scholarly journals A Review on the Plastic Hinge Characteristics of Beam-Column Joints in RC Moment Resisting Frames

2021 ◽  
Author(s):  
Surya SS ◽  
R Sajeeb
Keyword(s):  
Plastic Hinge ◽  
High Strength ◽  
Joint Interface ◽  
Careful Study ◽  
Plastic Hinges ◽  
Moment Resisting Frames ◽  
Extreme Loads ◽  
Moment Resisting ◽  
Column Joint ◽  
Joint Behavior

The behavior of beam-column joints plays a crucial role in the performance of Reinforced Concrete (RC) moment-resisting frames in earthquake-prone areas. In beam-column joints with high strength concrete and shear reinforcement in joints, the plastic hinge is formed at the beam-column joint interface, which is an undesirable failure mode. Predicting the behavior of plastic hinges subjected to large inelastic deformations caused by extreme loads such as earthquake plays an important role in assessing maximum stable deformation capacities of framed concrete structures. The present paper reviews the plastic hinge characteristics of beam-column joints of RC moment-resisting frames. A careful study and understanding of joint behavior are essential to arrive at a proper judgment of the design of joints. Various types of joints and the influence of bond strength characteristics, forces acting on joints, reinforcement detailing, and the concept and formation of plastic hinges in the joints are thoroughly reviewed.

Plastic hinge relocation in reinforced concrete beam–column joint using carbon fiber–reinforced polymer

2019 ◽  
Vol 22 (14) ◽  
pp. 2951-2965 ◽  
Author(s):  
Olaniyi Arowojolu ◽  
Ahmed Ibrahim ◽  
Muhammad K Rahman ◽  
Mohammed Al-Osta ◽  
Ali H Al-Gadhib
Keyword(s):  
Carbon Fiber ◽  
Plastic Hinge ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Joint Interface ◽  
Fiber Reinforced ◽  
Reinforced Polymer ◽  
Moment Resisting ◽  
Column Joint ◽  
Carbon Fiber Reinforced

Reinforced concrete buildings with moment-resisting frames comprising beam–column joints (without joint shear reinforcement) designed prior to introduction of seismic codes are shear deficient when subjected to seismic loading, thereby mostly fail in shear at the core of the beam–column joint. However, those designed to the new seismic codes may fail by flexural hinging at the interface of the beam–column joint due to the yielding of the beam reinforcement at the location of highest stress demand (usually the beam–column joint interface). The shear failure has been precluded through the provision of transverse reinforcement at the joint in new design and the use of carbon fiber–reinforced polymer retrofitting in old buildings. Plastic hinge formation at the interface of the beam–column joint is critical because of its penetration into the joint and its effect on bond deterioration. In this study, eight corner-external beam–column joint specimens of 1/3 scale of a typical moment-resisting frame, made without transverse reinforcement, were tested for monotonic and reversed cyclic test under displacement-controlled regime. The control specimens failed by flexural hinging at the beam–column joint interface. The experimental results have been validated using the finite element model. The specimens were retrofitted with unidirectional carbon fiber–reinforced polymer of different layers and different length. After retrofitting, the plastic hinge was relocated to the curtailment end of the carbon fiber–reinforced polymer. The relocation of the plastic hinge resulted in higher load capacity and ductility.

Behaviour of dual eccentrically braced steel frames with short and long seismic links

2019 ◽  
Author(s):  
Ivan Lukačević ◽  
Tomislav Maleta ◽  
Darko Dujmovic
Keyword(s):  
Energy Dissipation ◽  
Plastic Hinge ◽  
Seismic Energy ◽  
High Strength ◽  
Elastic Behaviour ◽  
Braced Frame ◽  
Moment Resisting Frames ◽  
Collapse Mechanisms ◽  
Moment Resisting ◽  
Flexible Part

<p>Dual structures obtained by combining moment resisting frames with innovative bracing systems such as replaceable shear panels or seismic links have significant advantages among conventional solutions. The major advantages of such systems are energy dissipation in the specific locations and re-centring capability which significantly reduces repair costs. On the other hand, design of such systems is driven with specific requirements such as combining different steel grades to ensure elastic behaviour of the flexible part of the system. This paper deals with comparative behaviour analyses of two dual systems combining moment resisting multi-storey frames with eccentric bracing systems. The steel frame consists of three bays with central braced frame and two adjacent moment resisting frames. The bracing system contains either long or short seismic link. Seismic energy dissipation of these systems is completely different. Long seismic links are characterised with a classical plastic hinge in which energy is dissipated through bending while in case of short seismic links seismic energy is dissipated through shear. Multi-linear plastic diagrams for both links have been defined and pushover analyses are performed. The behaviour of the analysed systems based on collapse mechanisms, overstrength ratio, target displacement and possible solutions for re-centring capabilities are discussed. Analysed system with short seismic links despite more complicated modelling and requirements for high strength steel in MRFs, results in higher overstrength ratio regarding the system with long seismic links. It is also far easier to dismantle system with short seismic links, due to the bolted connection of links with the adjacent members.</p>

scholarly journals Some possible revisions to the seismic provisions of the New Zealand concrete design code for moment resisting frames

1992 ◽  
Vol 25 (1) ◽  
pp. 37-43
Author(s):  
P. C. Cheung ◽  
T. Paulay ◽  
R. Park
Keyword(s):  
Reinforced Concrete ◽  
New Zealand ◽  
Plastic Hinge ◽  
Design Code ◽  
Concrete Frames ◽  
Rational Models ◽  
Moment Resisting Frames ◽  
Moment Resisting ◽  
Column Joint ◽  
Experimental And Theoretical Studies

Possible revisions to the seismic design provisions of the New Zealand concrete design code NZS 3101: 1982 for ductile reinforced concrete moment resisting frames are discussed. Topics include shear reinforcement for beam-column joint cores, anchorage of longitudinal reinforcement passing through beam-column joint cores, and transverse reinforcement in columns for confinement in potential plastic hinge regions of columns. The recommendations are based on recent experimental and theoretical studies of the simulated seismic response of beam-column joints and columns in ductile reinforced concrete frames. Rational models for the evaluation of behaviour are presented.

scholarly journals Ductility demand for uni-directional and reversing plastic hinges in ductile moment resisting frames

1999 ◽  
Vol 32 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Richard Fenwick ◽  
Raad Dely ◽  
Barry Davidson
Keyword(s):  
Plastic Hinge ◽  
Time History ◽  
Simple Relationship ◽  
Plastic Hinges ◽  
Ductility Demand ◽  
Displacement Ductility ◽  
Moment Resisting Frames ◽  
Moment Resisting ◽  
Negative Moment ◽  
Unidirectional Plastic

In a major earthquake the beams in moment resisting frames may develop either reversing or unidirectional plastic hinges. The form of plastic hinge depends upon the ratio of the moments induced by the gravity loading to those induced by the seismic actions. Where this ratio is low the plastic hinges form at the ends of the beams and the sign of the inelastic rotation changes with the direction of sway. These are reversing plastic hinges, and the magnitude of the rotation that they sustained is closely related to the inter-storey displacement. However, when the moment ratio exceeds a certain critical value, unidirectional plastic hinges may form. In this case negative moment plastic hinges develop at the column faces and the positive moment plastic hinges form in the beam spans. As the earthquake progresses the positive and negative inelastic rotations accumulate in their respective zones so that peak values are always sustained at the end of the earthquake. With this type of plastic hinge no simple relationship exists between inter-storey drift and inelastic rotation. Several series of time history analyses have been made to assess the relative magnitudes of inelastic rotation that are imposed on the two forms of plastic hinge. It is found that with design level earthquakes typically the unidirectional plastic hinge is required to sustain 21/ 2 to 4 times the rotation imposed on reversing plastic hinges, with the curvature ductilities ranging up to 140. These values are appreciably in excess of the values measured in tests using standard details. This indicates that in structures where unidirectional plastic hinges may form, the design displacement ductility and or the allowable inter-storey drift should be reduced below the maximum values currently permitted in the New Zealand codes. The problems associated with the formation of unidirectional plastic hinges can be avoided by adding positive moment flexural reinforcement in the mid regions of the beams. By this means the potential positive moment plastic hinges can be restricted to the beam ends.

Effect of Bracing Elements on Mechanics and Shear Strength of Exterior Beam-Column Joints in Moment Resisting Frames

2013 ◽  
Vol 343 ◽  
pp. 15-19
Author(s):  
G. Appa Rao ◽  
S. Kanaka Durga
Keyword(s):  
Shear Strength ◽  
Strength Reduction ◽  
Beam Length ◽  
Optimum Location ◽  
Joint Shear Strength ◽  
Moment Resisting Frames ◽  
Moment Resisting Frame ◽  
Moment Resisting ◽  
Column Joint ◽  
Shear Strength Reduction

Beam-column joint in moment resisting frames is very crucial particularly for non-seismically designed cases, which requires strengthening by various methods. This paper reports on shear strength reduction in exterior beam-column joints using haunch elements. Numerical analysis has been performed on exterior beam-column joint of moment resisting frame with and without a haunch element using SAP software. A parametric study has been performed for optimum haunch location (L) along the beam length (Lb) (10%, 12.5%, 15%, 20%, 25%, 40% and 50% of Lb) and the angle of the haunch element along column axis (15°, 30°, 45° and 60°). It has been observed that the optimum location of the haunch element is at 0.2Lb along the beam at an inclination of 45° with the column axis. The analysis results show that the addition of haunch element significantly reduced the joint shear strength.

scholarly journals Seismic collapse safety of reinforced concrete moment resisting frames with/without beam-column joint detailing

2021 ◽  
Vol 54 (1) ◽  
pp. 1-20
Author(s):  
Naveed Ahmad ◽  
Muhammad Rizwan ◽  
Muhammad Ashraf ◽  
Akhtar Naeem Khan ◽  
Qaisar Ali
Keyword(s):  
Reinforced Concrete ◽  
Ground Motions ◽  
Seismic Intensity ◽  
Shear Reinforcement ◽  
Dynamic Reliability ◽  
Moment Resisting Frames ◽  
Collapse Probability ◽  
Seismic Collapse ◽  
Moment Resisting ◽  
Column Joint

FEMA-P695 procedure was applied for seismic collapse safety evaluation of reinforced concrete moment resisting frames with/without beam-column joint detailing common in Pakistan. The deficient frame lacks shear reinforcement in joints and uses concrete of low compressive strength. Shake-table tests were performed on 1:3 reduced scale two-story models, to understand the progressive inelastic response of chosen frames and calibrate the inelastic finite-element based models. The seismic design factors i.e. response modification coefficient, overstrength, ductility, and displacement amplification factors (R, W0, Rμ, Cd) were quantified. Response modification factor R = 7.05 was obtained for the frame with beam-column joint detailing while R = 5.30 was obtained for the deficient frame. The corresponding deflection amplification factor Cd/R was found equal to 0.82 and 1.03, respectively. A suite of design spectrum compatible accelerograms was obtained from PEER strong ground motions for incremental dynamic analysis of numerical models. Collapse fragility functions were developed using a probabilistic nonlinear dynamic reliability-based method. The collapse margin ratio (CMR) was calculated as the ratio of seismic intensity corresponding to the 50th percentile collapse probability to the seismic intensity corresponding to the MCE level ground motions. It was critically compared with the acceptable CMR (i.e. the CMR computed with reference to a seismic intensity corresponding to the 10% collapse probability instead of MCE level ground motions). Frame with shear reinforcement in beam-column joints has achieved CMR 11% higher than the acceptable thus passing the criterion. However, the deficient frame achieved CMR 29% less than the conforming frame. This confirms the efficacy of beam-column joint detailing in reducing collapse risk.

scholarly journals AN INVESTIGATION OF THE EFFECTIVENESS OF THE FRAMING SYSTEMS IN STEEL STRUCTURES SUBJECTED TO BLAST LOADING

2014 ◽  
Vol 20 (6) ◽  
pp. 767-777 ◽  
Author(s):  
Amy Coffield ◽  
Hojjat Adeli
Keyword(s):  
Failure Modes ◽  
Plastic Hinge ◽  
Blast Loading ◽  
Steel Structures ◽  
Response Analysis ◽  
Plastic Hinges ◽  
Braced Frame ◽  
Concentrically Braced Frame ◽  
Moment Resisting ◽  
Applied Element Method

The effectiveness of different framing systems for three seismically designed steel frame structures subjected to blast loading is investigated. The three faming systems considered are: a moment resisting frame (MRF), a concentrically braced frame (CBF) and an eccentrically braced frame (EBF). The blast loads are assumed to be unconfined, free air burst detonated 15 ft (4.572 m) from one of the center columns. The structures are modeled and analyzed using the Applied Element Method, which allows the structure to be evaluated during and through failure. Failure modes are investigated through a plastic hinge analysis and member failure comparison. Also, a global response analysis is observed through comparison of roof deflections and accelerations. A conclusion of this research is that braced frames provide a higher level of resistance to the blast loading scenario investigated in this research. Both the CBF and EBF had a smaller number of failed members and plastic hinges compared to the MRF. They also had smaller roof deflection and acceleration. The CBF yielded the fewest number of plastic hinges but the EBF had a slightly fewer number of failed members.

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