Influence of the supplementary reinforcement on the shear strength of beams with prefabricated truss stirrups

abstract: This paper presents the results of seven experimental tests in reinforced concrete wide beams, aiming to investigate their performance when subjected to shear, using prefabricated truss stirrups as shear reinforcement, as well as a supplementary reinforcement to control cracks by delamination. The main analysed variables were: position of the supplementary reinforcement, inclination of the shear reinforcement, and spacing between stirrups. Results showed that strength increments of up to 142% were obtained using the prefabricated truss stirrups. Furthermore, the experimental results were compared with the theoretical shear strength estimates of the tested beams, following the recommendations of NBR 6118 (2014), Eurocode 2 (2004), and ACI 318 (2014), in order to evaluate the safety level of these codes when designing concrete elements subjected to shear with the reinforcement used in this paper.

Effect of short glass fiber on shear capacity for shallow wide reinforced concrete beams

Shallow wide reinforced concrete beams are used in modern buildings especially in residential building structures. According to current Egyptian Code Practice 203-2018; the characteristic of a shallow wide concrete beam is that the cross-section width (b) over the effective depth (d) ratio is greater than two and the beam depth is less than 250 mm. Without any shear reinforcing contribution, the applied shear stresses in shallow wide beams must be less than the concrete shear strength. And only concrete provides shear strength. An experimental program was conducted to investigate the contribution of short glass fiber polymer reinforcement to shear strength in shallow wide beams under shear stress. The short glass fiber polymer reinforcement ratio was the main parameter in this study. And also, the contribution of web shear stirrups reinforces against shear stresses. The experimental program consisted of five simply supported reinforced shallow wide concrete beams. Test results show that the use of short glass fiber reinforced polymer has a great effect on shear strength capacity, mode of failure, and ductility of shallow wide concrete beams.

Behavior of RC Wide Beams under Eccentric Loading

Wide beams are one of the widely used structural elements in RC buildings due to the many special features that characterize them. The main objective of this research is to investigate the behavior of wide shallow beams under the effect of eccentric loading acting along their cross sections. To achieve that, an experimental program that consisted of seven wide beams was conducted. All beams were loaded using two concentrated loads at their middle third where the main parameters considered were: the magnitude of the load eccentricity, the longitudinal spacing between shear reinforcement, and the arrangement of the longitudinal reinforcement. Following that, a finite element analysis was performed where the analytical model used was first verified using the data from the experimental program. The results from both the experimental and analytical programs were in good agreement. Then, the finite element analysis was extended through a parametric study where other variables were studies such as the compressive strength of concrete, the transverse spacing between stirrups and the longitudinal reinforcement ratio. The results showed that the value of the load eccentricity, spacing between shear reinforcement, the arrangement of the main reinforcement along the beam cross section, and the compressive strength of concrete significantly affected the torsional resistance of shallow wide beams. Conclusions and recommendations are presented which can be useful for future researchers. Doi: 10.28991/cej-2021-03091766 Full Text: PDF

Sectional Ductility of Wide Beams

Wide beam structures are categorized as Limited Ductility Class in Turkey and elsewhere and considered not fit for construction in areas of high seismicity. One of the main reasons that wide beam structures are considered to possess limited ductility is the perceived low local ductility of the wide beams, due to the high reinforcement ratios. Wide beams have small depths, which indeed require higher reinforcement ratios to produce the necessary moment capacities, as compared to normal beams. However, the low local ductility of the wide beams can be contested. This paper presents a database of more than 150 beam sections, some of which are normal and some of which are wide beams. The moment-rotation relationships were computed for all the sections, and the sectional ductility was calculated from the yield and ultimate rotations. The relations between sectional ductility and other parameters such as section aspect ratio, longitudinal reinforcement ratio and transverse reinforcement ratio were investigated. An example of the relation between ductility and section properties, in this case section aspect ratio is shown. Both positive and negative ductility were calculated and plotted. It should be noted that beams with section ratio of 0.5 are conventional beams, while the rest are wide beams. The values of ductility vary for all beams, and conventional beams have a slightly wider spread. While these parameters vary within the section database, the sectional ductility oscillates around 30, and no clear correlations could be established for any of the above-mentioned parameters. There were no significant differences between the average sectional ductility of conventional and wide beams. For this dataset, the mean positive ductility was 29.66 and 29.33 for conventional and wide beams respectively, and the mean negative ductility was 28.96 and 31.50 for conventional and wide beams, respectively.

Study Effect the Shear Spacing and Width of Beam on Behavour of Reinforced Concrete Wide Beams

This paper presented an experimental study of the behaviour of wide reinforced concrete beams with different shear spacing and beam width. Eight specimens in two groups, the group one contains four specimens with the dimensions of (200x500x1600mm) and shear reinforcement spacing (d/2, 0.65d, 3/4d and 1.0d), the group two contains four specimens with the dimensions of (200x600x1600mm) and shear reinforcement spacing (d/2, 0.55d, 3/4d and 1.0d), Variables studied in this study shear reinforcement spacing and width of wide beam, the increasing of shear reinforcement spacing gives close results in RC wide beam, increased shear reinforcement spacing decreased the ultimate loud by 6.6% and when increasing width of beam the ultimate loud decreased by 9.5%, The ultimate deflection decreased by 16.5% and when increasing width of beam decreased by 7.2 %,The number of flexural cracks was equal in all beams, when increasing width of beam the number of flexural crack increased by 2 cracks, The average spacing between shear cracks decreased by 7%, when increasing width of beam average spacing between shear cracks decreased by 19%.

Study of Change in Width to Depth Ratio of RCC Beam in Shear for M-25 Grade of Concrete

In this study focused member with typically b/d ratio of members once a parameter of depth constant and another parameter is width constant. Additional consideration should be given to member having b/d ratio of about its analyzing and designing resistivity, which are also representative of wide beams used in industry. Each of these geometric relationships should be considered in the context of member with web reinforcement.