach of using a special concrete With high capabilities. one of these concretes is HPFRCC. Experimental Studies have been carried lately about strengthening with HPFRCC on beams, Columns, slabs and other Structural elements and the strength of this concrete Has been confirmed in strengthening. High performance fiber reinforced cement composite (HPFRCC) is a material that is composed of a cement-based matrix and short composite and steel fibers. that Indicate multiple cracking under tensile stress and because of high bonding strength, HPFRCC used as a repair material. However, the mechanical performance of a RC member repaired with HPFRCC has yet been investigated sufficiently. In this paper, is used layers of HPFRCC (HPFR CC patching) in different thickness for deficient RC slabs flexural Strengthened and numerical Study HPFRCC layers on this slabs with Finite Element.