Behaviour of flexural plastic hinges under high seismic shear with consideration of concrete strength

2009 ◽  
Vol 36 (11) ◽  
pp. 1711-1721 ◽  
Author(s):  
Abdelsamie Elmenshawi ◽  
Tom Brown ◽  
Robert Loov
Keyword(s):  
Shear Strength ◽  
Shear Failure ◽  
Concrete Strength ◽  
Shear Behaviour ◽  
Experimental Program ◽  
Concrete Element ◽  
Shear Deformations ◽  
Plastic Hinges ◽  
Cyclic Shear ◽  
Seismic Shear

A successful seismic design for a reinforced concrete element is one that can postpone the shear failure until the required ductility and deformation capacity are obtained. After flexural yielding, shear deformations are the main causes for strength and stiffness degradation. An experimental program was carried out to explore the shear behaviour of flexural plastic hinges of elements constructed with different concrete strengths (30–175 MPa) tested under load reversals. The specimen represented a beam–column assembly and was designed to have the inelastic deformation at the beam end only. The research investigated the effect of shear deformations on the hysteretic behaviour and stiffness deterioration, cyclic shear demands, shear resisting mechanisms, and the effect of concrete strength on the hinge shear strength. It was found that the effect of concrete strength on beam shear strength under cyclic loading differs from that under unidirectional loading.

scholarly journals Shear tests on GFRP reinforced concrete beams

2020 ◽  
Vol 323 ◽  
pp. 01009
Author(s):  
Damian Szczech ◽  
Renata Kotynia
Keyword(s):  
Failure Modes ◽  
Shear Failure ◽  
Concrete Beams ◽  
Reinforcement Ratio ◽  
Reinforced Concrete Beams ◽  
Shear Behaviour ◽  
Experimental Program ◽  
Glass Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Glass Fibre Reinforced

This paper aims to investigate the shear failure mechanisms in beams reinforced with longitudinal and transverse glass fibre reinforced polymer bars. It is a part of comprehensive research on shear in concrete beams reinforced with steel and GFRP bars. The experimental program is composed of six real-scale single-span, simply-supported T-cross section concrete beams. The beams varied mainly with respect to the longitudinal reinforcement ratio (2.91% and 3.69%), bar diameter (25mm and 28mm, respectively) and transverse reinforcement ratio (0.16% and 0,33%). The paper presents test results, cracking patterns, failure modes and an analysis of the influence of variable parameters on the shear behaviour of elements.

SHEAR MECHANISM AND SHEAR STRENGTH PREDICTION OF REINFORCED CONCRETE T-BEAMS

2016 ◽  
Vol 78 (5) ◽  
Author(s):  
Abdul Aziz Abdul Samad ◽  
Noridah Mohamad ◽  
Mohammed Anwar Hail al-Qershi ◽  
J. Jayaprakash ◽  
Priyan Mendis
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Shear Failure ◽  
Reinforced Concrete Beam ◽  
Reinforced Concrete Beams ◽  
Bending Test ◽  
Shear Behaviour ◽  
Design Codes ◽  
Shear Mechanism ◽  
Strength Capacity

Shear failure in reinforced concrete beams are sudden failures and should be avoided at all times. However, the shear behaviour of a reinforced concrete beam is a complex mechanism and requires in-depth study. To understand the shear mechanism, two (2) simply supported reinforced concrete T-beams, BEAM1 and BEAM2 were tested until failure subjected to a 4-point bending test. Both beams were designed to the recommendations and specifications of two (2) established design codes by ACI318-08 and Eurocode2 (EC2). The study comprises of two reinforced concrete T-beams having similar variables and parameters with longitudinal reinforcement of ρ = 2.15% and shear span-to-effective depth ratio (av/d) of 3.5. Shear reinforcement or stirrups has been added to the specimen and its spacing of stirrups has been provided with the provisions of the codes. The findings from the study indicate that ACI318-08 and EC2 design codes shows significant differences in determining its shear strength capacity Vn and concrete shear resistance Vcof the T-beams. However, both results were less conservative in its prediction when compared to the experimental results. 

scholarly journals Shear strength of brick mortar interface for masonry in Lima city

2019 ◽  
Vol 29 (2) ◽  
Author(s):  
Luis Lavado ◽  
Jorge Gallardo
Keyword(s):  
Shear Strength ◽  
Compressive Stress ◽  
Shear Failure ◽  
Pure Shear ◽  
Load Level ◽  
Experimental Program ◽  
Masonry Walls ◽  
Loading Test ◽  
Compression Load ◽  
Building Inventory

Masonry structures constitute a large proportion of the building inventory in Lima and in most cities in Peru, mainly because of their benefits in terms of low cost, good mechanical properties and easily worked. It was observed in the cyclic loading test of masonry walls carried out at CISMID that the modes of failures can be mainly generated by shear forces. Based on the previous information, it is known that diagonal cracking and slip of the mortar-brick joints are the dominant failure mechanisms of confined masonry walls.  In order to determine the mechanical behavior in the mortar-brick joint, an experimental program was carried out, by using industrial and handmade bricks. The test specimens were specifically designed to transmit pure shear along the bed joints under certain constant levels of compressive stress normal to the bed joint. The results of experimental shear tests are presented and discussed. It is then found a consistency between the behavior of masonry joints under shear with the Mohr Coulomb criterion. The shear failure capacity was influenced by the brick type, pre-compression load level and mortar type. It is also noticed in this experimental study that the pre-compressive stress normal to the bed joints significantly increase the shear strength of the mortar-brick joint.

scholarly journals Shear strength of steel–concrete–steel sandwich deep beams: A simplified approach

2018 ◽  
Vol 22 (1) ◽  
pp. 42-53 ◽  
Author(s):  
Yubing Leng ◽  
Xiaobing Song
Keyword(s):  
Shear Strength ◽  
Analytical Model ◽  
Failure Modes ◽  
Shear Failure ◽  
Concrete Strength ◽  
Upper And Lower Bounds ◽  
Deep Beams ◽  
Concrete Core ◽  
Simplified Approach ◽  
Triangular Area

Steel–concrete–steel composite structure comprises a concrete core sandwiched between the outer steel plates. It combines the advantages of both steel and reinforced concrete structures. In thick steel–concrete–steel structural members, the shear performance becomes rather critical. Experimental works have been carried out to study the failure mode and shear strength of steel–concrete–steel deep beams, and an analytical model has been proposed. In this article, parametric studies are carried out on the original analytical model to discuss the influence of each geometric and material variable on the shear strength, and a simplified strength predicting method is developed. Different shear failure modes, identified as “top+bottom triangular area damage” or “bottom triangular area damage+horizontal cracking,” can be predicted with the method. The simplified approach shows good correlation with the experimental results, regarding to shear resisting pattern and failure modes. Through the simplified formulas, the upper and lower bounds of the shear resistance are obtained. The requirement on stud spacing to maintain full composite behavior in the top and bottom triangular areas and the requirement on concrete strength are proposed.

scholarly journals Effect of Particle-Size Gradation on Coarse Sand-Geotextile Interface Response in Cyclic and Postcyclic Direct Shear Test

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Jun Wang ◽  
Meng-Jie Ying ◽  
Fei-Yu Liu ◽  
Hong-Tao Fu ◽  
Jun-Feng Ni ◽  
...  
Keyword(s):  
Particle Size ◽  
Shear Stress ◽  
Shear Strength ◽  
Shear Behaviour ◽  
Direct Shear ◽  
Interface Shear ◽  
Cycle Number ◽  
Cyclic Shear ◽  
Stress Degradation ◽  
Particle Size Gradation

In order to investigate the influence of sand particle-size gradation on cyclic and postcyclic shear strength behaviour on sand-geotextile interfaces, a series of monotonic direct shear (MDS), cyclic direct shear (CDS), and postcyclic direct shear (PCDS) tests were performed using a large-scale direct shear apparatus. The influence of cyclic shear history on the direct shear behaviour of the interface was studied. The results indicated that cyclic shear stress degradation occurred at the sand-geotextile interface. Shear volumetric contraction induced by the cyclic direct shear increased with the increase in cycle number. The lowest final contraction value was observed in discontinuously graded sand. In the MDS tests, there were great differences in interface shear strength due to the different particle-size gradations, whereas the differences between shear volumes were negligible. In the PCDS tests, the shear stress-displacement curves exhibited postpeak stress hardening behaviour for different particle-size gradations, and differences in shear volumes were detected. The well-graded sand-geotextile interface had a higher value of shear stiffness and a higher damping ratio relative to the other interfaces. Postcyclic shear stress degradation was observed for the discontinuously graded sand-geotextile interface.

scholarly journals Experimental Study on Mechanical Properties of Interface between Basalt Fiber-Reinforced Polymer/Glass Fiber-Reinforced Polymer Composite Cement Plate and Concrete

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Lifeng Zhang ◽  
Hui Liu ◽  
Wenqiang Li ◽  
Hangjun Liu ◽  
Xuehui An ◽  
...  
Keyword(s):  
Shear Strength ◽  
Failure Modes ◽  
Shear Failure ◽  
Concrete Strength ◽  
Concrete Block ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Bond Slip ◽  
Reinforced Polymer ◽  
Composite Samples

The bonding behaviors of the plate-concrete interface of a composite structure consisting of a concrete block in the middle and two cement plates at both sides play a key role in its overall mechanical performance. In this paper, the authors conduct 3 groups of push-out shear tests on a total of 39 composite samples to assess the bonding performance. The influence of the FRP cement plates, the concrete strength, and the ribs installed in the cement plate on the interfacial shear strength, the relative bond-slip, strain, and the failure modes of the composite samples is recorded and analyzed. The results show that (1) the shear strength and bond-slip performance of the interface are largely improved if the GFRP/BRRP cement plates are used; (2) shear strength of the interface increases with the concrete strength, while the deformation behaviors show no significant improvement; (3) an inclusion of the ribs to the interface enhances the shear strength and shear stiffness but decreases the maximum relative slip at failure; (4) most of the samples present the shear failures along the interface; however, the bending shear failure prior to the interface shear failure is also observed on the concrete block for low concrete strength samples and the samples with ribs; and (5) regression method is used to develop a constitutive model of the stress-slip at the interface to describe the relationship between the shear strength with the cement plates, the concrete strength, and ribs.

scholarly journals Numerical Simulation of the Shear Behaviour of Cement Grout

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Jianhang Chen ◽  
Fan Zhang ◽  
Hongbao Zhao ◽  
Junwen Zhang
Keyword(s):  
Shear Stress ◽  
Shear Strength ◽  
Stress Distribution ◽  
Normal Stress ◽  
Shear Failure ◽  
Cement Grout ◽  
Shear Stress Distribution ◽  
Shear Behaviour ◽  
Direct Shear ◽  
Failure Plane

Cement grout is widely used in civil engineering and mining engineering. The shear behaviour of the cement grout plays an important role in determining the stability of the systems. To better understand the shear behaviour of the cement grout, numerical direct shear tests were conducted. Cylindrical cement grout samples with two different strengths were created and simulated. The numerical results were compared and validated with experimental results. It was found that, in the direct shear process, although the applied normal stress was constant, the normal stress on the contacted shear failure plane was variable. Before the shear strength point, the normal stress increased slightly. Then, it decreased gradually. Moreover, there was a nonuniform distribution of the normal stress on the contacted shear failure plane. This nonuniform distribution was more apparent when the shear displacement reached the shear strength point. Additionally, there was a shear stress distribution on the contacted shear failure plane. However, at the beginning of the direct shear test, the relative difference of the shear stresses was quite small. In this stage, the shear stress distribution can be assumed uniform on the contacted shear failure plane. However, once the shear displacement increased to around the shear strength point, the relative difference of the shear stresses was obvious. In this stage, there was an apparent nonuniform shear stress distribution on the contacted shear failure plane.

scholarly journals Research on the Mechanism of the Influence of Earthquake-Induced Landslides on the Stress and Deformation Characteristics of Tunnel

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Yufang Zhang ◽  
Hongyu Liu ◽  
Jian Li ◽  
Qidi Huang ◽  
Xianjie Ma ◽  
...  
Keyword(s):  
Shear Failure ◽  
Concrete Strength ◽  
Weak Links ◽  
Tunnel Structure ◽  
Railway Tunnel ◽  
Supporting Structure ◽  
Limit Value ◽  
Seismic Shear ◽  
The Right ◽  
The Impact

The landslide at the entrance of a railway tunnel in the southwestern region is relatively large, especially due to earthquakes and other factors, which are prone to severe disasters and threaten the safety of the tunnel. Through the long-term monitoring test and numerical calculation analysis on-site, the mechanism of the influence of the earthquake-induced landslide on the characteristics of the tunnel’s force and deformation is studied. The research results show that the earthquake caused the landslide thrust to increase. Because of the existence of the supporting structure, the landslide thrust was consumed, and the remaining part resulted in the compression failure of the tunnel. During the seismic monitoring period, the stress loss of the antislide pile anchor cable was 3.73% and the stress of the second lining of the tunnel increased by 25%. Under the condition of extreme seismic, shear failure occurred at the vault, bottom, and waist of the right-line tunnel, and the tensile strength of the right-line tunnel reached 93.8% of the limit value. For the weak links of the tunnel structure, dense reinforcement planting and strengthening of concrete strength should be adopted to enhance the safety of the tunnel structure. While designing the supporting structure, the rock-socketing depth of the antislide piles and the number of antislide piles should be considered a priority. The impact of the antislide pile spacing is relatively small.

scholarly journals The Influence of CFRP Orientation Angle on the Shear Strength of RC Beams

2018 ◽  
Vol 12 (1) ◽  
pp. 269-281 ◽  
Author(s):  
Yasmin Murad
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Experimental Studies ◽  
Orientation Angle ◽  
Shear Behaviour ◽  
Experimental Program ◽  
Rc Beams ◽  
Cfrp Sheets ◽  
Reinforced Polymer ◽  
Cfrp Sheet

Background:Carbon Fiber Reinforced Polymer (CFRP) sheets are widely used for strengthening and repairing reinforced concrete structures. Previous experimental studies have shown that strengthening Reinforced Concrete (RC) beams with CFRP sheet can be greatly influenced by the configuration, orientation and properties of the CFRP sheets.Objective:The behaviour of RC beams, strengthened with 60° and 45° inclined CFRP sheets, has not clearly explained.Method:Thus, an experimental program, proposed in this paper, investigates the shear behaviour of RC beams strengthened with CFRP sheets under different orientation angles including 0˚, 45˚, 60˚ and 90˚.Result:The study shows that strengthening RC beams with CFRP is highly influenced by the orientation angle of the sheets. The influence of CFRP sheets is remarkable on increasing the ultimate deflection, ductility and shear strength of RC beams.Conclusion:It is beneficial to strengthen RC beams, which are weak in shear, obliquely using 45˚ or 60˚ inclined CFRP sheets.

Reinforced concrete beams without stirrups considering shear friction and fracture mechanics

2006 ◽  
Vol 33 (2) ◽  
pp. 161-168 ◽  
Author(s):  
M T Kazemi ◽  
V Broujerdian
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Fracture Mechanics ◽  
Shear Failure ◽  
Concrete Beams ◽  
Concrete Strength ◽  
Shear Capacity ◽  
Reinforced Concrete Beams ◽  
Maximum Aggregate Size ◽  
Aggregate Interlock

A new expression for the shear capacity of reinforced concrete beams without stirrups was derived by calculating the aggregate interlock capacity across the major diagonal crack of the beam, a procedure somewhat similar to those based on the modified compression field theory. Two formulas were obtained from the simplification of this expression. All three relations capture the dependence of shear strength on the size of the beam, the ratio of shear span to beam depth, longitudinal reinforcement ratio, maximum aggregate size, and concrete strength. The limits of these formulas agree well with the limit solutions of shear failure load for very small and very large beams based on plastic and fracture mechanics solutions, respectively. The proposed relations were calibrated by least-squares fitting of the existing experimental database (consisting of 398 data points) and resulted in low coefficients of variation. The simplest version is suitable for design codes.Key words: reinforced concrete, shear strength, beams, aggregate interlock, crack opening, size effect.

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