Abstract. The use of non-metallic fibre reinforced polymer (FRP) reinforcement as an alternative to steel reinforcement in concrete is gaining acceptance mainly due to its high corrosion resistance. High strength-to- weight ratio, high stiffness-to-weight ratio and ease of handling and fabrication are added advantages. Other benefits are that they do not influence to magnetic fields and radio frequencies and they are thermally non- conductive. However, the stress-strain relationship for Glass FRP is linear up to rupture when the ultimate strength is reached. Unlike steel reinforcing bars, GFRPrebars do not undergo yield deformation or strain hardening before rupture. Also, GFRP reinforcement possesses a relatively low elastic modulus of elasticity compared with that of steel. As a consequence, for GFRPreinforced sections, larger deflections and crack widths are expected than the ones obtained from equivalent steel reinforced sections for the same load. This paper presents a comparison of the experimental results with those predicted by the ACI 440 code in terms of; measured cracking moment, load- deflection relationships, ultimate capacity, modes of failure, stresses and crack width. This is to investigate the suitability of using the existing ACI design equations for predicting the flexural behaviour of samples reinforced with GFRPrebars. In this investigation, it appears that the ACI code equations on the whole over predict (i.e. crack widths and midspan deflection) the experimental results. On the other hand, the maximum experimental moment satisfies the ACI condition (i.e. unfactored design moment).
comparison with steel, are a lower modulus of elasticity and a linear elastic behaviour up to rupture, which implies the lack of plasticity in the behaviour of FRP . From among research studies conducted on flexural behavior and serviceability performance of concrete beams reinforced with FRP bars one can refer to [5-15]. Among the research studies conducted on pullout behavior of GFRP bars in concrete and bond stress-slip behavior of GFRP bars in concrete respectively one can refer to  and , and Studies conducted on shear behavior of concrete beams reinforced with GFRP bars include references [18, 19]. The present study focuses on investigating the effectiveness of FRP reinforcing on the pushover behaviour of RC beams using FE modeling technique. The FE meshes, boundary conditions and nonlinearity implementation methods have been calibrated/validated by comparing the predictions of the available experimental data. Subsequently, effects from FRP reinforcing on the bending response of RC beams were studied. Moreover, two groups of FRP and steel reinforced beams, with same reinforcement ratio, have been selected to investigate the effect of FRP reinforcement on the moment capacity of RC beams. Geometrical and material nonlinearities in the concrete material, steel reinforcements and also FRP reinforcement have been taken into consideration. In the study effects from the variation of span/depth ratio, the reinforcement ratio and the effective depth of the beam are that the new issues that have been addressed.
After reaching the ultimate load, the load carrying capacity of the beam reinforced with the MMFX beam was reduced from 77.9 kip to 74.2 kips. The beam continued to resist the 74.2 kips applied load until the decision was made to unload the beam at a deflection of 2.95 inches. This was done for safety reasons and to avoid causing damage to the instrumentation. The maximum steel stress in the MMFX rebar was 140.02 ksi, which corresponded to 0.9 percent steel strain. The measured strain suggests that the MMFX rebar did not reach its maximum capacity and failure of the beam was due to the crushing of the concrete. It is reasonable to assume that the beam with MMFX reinforced steel would still be capable of achieving higher section ductility if the load had not terminated. It should be noted that prior to failure the two beams, Beam B1 and Beam B3, provide an ample warning by showing a large deflection and a series of extensive cracks.
cases steel RC structures are subjected to corrosive environments. In aggressive environments, the use of steel reinforcing bars stands out as a significant factor leading to significant limit of the life expectancy of reinforcedconcrete structures. The use of fiber reinforced polymers (FRP) reinforcement is particularly attractive for structures that operate in aggressive environments, such as in coastal regions. The magnetic transparency of FRP bars makes it a unique material that can be used to reinforce buildings that host magnetic resonance imaging (MRI) units or other equipments sensitive to electromagnetic fields. FRP composite bars in general offer many advantages over conventional steel, including one-quarter to one-fifth the density of steel, high fatigue resistance, no corrosion even in harsh chemical environments, greater tensile strength than steel, and ease of handling at job sites and cutting -. In recent years, the progressive development in FRP mechanical and physical properties has promoted the use of FRP as internal reinforcement in RC structural members. Because of the difference in mechanical and physical properties of FRP bars compared with steel bars, especially regarding the surface de- formation and the modulus of elasticity, the bond behavior of FRP reinforcedconcrete specimens is quite dif- ferent than that of steel reinforced specimens - . Whereas, the mechanical properties of the FRP bars are one of the main aspects to be considered in the design of concrete structures. Enhancing the bond of reinforcing bars is considered an efficient technique to improve the load-carrying capacity of such concrete element. Also, crack width deformability, and strength, of concrete are significantly enhanced by increasing the bond strength between concrete and FRP bars. Based on the existing experience of bond behavior of FRP bars in concrete, the primary variables which influence the bond strength are: bar type, bar diameter, shape of cross section, surface characteristics, embedment length, strength and cover of bonding agent, and temperature . Although, exten- sive studies were conducted to study concreteflexural elements reinforced with circular cross-section FRP bars    -, up to date, there is a scarcity of data available from effect of bar shape, particularly square cross- section. In this paper, the behavior of RC slab reinforced with newly develop GFRP square cross-section bar conducted to provide additional understanding regarding the serviceability and flexural behavior as a result of change of bond properties using GFRP square bars.
The tensile strength capacity of ordinary concrete is small when compared to its compressive strength capacity. This will have an undesirable impact on the ordinary concreteperformance as an important building and construction material. As a result, it became necessary to use steel reinforcement and sometimes huge section members which are aesthetically unfavorable and consume large amounts of materials. Reactive Powder Concrete (RPC) is an emerging technology that has the ability to overcome the aforementioned drawbacks and enhance the concrete mechanical properties. RPC is usually formed from extremely fine powder materials (cement, sand, quartz powder and silica fume), steel fibres (optional) and superplasticizer . M. M. Kadhum in 2014  indicated that RPC can be produced with acceptable mechanical properties using local fine sand instead of quartz powder.
Abstract: Conservation of natural resources and protection of environment is the key to sustainable development. The investigation on flexural behaviour of recycled aggregate concrete (RAC) slabs presented here is one such attempt to establish performance of recycle aggregate concrete as structural grade concrete. The Experimental investigation examine the crack width and strains of rectangular one way simply supported steel reinforcedconcreteslabs by using natural and recycled coarse aggregate under simulated uniform loading. The reinforcedconcrete (RC) slab specimens of size 1300×600×90mm were cast. The experimental programme consisted of casting and testing of twelve slabs. Out of 12 slabs, ‘6’ slabs were cast using natural coarse aggregate and another ‘6’ slabs were cast using 50% replacement of NCA by RCA. Again in each ‘6’ slabs, ‘3’ slabs were cast with 8mm dia reinforcement bars and the other ‘3’ slabs were cast with 6 mm dia reinforcement bars. M20 grade of concrete with various percentages of steel such as 0.30%, 0.40% and 0.50% were cast. All the twelve slabs were 90mm thick. These slabs were subjected to uniformly distributed loads. The investigations indicated encouraging results for RAC slabs in all respects, thus, pointing to recycled aggregate as potential alternative source of aggregate of the 21 st Century. Finally a comparison is made between experimental results and theoretical predictions of the same and among specimens made with 6mm rebar and 8mm rebar.
3 which makes them suitable for use in the alkaline concrete surrounding (Burgoyne et al., 2007; Parnas et al., 2007; Adhikari, 2009). On the other hand, BFRP bars are characterized by their lower cost and superior chemical resistance than their GFRP counterparts (El Refai, 2013; El Refai et al., 2014b; Elgabbas et al., 2015). Furthermore, sand-coated BFRP bars showed higher bond strength and higher adhesion to concrete than ribbed GFRP bars (Altalmas et al., 2015). It is important to note that few studies have recently focused on the use of BFRP bars as internal reinforcement. Therefore, codes and standards authorities are yet to formulate equations for the design and analysis of concrete elements internally-reinforced with BFRP bars. To the author’s knowledge, no studies have been performed to investigate the structural response of continuous concrete structures internally-reinforced with hybrid steel-BFRP bars.
Concrete is a versatile construction material used global. Concrete technologists are constantly carrying out the research to beautify the overall performance of concrete to satisfy the beneficial, energy and sturdiness requirement. Concrete has the downside of being weak in anxiety, porous and prone for environmental attack. The problems of simple concrete were overcome is happy, via including fibre to decorate density for better overall performance. The necessity for new non corrosive material because of corrosion problems associated with metal.
563 | P a g e Extensive researches are going on in the areas of application of FRP in concrete structures for its effectiveness in enhancing structural performance both in terms of strength and ductility. Retrofitting with fiber-reinforced polymers (FRP) may provide technically superior alternative to the traditional techniques in many situations. The FRPs are lighter, more durable and have higher strength-to-weight ratios than traditional reinforcing materials such as steel, and can result in less labor-intensive and less equipment-intensive retrofitting work. Structures were originally designed according to earlier codes to withstand only gravity loads and the impacts of earthquake are not considered. Even if it was considered the collapse might be due to the change in hazard level in that region. The use of fiber-reinforced polymers (FRP) composite materials for strengthening/ retrofitting of existing structure has increased in recent years. The FRP products can be used for structural strengthening/ retrofitting of existing building and bridges and for construction. Strengthening/ retrofitting is required when there are increases in the applied loads, human errors in initial construction, accident event such as earthquakes and when a structural member losses its strength due to deterioration over time. The cost associated with replacing the structure back in service immediately is relatively high that strengthening/ retrofitting become the most efficient solution. There are different available materials like FRP, steel, concrete etc. for retrofitting of the structure, but use of FRP is increasing rapidly. This is due to the fact that FRP materials have several advantages over steel and other materials. They are lightweight with superior strength and stiffness-to-weight ratio, they have relatively high corrosion resistance, and FRP laminates can be easily bonded to concrete surfaces. Typical uses of FRP in construction are as follows:
fraction (0%, 0.5%, 1% and 2%). The deflection, compressive concrete strain at mid-span of the one-way slab were measured and recorded. The testing results were compared with control specimens reinforced by GFRP reinforcing bars and with no added BMF. The testing results of the specimens were compared to the analytical equation for deflection’s prediction. Experimental and numerical results showed a general improvement in the flexural behavior of concrete one-way slabs by adding more BMF and increasing the reinforcement ratio. On the other hand, there were no major differences between BFRP and GFRP reinforcing bars. The main difference between them was because of the surface of FRP reinforcing bars. The ribbed surface of GFRP reinforcing bars gives better flexure for concrete one-way slabs than the sand coated surface of BFRP reinforcing bars, especially in over-reinforced samples. Test results clearly showed that both FRP reinforcing bars and BMF can be used as alternative materials for steel reinforcement in concrete structures. 6.2 CONCLUSION
73% of the total failure loads of beams C-G-1 and C-H-1, respectively. This comparison between the failure loads of the simply supported beams S-G-1 and S-H-2; and that of the continuous hybrid C-G-1 and C-H-1 beams is due to the fact that each compared set of beams were reinforced with the same area of reinforcement. In comparison with beam C-H-1, beam C-H-5 that was reinforced with higher reinforcement ratio of GFRP bars tolerated more loads than beam C-H-3 that was reinforced with higher reinforcement of steel bars. This is attributed to the fact that GFRP bars play an important role to resist loading after yielding of steel reinforcement. In addition, the high compressive strength of beam C-H-5 contributed in load capacity increase. It also shows that load capacity increase is not dependent on the axial stiffness as the axial stiffness of C-H-3 is much higher than that of beam C-H-5. The results show that the load capacities of hybrid reinforcedconcrete continuous beams C-H- 2, C-H-3, C-H-4 and C-H-5 were, respectively, around 1.2, 1.26, 1.4 and 1.7 times that of the control beam C-H-1. This confirms that GFRP reinforcement is mainly responsible for enhancement of load capacity. Although the steel reinforcement ratio used to reinforce the critical sections of beam C-S-1 had similar strength of that used in beam C-G-1, beam C-S-1 exhibited a higher load capacity than that of beam reinforced with pure GFRP bars due to the large deformation resulting from the lower modulus of elasticity of GFRP.
GFRP is a composite and anisotropic material containing fibre impregnated within a polymeric matrix. The non-corrosive property of GFRP is the main reason for using GFRP rather than steel as a reinforcement in concrete structures (Deepa et al., 2016, Manalo et al., 2014). GFRP also has a higher tensile strength-to-weight ratio, a higher fatigue resistance, and better thermal and electrical insulation (Robert et al., 2009). In 2012, (Chang and Seo, 2012) experimentally investigated the flexural behaviour of one-way solid slabsreinforced with GFRP bars and compared them to steel reinforcedslabs. They showed that GFRPreinforcedslabs performed better and had a longer fatigue than steel reinforcedslabs because the modulus of elasticity of GFRP reinforcements is closer to the modulus of elasticity of concrete than steel. Furthermore, (Gu et al., 2016) concluded that a greater amount of GFRP reinforcement in a concrete beam will result in smaller deflection and narrower cracks. Moreover, (Chang and Seo, 2012) indicated that the slip of reinforcement in concrete was smaller in FRP bars than steel due to the lower modulus of elasticity of the former. The bond between GFRP bars and concrete is now better because many manufacturers are providing sand particles around the surface of the GFRP bars e (Okelo and Yuan, 2005); this developments has resulted in GFRP bars being widely used in structural designs (Robert et al., 2009).
Fibre reinforced polymer (FRP) composite materials in the constructing of new structures and retrofitting of the existing structures is a novel invention that can replace the conventional steel bars and plates because FRP materials can eliminate the corrosion problem. Corrosion is a considerable issue in the humid, aggressive, and coastal areas that causes large maintenance cost and sometimes the structure loses its performance 1 . In general, FRP composite is produced in Glass (G), Carbon (C) and Aramid (A) fibre, while the glass fibre is most familiar to produce FRP bars because glass fibre is cheaper than carbon fibre and its characteristics is better than aramid fibre. However, the mechanical properties of GFRP bars are different than steel bars because GFRP bars have higher tensile strength to weight ratio and their modulus of elasticity is about a quarter of the steel bars. The behaviour of GFRP bars under compression is complex because some different parameters such as debonding or buckling of the fibres can play roles. Therefore, to figure out the behaviour and the effect of GFRP bars on the ReinforcedConcrete (RC) columns and the lack of experimental studies in this field, 18 circular concrete columns were cast and reinforced with conventional steel and GFRP bars and helices. Four of the specimens were confined externally with CFRP sheets. The specimens were tested under concentric, eccentric and flexural loading in this study.
Hence in line with current trend of using a structural system which brings economic feasibility, speed and versatility of application, the use of waffle slab is becoming an attractive structural solution. This structural system can be defined as the constructions having a system of a flat flange plate, or deck, and equally spaced parallel beams, or grillage, that may be arranged in either an orthogonal or non-orthogonal assembly with monolithic intersections . They are also known as two-way ribbed flat slab and being used increasingly in modern construction to reduce dead weight. The system exhibits higher stiffness and smaller defections. However, the most common types have large square voids or recesses between the ribs. Not only the normal reinforcedconcrete waffled slab has benefits over the normal reinforced solid flat plate, but also a pre- stressed waffle-type bridge is found to be much more efficient in carrying load than a pre-stressed bridge with constant thickness slab as presented by Kennedy . Kennedy  studied the effect of orientation of rib in the load carrying capacity of waffled slab. His results indicated that the orthogonal shaped waffle slab has a superior ultimate load carrying capacity of 20% higher than the non- orthogonal (45°) waffle slab. Abdul-Wahab and Khalil  investigated experimentally the response of simply supported, isotropically reinforced, square waffle slabs under a midpoint patch load.
Basically there are two types of techniques used i.e. seismic resistance based design and Seismic response control design. In former we use Concrete jacketing, Steel jacketing and GFRP wrapping whereas in latter we uses Elastic-plastic, dampers Base isolators and Tuned liquid dampers and many other options are possible. For long time we have been using methods such as addition of shear walls, infill walls, buttresses, etc but with
obtain the expected life span of structures. Strengthening of RC beams using steel plates and FRP composites are most common globally. In order to minimize the disadvantages of steel , many researchers have tried various FRP composites such as Aramid, Glass and Carbon. Advantages given by this material is such as resistance against corrosion, high tensile strength, superior ductility, light weight, and absence of heavy additional equipment in application. Strengthening the structural members of old buildings using advanced materials is a contemporary research in the field of repairs and rehabilitation. The strengthening of the beams is done with different amount and configuration of GFRP sheets. This investigation deals with experimental study of retrofitted reinforcedconcrete beams using Glass Fiber Reinforced Polymer (GFRP). The effect of number of GFRP layers and its orientation on ultimate load carrying capacity and failure mode of the beams are investigated. Rectangular corrugated GFRP laminates are used for strengthening RC beams to achieve higher flexural strength and load carrying capacity.
Regarding difficulties, design in ultimate limit state has shown that a reduction of ordinary reinforcement and addition of fibres, for the fibre amounts used in this project, was far from enough. Design of elements without ordinary reinforcement proved that very large amounts of fibres are needed in order to compensate for the absence of ordinary reinforcement. According to Bentur and Mindess, the amount of fibres that can be applied using the premix method is limited to 2% which is in this evaluation not sufficient enough to partly or entirely replace ordinary reinforcement. Another difficulty is in the design of fibre reinforcedconcrete elements without ordinary reinforcement, where the design of shear resistance and crack width require further attention as no design suggestions are yet proposed.