Shear Performance Of RC Beams Research Articles

Influence of deteriorated stirrups on the shear performance of RC beams incorporating fly ash and enhanced with carbon fiber-reinforced polymer strengthening

Influence of deteriorated stirrups on the shear performance of RC beams incorporating fly ash and enhanced with carbon fiber-reinforced polymer strengthening

A REVIEW OF HYBRIDISED USE OF FIBRES IN SHEAR BEHAVIOUR OF FIBRE-REINFORCED CONCRETE BEAMS

Shear failure of the concrete beam is always disastrous due to unnoticed occurrences and is avoided in construction. Introducing fibres into concrete elements has provided significant shear support to reinforced concrete beam structures through stress redistribution after initial cracking and bridging mechanisms. Given their advantages over single fibre strengthening in past years, using hybrid fibres in an optimal combination as strengthening in cementitious materials has drawn much interest. However, research on this area remains inexhaustible based on the emerging various fibre combinations and the challenge of unnoticed concrete shear failure. Therefore, reviewed research articles on shear performances of Fibre Reinforced Concrete (FRC) beams considering the effect of fibre volume, lengths and orientation on the synergy. The findings reveal the possibility of synergising fibre to enhance reinforced concrete beam(RCB) shear performance for metallic-metallic, metallic-synthetic, synthetic-synthetic, and metallic-biofibre combinations, with varying performance. Using low-strength/modulus fibre with high strength has been effective for shear resistance. Also, beam type (deep/shallow), fibre type and volume fractions, length, aspect ratio, orientation and distribution remarkably affect the shear performance of RC beams.

Shear performance and size effect of CFRP strengthened RC beams

In this study, a 3D meso-scale numerical simulation method is established for analyzing the shear failure of carbon fiber reinforced polymer (CFRP) strengthened RC beams without stirrups. The inhomogeneity of concrete, the bond-slip relationship between steel bars and concrete, and the interaction between CFRP and concrete are considered. Based on this method, effects of shear-span ratio and CFRP fiber ratio on the shear performance and nominal shear strength size effect of CFRP strengthened RC beams are investigated. Results indicate that the size effect of CFRP strengthened RC beams is obvious, however, the shear-span ratio has little impact on the size effect of nominal shear strength of RC beams. The CFRP fiber ratio enhances the shear strength of RC beams on the one hand, while weakens the shear size effect of RC beams on the other hand. However, its influence on the shear performance of RC beams remains basically unchanged with varying shear-span ratios, indicating that there is no coupling effect between the shear-span ratio and CFRP fiber ratio. The shear-span ratio significantly influences both the shear bearing capacity of RC beams and the shear contribution of CFRP sheets, with the increase in the shear-span ratio, the shear bearing capacity of RC beams decreases to varying degrees, and the shear contribution of CFRP sheets increases initially and then decreases. Finally, the shear strength size effect law (SEL) of CFRP strengthened RC beams is proposed, which can quantitatively describe the effects of the shear-span ratio and the CFRP fiber ratio.

Mechanism of improvement in the shear performance of RC beams due to multiple small transverse openings

This paper evaluated the improvement effect of multiple small circular transverse openings (diameter is 1/10 of member height) on the shear performance of RC beams without shear reinforcement and explained the shear resistance mechanism, using three dimensional Rigid-Body-Spring-Method (3D RBSM). First, 3D RBSM was employed to reproduce the shear loading test on the RC beams with multiple small circular transverse openings, and the contributions of beam and arch actions to the shear resistance at each loading stage was evaluated. The analytical load-deflection relationship and cracking behavior were in good consistent with the experiment, and it was noted that the connecting line of the opening centers (line of openings) could control the path of critical diagonal crack, and transfer the failure mode of one of the beams from the diagonal tension pattern to the shear compression pattern. Moreover, the shear strength and ultimate deflection of this beam with openings were significantly improved due to the increase in the shear resistance contribution of arch action. Furthermore, the analysis of additional cases with three transverse openings at each shear span were conducted aiming to explore the possibility that a proper setting of openings can reliably improve the shear performance of RC beams. The line of openings was on a straight line and passed through the loading point at the same side, and the main parameter was set as the angle of the line of openings to beam axis (25°-50°). As a result, the role of the transverse openings in improving the shear performance was confirmed and the corresponding mechanism was explained based on the investigation on the beam and arch actions and crack behaviors.

Experimental study on shear performance of RC beams strengthened with NSM CFRP prestressed concrete prisms

This paper presents an experimental investigation of the shear performance of RC beams strengthened with near surface mounted (NSM) carbon fibre reinforced polymer (CFRP) prestressed concrete prisms (PCPs). The shear behaviour of strengthened beams can be affected by several design variables. In this research, the effect of the following parameters were considered: the prestress level, inclination and spacing of the CFRP-PCPs, and material type of the prism. The control beam had conventional shear steel reinforcement only while the other seven beams were shear strengthened with CFRP-PCPs by varying design parameters mentioned above. All the beams were tested under monotonic loading until they reached the failure load. The experimental results showed that the NSM CFRP-PCPs strengthening technique improves the shear performance of the beams effectively. The strengthened beams that applied the CFRP-PCPs at an inclination of 45° were more efficient in improving the shear capacity compared to vertical CFRP-PCPs. The shear capacity and deformation were enhanced with the increase of prestressing levels of CFRP rods and the decrease of CFRP-PCPs spacing. The failure modes of the strengthened beams were influenced mainly by the spacing and the inclination of the CFRP-PCPs. Moreover, the material type of the prism had little influence on the effectiveness of shear strengthening. The analytical model presented was developed to estimate the shear contribution of NSM CFRP-PCPs and the model was found to predict the shear capacity of the tested beams well.

개구부를 사각 및 팔각형의 철근으로 보강한 철근콘크리트 보의 전단성능에 관한 연구

개구부를 사각 및 팔각형의 철근으로 보강한 철근콘크리트 보의 전단성능에 관한 연구

Shear Performance of RC Beams with Externally Bonded FRP Wraps

This examination demonstrates the shear execution of invigorated bond (RC) shafts fortified with remotely braced carbon fiber reinforced polymer (CFRP) wraps and Glass fiber sustained polymer (GFRP). The test program involved testing six, full-scale, RC columns. The components investigated in this investigation concentrate included steel stirrups. As a segment of the examination program, the test concentrate investigated the reasonability of CFRP and GFRP fortress in improving the shear furthest reaches of RC bars, and for bars with rectangular fragment. The test outcomes demonstrated that the responsibility of remotely braced CFRP and GFRP to as far as possible is basic and subordinate upon the variable inspected. Where they are finally taken a gander at and investigated that the going with which is more astute to be used in the field of advancement. Keywords: CFRP, GFRP

Experimental study on the shear performance of RC beams reinforced with welded reinforcement grids

The performance of welded reinforcement grids (WRGs) made of smooth rebar, as shear reinforcement for RC beams, was investigated through monotonic and cyclic loading tests, in comparison to conventional bent smooth and deformed stirrups. The influence of the two main differences of the WRG to the conventional bent stirrups, i.e. the low bond stress and the limited strength of weld, on the performance of specimens was analyzed, based on the test observations, load-displacement curves and strain in the shear reinforcement. Test results showed that the WRG-reinforced beams had similar behavior and failure modes to the specimens reinforced with bent smooth stirrups, in both monotonic and cyclic loading tests. However, under cyclic loads, the shear capacity of beams was negatively influenced by the insufficient bond stress between smooth rebar and concrete. To overcome this deficiency, a new type of WRG, with an additional horizontal rebar branch to provide mechanical anchorage, was proposed and its effectiveness was experimentally examined. Finally, modifications were made to an existing formula to predict the contribution of the WRG to the shear capacity, based on the actual strength of weld covered by the concrete, obtained using the an experimental method proposed in this study.

Improving the shear performance of reinforced concrete beams made of recycled coarse aggregate

This paper investigates experimentally and analytically the shear performance of RC beams made of recycled coarse aggregate (RCA). Previous studies showed that the partial replacement of the virgin coarse aggregate by recycled one results in decrease the shear strength of RC beams. Consequently, the main target of the this research was to compensate such decrease in the shear strength by providing internal short fibers and using cured recycled coarse aggregate instead of crude recycled coarse aggregate. A total of eleven simply supported RC beams made of recycled coarse aggregate along with one conventional concrete beam were tested under incremental four-point loading scheme. The considered parameters were the recycled coarse aggregate replacement ratio (15, 30 and 45%), the shear span-to-depth ratio (1, 2 and 3) and the fiber volumetric ratio (1, 1.5 and 2%). In addition, to improve the physical and mechanical properties of the recycled coarse aggregate (RCA), two curing methods for the RCA were implemented using cement slurry and Styrene Butadiene Rubber (SBR) compound. The experimental results showed that increasing the replacement ratio of the RCA resulted in decrease the shear capacity proportionally. The percentages of decreases in the shear capacities were about 8%, 14% and 19%, respectively, for RC beams provided by RCA replaced by 15%, 30% and 45%. In addition, it was shown that providing internal short fibers by volumetric ratios of 1%, 1.5% and 2% enabled the RC beams made of 30% partial replacement of the recycled coarse aggregate to compensate the decreases in the shear capacities (14%) and to increase their shear capacities by about 13%, 15% and 22% compared to those of the control beam, respectively. Furthermore, for RC beams made of 30% partial replacement of the RCA, the shear capacities decreased by about 2%, 14% and 37%, respectively, for beams having shear span-to-depth ratio of 1, 2 and 3. Besides, it was shown that, the cured recycled coarse aggregate enabled the RC beams made of 30% partial replacement to exhibit improved shear performance. However, the curing method based on cement slurry showed higher improvement since the restored shear capacities were about 15% and 3% for beams provided by cured coarse aggregate based on cement slurry and compound SBR, respectively compared to that of the beam made of crude RCA. Finally, an equation for estimating the shear capacity of RC beams made of recycled coarse aggregate was proposed and it showed satisfactory results when verified against the experimental findings of the current research as well as of other researches where the maximum variations were about 8.5% and 22%, respectively.

Shear Resistance of RC Beams Strengthened with Combined CFRP and Steel Plate

The purpose of this study is to investigate shear performance of RC beams strengthened with combined CFRP and steel plates. Fourteen beams were tested to shear failure under simply supported four-point loading conditions. The variables of this investigation included strengthening technique, shear span to depth ratio, percentage of CFRP, percentage of steel plate, CFRP and steel plate orientation, CFRP and steel plate wrapping type. The results show that the simultaneous application of CFRP sheets and steel plate greatly increases the shear resistance of RC beams. The steel plates improve the bond behavior of CFRP sheets. A design formula is proposed to calculate the shear resistance of the beams strengthened with combined CFRP sheets and steel plates. The predictions agree well with the test results.

Shear performance of reinforced concrete beams with corroded stirrups in chloride environment

Experiments were conducted for the investigation of the influence of reinforcing steel corrosion on the shear capacity of reinforced concrete beams. The shear performance of RC beams with different corrosion levels in both longitudinal reinforcing steel bars and stirrups was examined. Relationships of corrosion-induced crack widths in concrete cover with the corrosion level of the reinforcing steel bars were obtained. Engineering approaches were developed to predict the residual shear strength of the corroded beams.