The capacity provisions of conventional Reinforced Concrete (RC) and Prestressed Concrete (PC) beams subjected to combined action of torsion, shear and flexure are well known and stated by international/national codes. Similar provisions lack for concrete members containing Fibre Reinforced Polymer (FRP) reinforcements. In general, there is paucity of research on the treatment of torsion combined with other stress resultants for FRP-RC/PCmembers. In this paper, the theoretical method pro- posed by the Canadian standard CSA S806 for FRP-RC/PC structures is presented. The critical issues, related to this topic, such as the appropriate strength and inclina- tion of the diagonal struts and failure criteria are critically analyzed and addressed. In order to assess the reliability of this study a comparison between available exper- imental data regarding FRP-RC/PC beams subjected to combinedactions and their corresponding theoretical provisions derived by the CSA S806 standard is shown. Furthermore, another approach, available in literature, which is based on the space truss model, is examined and used for comparison in order to evaluate the theoretical provisions offered by this model against the tests value of the set of the beams ana- lyzed in this study. Based on the critical analysis of the results, it can be highlighted that the CSA method is able to conservatively predict the capacity of these beams.
1969 | P a g e member can increase by using this technique. To eliminate these problems, steel plate was replaced by corrosion resistant and light-weight FRP Composite plates. FRPCs help to increase strength and ductility without excessive increase in stiffness. Further, such material could be designed to meet specific requirements by adjusting placement of fibres. So concrete members can now be easily and effectively strengthened using externally bonded FRP composites. By wrapping FRP sheets, retrofitting of concrete structures provide a more economical and technically superior alternative to the traditional techniques in many situations because it offers high strength, low weight, corrosion resistance, high fatigue resistance, easy and rapid installation and minimal change in structural geometry. FRP systems can also be used in areas with limited access where traditional techniques would be impractical. However, due to lack of the proper knowledge on structural behavior of concrete structures, the use of these materials for retrofitting the existing concrete structures cannot reach up to the expectation. Successful retrofitting of concrete structures with FRP needs a thorough knowledge on the subject and available user-friendly technologies/ unique guidelines .Beams are the critical structural memberssubjected to bending, torsion and shear in all type of structures. Similarly, columns are also used as various important elements subjected to axial load combined with/without bending and are used in all type of structures .Therefore, extensive research works are being carried out throughout world on retrofitting of concrete beams and columns with externally bonded FRP composites. Several investigators took up concrete beams and columns retrofitted with carbon fibre reinforced polymer (CFRP)/ glass fibre reinforced polymer (GFRP) composites in order to study the enhancement of strength and ductility, durability, effect of confinement, preparation of design guidelines and experimental investigations of these members.
Strengthened beams under combined shear and torsion were rst studied by Deifalla and Ghobarah in 2010 . In their study, they tested six half- scale T-shaped beams. From among these, two were used as control and four were strengthened for the experiment. The strengthened beams were loaded under just one eccentricity (the ratio of torsion to shear (e = T=V )) for which evidently no interaction curves could be plotted. These researchers also derived an analytical algorithm based on the compression eld theory which could also be used to study beams under combined shear and torsion. However, to the best of our knowledge, no study seems to have been reported in the literature on FRP-strengthened beams under combined shear and torsion. Knowledge about this behavior becomes signicant in designing reinforced concrete members strengthened with FRP sheets and subjected to both shear and torsion. There are presently equations presented in codes such as ACI440 or b CEB-FIP for determining the shear resistance of such beams [11,12]. While research eorts still continue in this area, there are only a few codes which provide relations for calculating torsion resistance in strengthened beams. In doing so, these relations use a combination of concrete, stirrup, and FRP capaci- ties, similar to the case with shear resistance calcu- lations [12,13]. Recent investigations, however, have indicated the inadequacy of this method. Deifalla and Ghobarah, for instance, carried out a comprehensive comparison of calculation results obtained from lab- scale experiments and those obtained from the b code to show that the average capacity obtained by the b code only accounted for around 30% of the laboratory results . Moreover, no mention is made in recent
The focus of this paper is to better understand the influence of internal steel reinforcement and partial or full external FRP wrap/reinforcement on concrete con- finement. A series of finite element (FE) models are developed to analyze the effect of the aforementioned parameters on the confined concrete column. FE models have been successfully used to simulate the behavior of RC beams (Hawileh et al. 2012; Hawileh et al. 2013) and columns (Mirmiran et al. 2000) wrapped by FRP sheets. The influence of partial wrapping on the increase in strength and ductility is evaluated. The results from the FE parametric analyses were used to derive a new con- fined concrete compressive stress–strain model for con- centrically loaded RC circular columns that are partially and fully wrapped with FRP.
The evolution of bridge technology in United States begins with colonial carpenters and masons building mostly short-span bridges of timber or stone. During 18th century, long span wood truss bridges (trestle bridges) often covered with siding and a roof to protect the load-carrying trusses were built (Ritter, 1990). The beginning of Industrial revolution in 19 th century required the construction of transportation infrastructure and an increase in usage of timber as a primary construction material. Wood design methodologies, lamination, preservative treatments, etc. are some of the major technological advances related to timber usage in the 20th century (Ritter, 1990). This research work deals with the use of timber and fiber reinforced polymer (FRP) for design and construction of bridges including repair of bridge column and beam elements. Specifically, a pedestrian bridge has been designed to be built at Jackson Mill, West Virginia using timber, FRP, and steel materials.
There have been numerous investigations into blast loading of structures using open air charges and under water charges , several studies have investigated dynamic deformations due to explosive blast loading on reinforced concrete structures. Chaochen Zhai et al conduct both experimental and numerical investigation on RC beam subjected to blast loading  they concluded that, the peak and residual displacements during blast increased nearly linearly with the fire duration. A. Ghani Razaqpur et al  both experiment and numerically proved that the longitudinal reinforcement and and stand -off distance are the main criteria’s effect the failure. Aditya Kumar Singh et al  theoretically calculate the differnt thye of blast and their load .Wang et al  theoretically calculate the response of simply supported steel beam under blast at elevated temperature Hrvoje Draganić  conduct study on 4 story concrete frame and they derive method to calculate blast load on structures. Ngo et al  investigated the structural stability and integrity of the building by considering the effects of the failure of some perimeter columns, spandrel beams and floor slabs due to blast overpressure.Murtha and Crawford et al  suggested that the nominal static diagonal- strength of RC beams be increased by 50%. A three-step explicit numerical method based on the layered Timoshenko beam element approach was proposed by Fang et al. [8,9] to analyse the fire resistance of steel members after explosion. Menkes and Opat et al  have shown that a structural member governed by flexure under static loading may fail in shear under high intensity and short duration loads. This paper aims at investigating the reduction of structural failure by adopting facet structure used in sound proofing mechanism in blast loading by reducing the impact of pressure wave on RC beam. The numerical investigation is conducted using the software AUTODYN by adopting the weight of explosive as 7kg and stand-off distance as 1.5m. The redesign of beam is conducted based on indian standard ( IS 456 2000)
External FRP links were employed as shear reinforcement to facilitate the monitoring of deformations and to gain an additional insight into strain distribution along the link length using Digital Image Correlation. The FRP links were wrapped continuously around the beam, with an overlap in the top part of the beam perimeter eliminating the possibility of premature delamination. The external FRP links (Fig. 2b) were manufactured in the laboratory using continuous strips of glass and carbon fibre sheets impregnated with an epoxy resin. The two types of fibres were used to investigate the influence of link stiffness on the cracking and overall shear behaviour of the beams. GFRP links were used in specimens GB60, GB62 and GB64, while CFRP links were used in GB61, GB63 and GB65. The shear reinforcement was designed to provide the minimum shear reinforcement ratio of fv,min =0.35/f fv recommended in ACI 440.1R-15 (Table 3).
Control RC column have failed after reaching to their ultimate load carrying capacity with a blasting effect shown in fig 5(a).During the load application of all the FRP confined columns, typical sound was heard signifying the stretching of FRP sheets and crushing of epoxy resin. CB1 (column confined with 2 layers of BFRP sheets) and CB2 columns (column confined with 2 layers of BFRP sheets) were failed by the rupture of BFRP sheets at the top shown in fig 5 (b) and fig 5 (d). In case of column CC2 (column confined with 2 layers of CFRP sheets) the CFRP at the top and bottom of the column is found to be undamaged at the time of failure shown in fig 5 (g) . Among all FRP confined columns BFRP wrapped column failed suddenly by the rupture of BFRP sheets. In case of CC1B1 and CB1C1 hybrid wrapped columns failure is found to be bulging of column at the top without bursting the FRP sheets shown in fig 5 (e) and and fig 5 (f) respectively.
The FE models consisted of sixteen RC deep beams with openings of different shapes and sizes. The specimens were divided into four groups (A, B, C and D) according to the opening shape and size. Each group consisted of four RC deep beams with openings. One specimen in each group was used as a control unstrengthen specimen. The compressive strength of specimens in group A, B. C. and D were 25MPa. The model of deep beam used in this thesis paper is taken from the study done by Qudeer Hussain and Amorn Pimanmas (2015) on paper titled ”Shear Strengthening of RC Deep Beams with Openings using Sprayed Glass Fiber Reinforced Polymer Composite (SGFRP): Part 1. Experimental Study”. The cross section of all the deep beams were width = 100 mm and total depth = 500 mm. The total span length of the beam was 870 mm, and the shear span length was 435 mm. Two opening shapes (i.e., circular and square) were used with two different sizes for each shape. The size of the square opening was 120 × 120 mm and 180 × 180 mm, and the diameter of circular opening was 100 mm and 160 mm. In all specimens, one opening is provided at the centre of each shear span. Each beam contained two numbers 12mm diameter bars (yield strength of 415 MPa) at the bottom face, and top two number 6mm diameter bars (yield strength of 250 MPa) at the top face. The web reinforcements consisted of 6mm diameter bars provided at 110 mm spacing in both vertical and horizontal directions. Stirrups were used as the vertical web reinforcement, and straight bars were used as the horizontal web reinforcement. Closely spaced vertical stirrups were provided at both ends of the beams to avoid premature failure at these locations.
and service ducts openings are provided through the beams. Due to the presence of web opening in the rc beams resulted in many problems including reduction in beam stiffness, excessive cracking and deflection and reduction in beam capacity .In this project the behavior of R.C.C. beam with rectangular opening strengthened by CFRP, AFRP,GFRP,BFRP,BORON FRP are studied. This project presents the most effective and fastest method of strengthening beams with opening. In this analytical study total eight beams are model, one beam without opening (i.e. solid beam), and one beam with rectangular shear opening and last one with rectangular flexural opening. These three considered as a control beams for comparison. The remaining five beams will strengthened by CFRP, AFRP, GFRP, BFRP, BORON FRP. These beams will analyzed using ANSYS17. From the analytical study resuls it is concluded that the maximum load carrying capacity of the R.C.C. beam with flexure opening strengthened with GFRP, CFRP, AFRP, GFRP, BFRP, and BORON FRP increases from 38% to 62%.among these tested materials BORON FRP shows high increase in strength.
As to torsional members with open thin-walled sections, the warping effect is not negligible. According to Vlasov’s elastic theory of the open thin-walled member (Vlasov 1961), when the warping deformation of an open thin-walled member under torsion is restrained, a new internal force called warping moment corresponding to warping normal stress will appear. When it occurs, two kinds of internal torque appears simultaneously, which are circulatory torque (the same as that in the closed section case) and warping torque. In 1961, Vlasov (1961) developed the sectorial coordinate system and derived the theoretical formula to calculate warping torque and warping moment for open thin- walled members, which became the basis for analyzing open thin-walled members under torsion. Thereafter, some research outcomes on the elastic torsional response of the open thin-walled member, especially focusing on the shear deformation induced by the warping torque, have been reported (Pavazza 2005; Erkmen and Mohareb 2006; Murı´n and Kutisˇ 2008; Aminbaghai et al. 2016). When it comes to the post cracking torsional behavior of RCmembers with an open thin-walled section, the above mentioned softened truss model for circulatory torsion is not accurate anymore because of the considerable warping effect (Luccioni et al. 1991). In addition the Vlasov’s elastic theory should be revised due to the cracking of concrete. Zbirohowski-Koscia (1968) ﬁrst addressed issues related to the post-cracking behavior of open thin-walled RC beams under the warping moment. In 1981, Krpan and Collins tested the torsional response of a ﬁxed–ﬁxed U-shaped thin-walled RC beam (Krpan and Collins 1981a). The results conﬁrmed the dominate role that the warping moment played. In the analogy to bending, based on Vlasov’s theory, the method to simulate the post cracking torsional behavior of the U-shaped thin-walled RC beam was proposed (Krpan and Collins 1981b). Then Hwang and Hsu (1983) analyzed the entire torsional behavior of the RC channel beam with a method from the Fourier series approach. In the following two decades, few research outcomes on the torsional behavior of open thin-walled RCmembers under torsion were reported in literature. Due to the wide application of U-shaped thin-walled RC beams in the construction of rail viaducts in recent years, their torsional behavior has again drawn research’s attention. Theoretical and experimental studies on the torsional behavior of U-shaped thin-walled RC beams have been carried out by our research group (Chen et al. 2016a, b), and based on Vlasov’s torsional theory and the nonlinear constitutive relations of materials, a
For all FRP/TRM strengthened beams tested at high tempera- ture, five type K thermocouples were mounted to the concrete sur- face prior to the application of the strengthening materials in order to monitor the temperature at concrete – adhesive interface. As shown in Fig. 5d, the thermocouples were distributed along the critical strengthened flexural span to ensure that the targeted tem- perature (i.e. 150 ° C) is uniformly reached along that span. The test procedure at high temperature included the following steps: the heating system was placed underneath the specimen; the height of the legs was adjusted in order to achieve a distance of 100 mm (to allow for beam’s deflection) between the heaters and the beam’s soffit (Fig. 5c). The specimen was heated up to the pre- defined temperature (i.e. 150 ° C), and then loaded monotonically up to failure, while the temperature at the concrete - adhesive interface was approximately kept constant at 150 ° C. The data of the tests was recorded using a fully-computerized data acquisition system.
Sheikh et al. (2002) studied the damage sustained by foundation walls and large beams in a building simulated in full-size to near-full-scale model specimens in the laboratory. The damaged specimens were repaired with carbon and glass fiber-reinforced polymer (CFRP and GFRP) sheets and wraps, and tested to failure. Test results showed that fiber-reinforced polymers (FRP) were effective in strengthening for flexure as well as shear. Available analytical procedures and building code provisions were found to simulate the behaviour of specimens retrofitted with FRP reasonably well. The experimental program included testing of three wall-slab specimens and two beams. The wall-slab specimens were 250 mm thick, 1200 mm wide, and 1.2 m long, and the beams were 550 mm wide, 1000 mm deep, and 4.8 m long. Various analytical techniques were used to simulate experimental behaviour of the specimens. Both carbon and glass composites provided significant enhancement (more than 148%) in flexural strength to the extent that the failure of the wall-slab specimens shifted to shear mode which, in some cases, may not be acceptable. The wrapping of the beam of section size 550 x 1000 mm with one layer of CFRP resulted in changing the brittle mode of shear failure at 1700 kN to a very ductile flexure failure at 2528 kN. The deflection at failure increased from 14 mm in the control specimen, to 143 mm in the retrofitted specimen. The theoretical failure load for the retrofitted beam based on its shear capacity was approximately 5000 kN.
The FEM analysis of columns confined with ferrocement and FRP sheet is carried out using finite element software ANSYS Workbench 17.0. The maximum load observed for unconfined column is 800kN, hence a higher load 1000kN is selected for studying the deformation characteristics on the confinement of CFRP sheets and ferrocement. The deformations of all types of columns are recorded for a constant axial load 1000kN for different support conditions (bottom fixed top free, fixed hinged support and hinged hinged support). The characteristics of the deformation- L/D ratio curves for the unconfined, FRP confined and ferrocement confined columns are summarized in Tables 3.1 to 3.4.
Fiber-Reinforced Polymer (FRP) materials have being widely used in civil engineering applications for more than three decades. Well established analytical models are already available for FRP strengthened beams and columns under flexural and axial loadings. However, the behavior of such members under shear stress field is still under investigation due to the high level of complexity associated with the shear behavior (Zararis 2003). Most of the available analytical models for predicting the shear behavior of FRPRCmembers resulted in relatively large discrepancies when compared to experimental results (Belarbi et al. 2011). The most important reason for this is the lack of accurate stress strain relationships for FRPRC elements. In the previous developed models and design codes, the shear contributions of concrete, internal steel reinforcements and externally bonded FRP reinforcements were derived independently. However, the high level of interaction between these materials should be considered (Bousselham and Chaallal 2008; Chen et al. 2010). To accurately predict the behavior of FRPRC elements in shear, the stress - strain relationships of each component and the interactions among them have to be carefully investigated.
To this extend, the strategy adopted in this thesis (and outlined in figure 1.2) in order to address the identified research gaps consists of the following steps/studies: Firstly, in (§4. Influence of Bi-Directional Pounding on the inelastic Demand Distribution of Three Adjacent Multi-Storey RC Buildings) attention is focused on a real-life configuration of buildings (corner city block) as a case study that allows for the concurrent examination of different scenarios arising in real-life settings. These scenarios include a) pounding between building with significantly different design specifications b) pounding between buildings with unequal number of floors c) pounding between buildings that at least one of them exhibits torsional sensitive behaviour and d) bi-directional pounding of a corner building in an urban building block. The level of sophistication of the three-dimensional nonlinear FE model developed accounting for impact as well as hysteretic structural response renders this study novel in the literature. The seismic excitation is represented by a single pair of artificial accelerograms whose response spectrum matches closely the Eurocode 8 spectrum used in designing the buildings.
Metwally  evaluates the punching shear strength of RC flat slabs reinforced with different types of FRP. The experimental punching shear strengths were compared with the available theoretical predictions and a number of existing models and two approaches for predicting the punching strength of FRP-reinforced slabs are proposed. Koppitz et al.  performed an experimental study of full-scale reinforced concrete flat slabs crosswise strengthened with prestressed CFRP straps against punching shear. They found that, Strap activation and thus strap force increments were higher in cases with either lower prestressing or higher strap stiffness and the deformability of the steel frame allowed a balancing of the strap forces.