yes / The main purpose of this paper is to assess moment redistribution in continuous concrete beams reinforced with fibre reinforced polymer (FRP) bars. A numerical technique based on equilibrium of forces and full compatibility of strains has been developed to evaluate the moment–curvature relationships and moment capacities of FRP and steel reinforced concrete sections. Moment redistribution has then been assessed by comparing elastic and experimental moments at failure, and moment capacity at critical sections of continuous FRP reinforced concrete beams reported on the literature. The curvature of under reinforced FRP sections was large at FRP rupture but failure was sudden, that would not allow any moment redistribution. On the other hand, FRP over reinforced sections experienced higher curvature at failure than steel over reinforced sections owing to the lower FRP modulus of elasticity. Although the experimental and elastic bending moment distributions at failure are significantly different for many beams tested elsewhere, in particular CFRP reinforced concrete beams, the experimental bending moment over the middle support at failure was far lower than the corresponding moment capacity owing to the de-bonding of FRP bars from concrete in the middle support region. Furthermore, the hogging moment redistribution over the middle support is always larger than that at mid-span by around 66%. It was also shown that the load capacity prediction of continuous FRP reinforced concrete beams using the de-bonding moment at the middle support section was the closest to the experimental failure load.

yes / Twenty two reinforced concrete continuous deep beams with openings and two companion solid deep beams were tested to failure. The main variables investigated were the configuration of web reinforcement around openings, location of openings, and shear span-to-overall depth ratio. The influence of web reinforcement on controlling diagonal crack width and load capacity of continuous deep beams with openings was significantly dependent on the location of openings. The development of diagonal crack width and load capacity of beams having openings within exterior shear spans were insensitive to the configuration of web reinforcement. However, for beams having openings within interior shear spans, inclined web reinforcement was the most effective type for controlling diagonal crack width and increasing load capacity. It has also observed that higher load and shear capacities were exhibited by beams with web reinforcement above and below openings than those with web reinforcement only above openings. The shear capacity at failed shear span of continuous beams tested is overestimated using Kong et al’s formula developed for simple deep beams with openings.

Yes / The current design codes, such as ACI 318-14, EC2 and CSA23.3-04, in addition to previous research investigations suggested different expressions for concrete effectiveness factor for use in limit state design of concrete structures. All these equations are based on different design parameters and proposed for normal concrete deep beams. This research evaluates the use of different effectiveness factor equations in the upper and lower bond analyses of continuously-supported self-compacting concrete (SCC) deep beams. Moreover, a new effectiveness factor expression is suggested to be used for upper and lower bound solutions with the aim of improving predictions of the load capacity of continuously-supported SCC deep beams. For the range of deep beams considered, the strut-and-tie method with the proposed effectiveness factor formula achieved accurate predictions, with a mean of 1.01, a standard deviation of 6.7% and a coefficient of variation of 6.8%. For the upper-bound analysis, the predictions of the proposed effectiveness factor equation were more accurate than those of the formulas suggested by previous investigations. Overall, although the proposed effectiveness factor achieved very accurate predictions, further validation for the proposed formula is needed since the only data available on continuous SCC deep beams are those collected form the current study.

Yes / The results of testing two simply and three continuously supported concrete beams reinforced with glass fiber-reinforced polymer (GFRP) bars are presented. The amount of GFRP reinforcement was the main parameter investigated. Over and under GFRP reinforcements were applied for the simply supported concrete beams. Three different GFRP reinforcement combinations of over and under reinforcement ratios were used for the top and bottom layers of the continuous concrete beams tested. A concrete continuous beam reinforced with steel bars was also tested for comparison purposes. The experimental results revealed that over-reinforcing the bottom layer of either the simply or continuously supported GFRP beams is a key factor in controlling the width and propagation of cracks, enhancing the load capacity, and reducing the deflection of such beams. Comparisons between experimental results and those obtained from simplified methods proposed by the ACI 440 Committee show that ACI 440.1R-06 equations can reasonably predict the load capacity and deflection of the simply and continuously supported GFRP reinforced concrete beams tested.

Yes / Ten reinforced-concrete continuous deep beams with openings were tested to failure. The main variables investigated were the shear span-to-overall depth ratio, and the size and location of openings. Two failure modes influenced by the size and location of web openings regardless of the shear span-to-overall depth ratio were observed. The normalised load capacity of beams having a web opening area ratio of 0·025 within exterior shear spans was approximately similar to that of their companion solid beams. Continuous deep beams having web openings within interior shear spans exhibited a higher load capacity reduction with the increase of the opening size, similar to simply supported deep beams with web openings. Formulae based on the upper bound analysis of the plasticity theory were proposed to predict the load capacity of continuous deep beams with web openings. Comparisons between the measured and predicted load capacities showed a good agreement.

Yes / This paper describes a sequence of experiments on a long-span asymmetric composite cellular beam. This type of beam has become very popular, combining the composite action between the steel and concrete with the increased section depth, compared with more commonly used solid-web I sections. Openings in the steel web also reduce the self-weight and can accommodate the passage of service ducts. Eurocode 4 recommends a high degree of shear connection for asymmetric composite beams despite the practical difficulties in achieving this. Recent research suggests that the required degree of shear connection could be reduced, particularly for beams that are unpropped during construction. However, little test data exists to verify the behaviour of unpropped composite cellular beams. Therefore two series of tests were conducted on a 15.26 m long asymmetric composite cellular beam with regular circular openings and an elongated opening at the mid-span. The degree of shear connection was 36%, less than half of that recommended in Eurocode 4, and the beam was unpropped during construction. The beam was subjected to uniformly distributed loading and shear load during the tests. The end-slip, mid-span vertical deflection, shear connector capacity and strain distribution were examined. The beam failed at an applied uniform load of 17.2 kN/m2 (3.4 × design working load 5.0 kN/m2). The member withstood an applied shear load that was 45% higher than predicted, and exhibited a Vierendeel mechanism at the elongated opening. Overall, these tests demonstrated the potential of unpropped composite cellular beams with low degrees of shear connection. / RFCS

Yes / A full-scale composite floor plate was tested to investigate the flexural behavior and in-plane effects of the floor slab in a grillage of composite beams that reduces the tendency for longitudinal splitting of the concrete slab along the line of the primary beams. This is important in cases where the steel decking is discontinuous when it is orientated parallel to the beams. In this case, it is important to demonstrate that the amount of transverse reinforcement required to transfer local forces from the shear connectors can be reduced relative to the requirements of Eurocode 4. The mechanism under study involved in-plane compression forces being developed in the slab due to the restraining action of the floor plate, which was held in position by the peripheral composite beams; while the secondary beams acted as transverse ties to resist the forces in the floor plate that would otherwise lead to splitting of the slab along the line of the primary beams. The tendency for cracking along the center line of the primary beam and at the peripheral beams was closely monitored. This is the first large floor plate test that has been carried out under laboratory conditions since the Cardington tests in the early 1990s, although those tests were not carried out to failure. This floor plate test was designed so that the longitudinal force transferred by the primary beams was relatively high (i.e., it was designed for full shear connection), but the transverse reinforcement was taken as the minimum of 0.2% of the concrete area. The test confirmed that the primary beams reached their plastic bending resistance despite the discontinuous decking and transverse reinforcement at the minimum percentage given in Eurocode 4. Based on this test, a reduction factor due to shear connectors at edge beams without U-bars is proposed.

Yes / For composite beams with low degrees of shear connection, additional deflections occur due to slip in the shear connectors, which can be significant for beams with low degrees of shear connection. A design formula is presented for the effective stiffness of composite beams taking account of the stiffness of the shear connectors, which is compared to measured deflections of 6 symmetric beams and an 11m span composite beam of asymmetric profile. It is shown that the comparison is good when using a shear connector stiffness of 70 kN/mm for single shear connectors and 100 kN/mm for pairs of shear connectors per deck rib. Results of push tests on a range of deck profiles confirm these initial elastic stiffnesses. To ensure that the slip at the serviceability limit state does not lead to permanent deformations of the beam, it is proposed that the minimum degree of shear connection should not fall below 30% for un-propped beams and 40% for propped beams of symmetric cross-section. / European Commission

When subjected to a combination of moment and shear force, a reinforced concrete (RC) beam with either little or no transverse reinforcement can fail in shear before reaching its full flexural strength. This type of failure is sudden in nature and usually disastrous because it does not give sufficient warning prior to collapse. To prevent this type of shear failure, reinforced concrete beams are traditionally reinforced with stirrups. However, the use of stirrups is not always cost effective since it increases labor costs, and can make casting concrete difficult in situations where closely-spaced stirrups are required. The use of steel fiber reinforced concrete (SFRC) could be considered as a potential alternative to the use of traditional shear reinforcement. Concrete is very weak and brittle in tension, SFRC transforms this behaviour and improves the diagonal tension capacity of concrete and thus can result in significant enhancements in shear capacity. However, one of the drawbacks associated with SFRC is that the addition of fibers to a regular concrete mix can cause problems in workability. The use of self-consolidating concrete (SCC) is an innovative solution to this problem and can result in improved workability when fibers are added to the mix. The thesis presents the experimental results from tests on twelve slender self-consolidating fiber reinforced concrete (SCFRC) beams tested under four-point loading. The results demonstrate the combined use of SCC and steel fibers can improve the shear resistance of reinforced concrete beams, enhance crack control and can promote flexural ductility. Despite extensive research, there is a lack of accurate and reliable design guidelines for the use of SFRC in beams. This study presents a rational model which can accurately predict the shear resistance of steel fiber reinforced concrete beams. The thesis also proposes a safe and reliable equation which can be used for the shear design of SFRC beams.

When subjected to a combination of moment and shear force, a reinforced concrete (RC) beam with either little or no transverse reinforcement can fail in shear before reaching its full flexural strength. This type of failure is sudden in nature and usually disastrous because it does not give sufficient warning prior to collapse. To prevent this type of shear failure, reinforced concrete beams are traditionally reinforced with stirrups. However, the use of stirrups is not always cost effective since it increases labor costs, and can make casting concrete difficult in situations where closely-spaced stirrups are required. The use of steel fiber reinforced concrete (SFRC) could be considered as a potential alternative to the use of traditional shear reinforcement. Concrete is very weak and brittle in tension, SFRC transforms this behaviour and improves the diagonal tension capacity of concrete and thus can result in significant enhancements in shear capacity. However, one of the drawbacks associated with SFRC is that the addition of fibers to a regular concrete mix can cause problems in workability. The use of self-consolidating concrete (SCC) is an innovative solution to this problem and can result in improved workability when fibers are added to the mix. The thesis presents the experimental results from tests on twelve slender self-consolidating fiber reinforced concrete (SCFRC) beams tested under four-point loading. The results demonstrate the combined use of SCC and steel fibers can improve the shear resistance of reinforced concrete beams, enhance crack control and can promote flexural ductility. Despite extensive research, there is a lack of accurate and reliable design guidelines for the use of SFRC in beams. This study presents a rational model which can accurately predict the shear resistance of steel fiber reinforced concrete beams. The thesis also proposes a safe and reliable equation which can be used for the shear design of SFRC beams.