Strength deterioration of reinforced concrete beam–column joints subjected to cyclic loading (original) (raw)
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International journal of engineering research and technology, 2020
This paper is concerned with experimental study of exterior reinforced beam-column joints subject to reverse cyclic loading. Four full scale beam-column joints (had the same moment of inertia) with concrete grade 35 Mpa were tested under reversed cyclic loading, applied in quasi-static cyclic condition, to study the effect of different column shapes on the behavior of reinforced concrete beam-column Joints, The results showed that all joints exhibited the same failure mode at the interface between beam and column, rectangular column (with same width of beam) and squared column shape were higher than the regular rectangular column and circular column in the loading capacity, displacement, stiffness degradation and strength decay.
Behaviour of reinforced high-strength concrete beam—column joint. Part 1: experimental investigation
Structural Concrete, 2003
The beam-column joint is one of the important structural elements of reinforced concrete structures. It has been the subject of intensive research for the past four decades. To date, most of the design procedures of joints have been devoted to ordinary-strength concrete as implemented in the current international design codes. The use of high-strength concrete has become useful because of the advantages of member size limitation and higher structural capacity. However, its applicability is still limited because its behaviour, especially under combined stresses and shear, differs from ordinary-strength concrete in the presence of axial loading on the column. Consequently, the existing design guidelines are not completely applicable. In order to establish the salient features of the behaviour, namely modes of failure, deformational characteristics, strength parameters and strain development, an experimental programme was performed on beam-column joints under quasi-static monotonic loading. The influence of axial compression, along with other actions imposed on the joint including shear and bending moment, was taken into consideration. The practical aspects of using a composite structure-that is, ordinary-strength concrete of different grades at floor level and high-strength concrete along the rest of the column-were considered. The effects of different permutations of longitudinal as well as transverse reinforcement and various configurations of stirrups were also investigated.
International Journal of Engineering Research and Technology (IJERT), 2020
https://www.ijert.org/effect-of-column-shape-on-the-behavior-of-reinforced-concrete-beam-column-joints-under-quasi-static-loading https://www.ijert.org/research/effect-of-column-shape-on-the-behavior-of-reinforced-concrete-beam-column-joints-under-quasi-static-loading-IJERTV9IS090478.pdf This paper is concerned with experimental study of exterior reinforced beam-column joints subject to reverse cyclic loading. Four full scale beam-column joints (had the same moment of inertia) with concrete grade 35 Mpa were tested under reversed cyclic loading, applied in quasi-static cyclic condition, to study the effect of different column shapes on the behavior of reinforced concrete beam-column Joints, The results showed that all joints exhibited the same failure mode at the interface between beam and column, rectangular column (with same width of beam) and squared column shape were higher than the regular rectangular column and circular column in the loading capacity, displacement, stiffness degradation and strength decay.
Shear Strength Degradation Due to Ductility Demand in R.C. Columns and Beams
2016
A clear distinction can be made between brittle shear failure, occurring before the flexural strength of the column has been attained, ductile shear failure that occurs after that a flexural plastic hinges has been activated, and plastic rotations increased. The shear strength reduction is due to degrading of several resisting mechanism:aggregate interlock due to reduction of the roughness of the crack surface by the smoothing action of the cyclic load, and bond slippage; dowel action due to cover rupture, hoops and longitudinal rebar plastic strain, and eventually buckling of the latter; strength of chord and web concrete due to compression softening and development of cracking for cyclic load. Several studies addressed the shear strength reduction due to ductility demand on the basis of smeared cracking non-linear models, such as the Modified Compression Field Theory (MCFT). However, despite their success in modeling several structural type behaviors, they do not appear suitable t...
Cyclic Behavior of Substandard Reinforced Concrete Beam-Column Joints with Plain Bars
ACI Structural Journal, 2013
An experimental investigation aimed at assessing the cyclic behavior of substandard interior beam-column joints built with plain reinforcing bars is described in this paper. Five specimens with plain reinforcing bars and one with deformed bars were tested under reversed cyclic loading. The influence of bond properties, displacement history, column axial load, and amount of reinforcement was investigated. A comparison was established in terms of maximum strength, damage, energy dissipation, ductility, displacement components, and rotation capacity. Better bond properties led to a more spread damage distribution and larger energy dissipation. Higher column axial load resulted in larger lateral strength and energy dissipation. A larger amount of longitudinal and transverse reinforcement did not necessarily lead to enhanced behavior. The test results contribute to the characterization of the cyclic behavior of beam-column joints with plain bars and can be used to calibrate numerical models for the simulation of this type of element.
Procedia Engineering, 2016
This paper investigates the key influence factors for the shear strength of both exterior and interior reinforced concrete (RC) beam-column joints. A database of totally 172 experimental RC beam-column connections constructed using the published literature was used in the analysis. Based on the database, the correlation coefficient (CC) between the considered parameters and the tested joint shear strength was computed, and the important level of these parameters was quantified. Results of the analysis showed that five key parameters for the joint shear strength included (1) the concrete compressive strength, (2) the vertical joint shear reinforcement, (3) the beam bars detail index, (4) the horizontal joint shear reinforcement and (5) the column axial stress. Among the influence factors, the concrete compressive strength had the most significant correlation to the joint shear strength and interestingly its correlation was higher for the interior connections with CC = 0.8 compared to CC = 0.69 for the exterior connections. For the remaining factors, the analysis conversely showed that their correlations to the joint shear strength of exterior joint were stronger than that of the interior joint.
Reinforced concrete beam–column joints with crossed inclined bars under cyclic deformations
Earthquake Engineering & Structural Dynamics, 2008
This experimental study investigates the effectiveness of crossed inclined bars (X-bars) as joint shear reinforcement in exterior reinforced concrete beam-column connections under cyclic deformations. Test results of 20 joint subassemblages with various reinforcement ratios and arrangements including X-bars in the joint area are presented. The X-type, non-conventional reinforcement is examined as the only joint reinforcement and in combination with common stirrups or vertical bars. The experimental results reported herein include full loading cycle curves, energy dissipation values and a categorization of the observed damage modes. Based on the comparisons between the overall hysteretic responses of the tested specimens, it is deduced that joints with X-bars exhibited enhanced cyclic performance and improved damage mode since a distinct flexural hinge was developed in the beam-joint interface. Further, the combination of crossed inclined bars and stirrups in joint area resulted in enhanced hysteretic response and excellent performance capabilities of the specimens. However, in some specimens with X-bars as the only joint shear reinforcement, the deformations of the bent anchorage of the beam's bars caused considerable damages at the back of the joint area. Discussion for a potential replacement of the joint stirrups with X-type reinforcement in some cases of exterior joints is also included.
International Journal for Research in Applied Science & Engineering Technology (IJRASET), 2022
The beam-column joint is measured as the most important zone in a reinforced concrete moment resisting frame. It is subjected to large forces during earthquake and its behaviour has a major influence on the response of the entire structure. As a result, a great attention has to be paid for good detailing of such joint. The absence of transverse reinforcement in the joint, insufficient development length for the beam reinforcement and the inadequately spliced reinforcement for the column just above the joint can be considered as the most important causes for the failure of the beam-column joint under any unexpected transverse loading on the building. The recent earthquakes revealed the importance of the design of reinforced concrete (RC) structures with ductile behaviour. Ductility can be described as the ability of reinforced concrete cross sections, elements and structures to absorb the large energy released during earthquakes without losing their strength under large amplitude and reversible deformations.
Performance evaluation of differently designed beam-column joints under cyclic shear-torsion loading
Engineering Structures, 2019
To evaluate the performance of reinforced concrete beam-column joints, two different types of exterior beamcolumn joints i.e. (gravity load designed and ductile designed) are considered. First, shear strength of the joints (representing two different types of reinforcement distribution) is analytically evaluated using softened strut and tie model. To check the performance of the joints under shear and coupled shear-torsion loading, experimental investigations on the beam-column joints under reverse cyclic loading are carried out. The important behaviour parameters such as load-displacement hysteresis, energy dissipation, damage formation and strength and stiffness degradation are evaluated. It is found that the analytical prediction of shear strength of the differently designed beam-column joints is very close. Further, it is emphasized that the torsion loading has a significant detrimental effect on the degradation behaviour of the beam-column joints, specifically on those which are under-designed. From the study, it is found that the energy dissipation corresponding to per cycle drift provides much better insight than that from cumulative energy dissipation. It is also found that structural behaviour parameters such as strength, stiffness and shear deformation provide very important and complementary information for evaluating the performance of joints under coupled shear-torsion.
BEHAVIOUR OF BEAM-COLUMN JOINT UNDER CYCLIC LOADING
Beam-column joints of a reinforced concrete structure need special attention due to their highly complex behavior under seismic loads, which is marked by a combination of large shear forces, diagonal tension and high bond stresses in the reinforcement bars, all brittle mode of failure. This paper presents an experimental behavior of beam-column joints under cyclic loading. Four numbers of exterior beam-column joint specimens were cast and tested under cyclic loading. The specimens were designed for seismic load according to IS 1893(Part-I):2002 and IS 13920:1993. The test specimens were evaluated in terms of load-displacement relation, and cracking pattern.