Type Of Shear Reinforcement Research Articles

Shear Behavior of Hollow Ferrocement Beam Reinforced by Steel and Fiberglass Meshes

The purpose of this study is to investigate the shear behavior of hollow ferrocement beams of self-compacting mortar reinforced with various types of metallic (steel wire mesh) and non-metallic (fiber glass mesh) reinforcement. The experimental program consists of casting eight ferrocement beams with dimensions of 150×225×2000 mm, with 50 mm of ferrocement thickness and a polystyrene cork core of 50×125 mm. The study parameters were the type of shear reinforcement and the number of layers of wire mesh. The results showed that the ultimate load of the beams reinforced with several layers of the fiber glass mesh (1, 2, and 3) was decreased by (3.27%, 16.52%, and 9.38%) respectively, compared to the beams reinforced with layers of steel wire mesh (1, 2 and 3). The ultimate load of these beams increased by (33.71%, 73.28%, and 122.11%) respectively, compared to the beams without shear reinforcement. Also, the ultimate load of the beams reinforced with layers of welded wire mesh was increased by (38.23%, 107.56%, and 145.09%) respectively, compared to the beams without shear reinforcement. The ductility and toughness of the beams reinforced with several layers of the fiber glass mesh (1, 2, and three) were decreased by (1.68%, 2.11%, 2.68%) and (29.39%, 25.91%, 16.06%) respectively, compared to beams reinforced with several layers of steel wire mesh (1, 2 and 3). The crack propagation was reduced and its number and crack width decreased by using steel wire mesh and fiber glass wire mesh instead of stirrups, especially in beams with two and three layers of wire mesh. The results also showed that the use of glass fiber or welded wire mesh in the reinforcement of hollow beams instead of steel stirrups has a significant effect on the failure load, deflections, crack patterns, and shear stresses, despite the clear preference for beams reinforced with steel wire mesh.

Experimental Evaluation of the Punching Shear Strength of Interior Slab-column Connections with Different Shear Reinforcement Details

This research aims to evaluate the effect of using different shear reinforcement details on the punching shear behavior of interior slab column connections. A comprehensive experimental program is conducted on sixteen specimens having the same concrete dimensions of 1100×1100×160 mm where the slab depth is chosen to be less than that stipulated by different design codes. The parameters under examination were the type of shear reinforcement arranged in a cross shape perpendicular to the column edges (single leg, multi-leg, and closed stirrups), the spacing between stirrups (25 and 50 mm), and the extended length covered by the stirrups (300 and 425 mm). Experimental results showed that slabs reinforced with multi-leg or closed stirrups, even for slabs with a thickness of 160 mm, had an increase in the shear capacity by up to 40% depending on the stirrup amount. A noticeable enhancement in ductility was also observed. Slabs reinforced with vertical single-leg stirrups did not exhibit any improvements. A finite element analysis was conducted to further assess the punching shear behavior of the tested specimens. A comparison between the test results and values obtained using design codes such as ACI 318-19 and ECP 203-2018 showed that the two design codes give a rather underestimated prediction of the punching shear capacity. Doi: 10.28991/CEJ-2022-08-09-015 Full Text: PDF

Shear strength of reinforced concrete beams with T-headed bars for safety-related nuclear structures

Excessive amounts of longitudinal and transverse reinforcement are required in concrete structures for safety-related nuclear structures to satisfy design and safety regulations. Closely spaced conventional single-leg stirrups are required for seismic detailing. These requirements lead to rebar congestion, difficulties in installation, and delay in the construction period. To solve these problems, it was proposed to use T-headed bars to replace the single-leg stirrups in this paper. A total of 12 tests were conducted to evaluate the effectiveness of using T-headed bars as shear reinforcement. The test parameters included height of beam, type of shear reinforcement (T-headed bars or stirrups), and shear span-to-depth ratio. It was shown from the test results that specimens with T-headed bars developed higher shear strength compared with specimens with conventional single-leg stirrups, while the behavior of these two types of specimens was similar. Design codes from six countries were then evaluated. It was concluded that these codes could provide conservative estimates of the shear strength for specimens with T-headed bars.

Improvement of punching shear strength of reinforced lightweight concrete flat slab using different strengthening techniques

This paper investigates the strengthening techniques of lightweight concrete (LWC) flat slabs vulnerable to punching shear failure. Thirteen reinforced LWC flat slab specimens were experimentally tested. The main investigated parameters were the type of shear reinforcement (steel bars, high strength bolts, or glass fiber reinforced polymers (GFRP) rods), spacing, shear reinforcement configuration around the column and the fixation method of shear reinforcement. The test results showed that using radial shear reinforcement with spacing of (d/2) resulted in the most efficient strengthening technique. The punching shear capacities were improved by 77%, 61% and 54% by using steel bars, glass fiber rods and high strength bolts, respectively, compared to the reference specimen. Moreover, using high strength steel bolts fixed to the slabs with steel plates showed the highest ductility compared with the other strengthening techniques Also, the failure mode converted from being brittle shear failure to flexural-shear mode. Non-linear finite element analysis (NLFEA) was carried out for the numerical verification. The analysis adequately reflected the trend of experimental results. Finally, the experimental test results were evaluated with code equations. The evaluation showed that the ACI 318 code underestimated the punching shear capacity of the tested specimens. On the other hand, Euro Code showed good prediction of the punching shear strength of the tested slabs.

English

This study is based upon the experimental investigation of shear reinforcement used in the reinforced concrete beams by using swimmer bars. In practice, vertical stirrup system is used in order to enhance the shear carrying capacity of beams. However in this research, a new type of shear reinforcement known as swimmer bars (inclined at an angle of 45°) are used in beams. Swimmer bars have more shear carrying capacity than vertical stirrups and can be placed with larger spacing. The effectiveness in terms of cost and shear carrying capacity is studied by casting beams in laboratory. The beam consisting of swimmer bars showed much more stiffness than beam with vertical bars. Also the ultimate load carrying capacity of swimmer bars is more than the vertical stirrups. Less number of cracks is formed in beams having swimmer bars. Keyword: Concrete, Shear, Swimmer bars, Stiffness

Shear Behavior of Concrete Beams Reinforced With A New Type of Glass Fiber Reinforced Polymer Reinforcement: Experimental Study.

The article presents experimental tests of a new type of composite bar that has been used as shear reinforcement for concrete beams. In the case of shearing concrete beams reinforced with steel stirrups, according to the theory of plasticity, the plastic deformation of stirrups and stress redistribution in stirrups cut by a diagonal crack are permitted. Tensile composite reinforcement is characterized by linear-elastic behavior throughout the entire strength range. The most popular type of shear reinforcement is closed frame stirrups, and this type of Fiber Reinforced Polymer (FRP) shear reinforcement was the subject of research by other authors. In the case of FRP stirrups, rupture occurs rapidly without the shear reinforcement being able to redistribute stress. An attempt was made to introduce a quasi-plastic character into the mechanisms transferring shear by appropriately shaping the shear reinforcement. Experimental material tests covered the determination of the strength and deformability of straight Glass Fiber Reinforced Polymer (GFRP) bars and GFRP headed bars. Experimental studies of shear reinforced beams with GFRP stirrups and GFRP headed bars were carried out. This allowed a direct comparison of the shear behavior of beams reinforced with standard GFRP stirrups and a new type of shear reinforcement: GFRP headed bars. Experimental studies demonstrated that GFRP headed bars could be used as shear reinforcement in concrete beams. Unlike GFRP stirrups, these bars allow stress redistribution in bars cut by a diagonal crack.

Behaviour of Reinforced Concrete Beams with Wire Mesh As Shear Reinforcement

This paper presents a study of shear behaviour of reinforced concrete beams. The major parameters used were type of shear reinforcement, namely stirrups alone, wire mesh alone and combination of both wire mesh and stirrups as shear reinforcement. The replacement of wire mesh was done on the basis of weight with stirrups. The experimental program includes four beams. All the beams were tested using two point loading system. It is evident from the result that the use of wire mesh enhanced improved shear performance and bearing capacity in the examined beams. Beams with wire mesh as shear reinforcement and combination of both wire mesh and stirrups exhibited some amount of increase in shear capacity with respect to the beams with stirrups alone as shear reinforcement. Furthermore beams with wire mesh and combination of wire mesh and stirrups as reinforcement exhibited less number of crack patterns compared beams with stirrups.

Study of Embedded Collar Head as Shear Reinforcement of High Strength Concrete of Flat Plate With Opening

This study displays an experimental investigation on one form of embedded shearhead called( collar head reinforcement) as shear reinforcement and it displays also theefficient uses of different forms of reinforced concrete . Also it displays the efficient of existence of opening on punching shear strength of reinforced concrete flat plate. In the present research, ten specimens are tested with dimensions (1000x1000x75 mm) which are divided into two groups; the first group is a normal strength concrete with a compressive strength 30MPa; the second group is high strength concrete with a compressive strength 60MPa. Each group consists of five specimens, the first specimen is reference specimen R , and second specimen with opening adjacent to the column but without collar head No 1, and third specimen] with presence of openings adjacent to the column and with collar head reinforcement on both sides of the column towards the opening (horizontal) No 2, and fourth specimen with presence of openings adjacent to the column and with collar shear head reinforcement on both sides of the column away from the opening (vertical) No3, fifth specimen with presence of opening and with collar headreinforcement in all sides the column and extend to the opening No 4. The percentage of cracking load to ultimate load capacity was between (40 –48.5)%. By using collar shearhead around the column sides and extended to the opening, the cracking load can be increased to 100% . In flat plate with opening, the deflection and crack width can be decrease by using collar head around the column and extend to the opening and by increasing the compressive strength of concrete of the section.. The slabs which had openings adjacent to the column but strengthened with collar head, the percentage of the critical section perimeter was between (107.5 – 128.3) % that was reflected to the capability of this type of shear reinforcement(collar head) in compensation the shortfall in the critical section due to the existence of openings.. Keywords: key words, flat plate , high strength , opening DOI : 10.7176/CER/11-8-05 Publication date :September 30 th 2019

Shear strengthening of damaged reinforced concrete beams with Hybrid Composite Plates

This paper aims to evaluate experimentally the potentialities of Hybrid Composite Plates (HCPs) technique for the shear strengthening and repairing of reinforced concrete (RC) beams. HCP is a thin plate of Strain Hardening Cementitious Composite (SHCC) reinforced with Carbon Fiber Reinforced Polymer (CFRP) laminates. For this purpose, an experimental program composed of four Rectangular and five T-cross section beams was executed to assess the strengthening efficiency of HCPs technique. There were two control beams without any type of shear reinforcement, and seven beams strengthened with HCPs. The HCPs were applied to the lateral faces of the beams by using a combination of epoxy adhesive and mechanical anchors. The bolts were applied with a certain torque in order to increase the concrete confinement. To have a better understanding of the shear behavior of SHCC material, Iosipescu shear tests were carried out, and the results were used to derive their fracture mode II parameters.To further explore the potentialities of the HCPs technique for the shear strengthening, the experimental tests were simulated numerically by a FEM-based computer program considering the material properties obtained experimentally. After demonstration of the good predictive performance of the numerical model, a parametric study was executed to investigate the influence of some parameters on the load carrying capacity of the strengthened beams, namely: i) Use a mortar instead of the SHCC; ii) application of different applied torque level to the mechanical anchors; iii) different bond condition between HCPs and concrete substrate.

Evaluation of Shear Capacity of Wide Beam Reinforced with Shear Plates with Openings

In this paper, shear behavior of concrete wide beam reinforced with plates with openings was evaluated. For this evaluation, evelen specimens were manufactured. One specimen was non-shear reinforced, five specimens were reinforced with steel plates and the other five specimens were reinforced GFRP plates. Shear strengths measured through experiments were compared with ones calculated from the equation provided by ACI 318. Longitudinal spacing of shear reinforcement, transverse spacing of shear reinforcement and shear reinforcement material were considered as variables. Test results showed that the shear strength increased as the transverse and longitudinal spacing of shear reinforcement became narrow. Also, regardless of material type of shear reinforcement, the shear capacity was similar when the amount of shear reinforcement was the same.

Effect of using swimmer bars on the behavior of normal and high strength reinforced concrete beams

Abstract Shear failure of RC beams is often sudden and catastrophic. The shear cracks progress rapidly without warning, and the diagonal cracks are considerably wider than the flexural cracks. In this study, two types of shear reinforcement are used, traditional stirrups and swimmer bars. Swimmer bar system is a new type of shear reinforcement defined as inclined bars welded to longitudinal top and bottom bars. High strength concrete is a more brittle material than normal strength concrete, and the cracks that form in high strength concrete will propagate more extensively than in normal strength concrete. Ten beams are tested, and the main variables investigated were two different shapes of swimmer bars in addition to traditional stirrups, number of swimmer bar planes, and compressive strength of concrete. The test results will be presented and discussed in order as deflection, ultimate loads, ultimate shear stress, cracking stress and failure modes. Moreover, shear strain is calculated.

THE USE OF SWIMMER BARS AS SHEAR REINFORCEMENT IN REINFORCED CONCRETE BEAM

The behavior of reinforced concrete beams at failure by shear is distinctly different from their behavior by bending, which is considered to be unsafe mode of failure. The shear failure of beams is usually sudden without sufficient advanced warning and the diagonal cracks that develop due to excess shear forces are considerably wider than the flexural cracks. The cost and safety of shear reinforcement in reinforced concrete beams led to the study of other alternatives. Swimmer bar system is a new type of shear reinforcement. It is a small inclined bars, with its both ends bent horizontally for a short distance and welded to both top and bottom flexural steel reinforcement. Regardless of the number of swimmer bars used in each inclined plane, the swimmer bars form plane-crack interceptor system instead of bar-crack interceptor system when stirrups are used. Test results of several reinforced concrete beams will be presented. The effectiveness of the new swimmer bar system as related to the old stirrup system will be discussed. Beam deflection is also targeted experimentally in the lab. Several deflection measurements were taken to study the effect of using new swimmer bar system on deflection. Also the crack width of the tested reinforced concrete beams was monitored.

Shear behavior of continuous reinforced concrete T-beams using wire rope as internal shear reinforcement

The use of wire ropes with high-strength and high flexibility as internal shear reinforcement can solve the difficulties encountered in bending higher strength steel bar and can provide a better shear behavior to concrete beams. Three two-span reinforced concrete T-beams were tested to failure in order to examine the possibility of the practical application of wire ropes as shear reinforcement. The measured shear capacities of beams were compared with predictions obtained from equations specified in ACI 318-08 and the mechanism analysis based on the upper-bound theorem of concrete plasticity. Test results showed that using spiral-type wire rope as shear reinforcement is highly favourable for controlling the diagonal crack width and enhancing the ductility of beams failing in shear. In particular, the high-strength of the wire ropes significantly promoted the shear capacity of concrete beams. When a limit stress of 420 MPa for wire ropes is employed, ACI 318-08 is highly conservative in beams with spiral-type wire ropes compared with the control beams with closed stirrups. In addition, ACI 318-08 is still conservative when using the equivalent yield strength of wire ropes. On the other hand, the predictions obtained from the mechanism analysis are in good agreement with test results, regardless of the type of shear reinforcement.

유효 스터럽 개념을 이용한 전단보강근의 강도 예측

This paper presents the prediction of the actual strength of shear reinforcement on the basis of the concept of effective stirrups. The prediction method incorporating the shear cracking angle was proposed with the estimation by the Modified Compression Field Theory (MCFT). To check the validity of the method, discussion of the current ACI 318-05 and comparison of 39 test results from the literature including author`s retrospective test data were made. The influencing factors of compressive concrete strength and type of shear-reinforcement were also investigated. Furthermore, two full-scale beam specimens shear-reinforced with headed bars were tested to demonstrate the applicability of the proposed method.

Failure analysis of column–slab connections with stud shear reinforcement

The design of a flat plate structure is generally governed either by serviceability limits on deflection or punching shear strength of the column–slab connections. To increase the strength of a column–slab connection, a new type of shear reinforcement, referred to as shear stud, is gaining popularity in practice. In this paper, a nonlinear layered finite element method (LFEM) is used to investigate the effectiveness of the shear studs in increasing the punching shear strength of edge and corner column–slab connections. In total, nine large-scale reinforced concrete slabs of a flat plate floor in the vicinity of edge and corner columns, tested previously in the laboratory, are analysed. All the slabs contained stud shear reinforcement (SSR) except a control slab where no SSR was provided. The test variables were the column size and the ratio of stud spacing to slab thickness. The punching shear strengths, load–deflection responses, and crack patterns predicted by the LFEM are compared with the experimental results. The numerical investigation confirms the accuracy and effectiveness of the LFEM in predicting the strength of column–slab connections with SSR.Key words: column–slab connection, concrete flat plate, punching shear, stud shear reinforcement, finite element analysis.

Shear Reinforcement for Concrete Slabs

A review of the different types of shear reinforcement for concrete flate plates is presented and the difficulties encountered when these are used in practice are reviewed. Practical shear reinforcement should efficienty increase the shear strength and ductility of the slab-column connection, and should be easy to fabricate and install. New Type of shear reinforcement which satisfies these requirements is presented. An individual reinforcing element is in the form of vertical bars with mechanical anchorages at the two ends. The size and shape of the anchors are examined as well as the arrangement of the shear elements around the column. From the results of 40 full-size tests, rules for the design of the new type of shear reinforcement are given in the form of suggested revisions to the current codes.