Seismic performance of ductile and nominally ductile reinforced concrete moment resisting frames. I. Experimental study

1998 ◽  
Vol 25 (2) ◽  
pp. 331-341 ◽  
Author(s):  
André Filiatrault ◽  
Éric Lachapelle ◽  
Patrick Lamontagne
Keyword(s):  
Reinforced Concrete ◽  
Time History ◽  
Experimental Results ◽  
Shake Table ◽  
Concrete Frames ◽  
Seismic Behaviour ◽  
Shake Table Tests ◽  
Moment Resisting Frames ◽  
Moment Resisting ◽  
Design Earthquake

This paper is the first of two companion papers on the evaluation of the level of protection offered by ductile and nominally ductile reinforced concrete structures in Canada. In this paper, the seismic behaviour of two half-scale reinforced concrete moment resisting frames is investigated by shake table tests. In the second paper, the experimental results obtained from the shake table tests are compared with the results generated from inelastic time-history dynamic analyses. Each frame had two bays and two storeys with overall dimensions of 5 m in width and 3 m in height. The first structure was designed as a ductile frame according to current Canadian standards; and the second structure incorporated only nominally ductile details. Two levels of intensity were retained for the historical ground motion used in the tests. The first level was representative of the design earthquake considered; the amplitudes were doubled for the second intensity. The ductile structure performed well during both tests. The frame with nominal ductility performed well during the first test, but was on the verge of collapse after the second test. Based on these experimental results, recommendations are presented to harmonize the seismic protection of ductile and nominally ductile reinforced concrete frames in Canada.Key words: moment resisting frames, earthquakes, reinforced concrete, seismic, shake table.

Seismic performance of ductile and nominally ductile reinforced concrete moment resisting frames. II. Analytical study

1998 ◽  
Vol 25 (2) ◽  
pp. 342-352 ◽  
Author(s):  
André Filiatrault ◽  
Éric Lachapelle ◽  
Patrick Lamontagne
Keyword(s):  
Reinforced Concrete ◽  
Dynamic Analysis ◽  
Dynamic Modelling ◽  
Time History ◽  
Reduction Factor ◽  
Major Influence ◽  
Shake Table ◽  
Analysis Model ◽  
Moment Resisting Frames ◽  
Moment Resisting

This paper is the second of two companion papers on the evaluation of the level of protection offered by ductile and nominally ductile reinforced concrete structures. In the first paper, experimental results obtained from shake table tests of two half-scale reinforced concrete moment resisting frames were reported. The first structure was designed as a ductile frame (force reduction factor R = 4) according to current Canadian standards; and the second structure incorporated only nominally ductile details (R = 2). This second paper deals with the dynamic modelling of the two structures. A simple nonlinear time-history dynamic analysis model is presented and its predictions are compared with the shake table test results. It is shown that inelastic deformations in beam-column joints have a major influence on the seismic response of the structures. Approximate modelling of these joint deformations, based on equivalent rotational springs, can provide a good correlation between numerical and experimental results.Key words: dynamic analysis, moment resisting frames, earthquakes, reinforced concrete, seismic.

SHAKING TABLE TESTS ON HAUNCH RETROFITTED REINFORCED CONCRETE FRAMES

2019 ◽  
Vol 3 (Special Issue on First SACEE'19) ◽  
pp. 233-240
Author(s):  
Junaid Akbar ◽  
Naveed Ahmad ◽  
Bashir Alam
Keyword(s):  
Reinforced Concrete ◽  
Shaking Table ◽  
Shaking Table Tests ◽  
Concrete Frames ◽  
Seismic Behaviour ◽  
Response Modification Factor ◽  
Rc Frames ◽  
Moment Resisting ◽  
Modification Factor ◽  
Rare Earthquake

Shaking table tests were performed on five one-third reduced scale two storey reinforced concrete (RC) moment resisting frames having construction defects (using low strength concrete without confining ties in beam-column joints, larger tie spacing, and reduced longitudinal and transverse reinforcements). The deficient frames were observed to have severe joint damageability, resulting in joint panel cover spalling and core concrete crushing. Haunch retrofitting technique was adopted to upgrade the seismic behaviour of deficient RC frames. Additional four deficient RC frames were built and retrofitted with steel haunch; both axially stiffer and deformable with energy dissipation, fixed to the beam-column connections to reduce shear demand on joint panels. The as-built and retrofitted frame seismic response modification factor (R) was calculated and compared to evaluate the viability of the haunch retrofitting technique. The haunch retrofitting technique increased the lateral stiffness and strength of the structure, resulting in the increase of structure overstrength. The retrofitting increased R factor by sixty percent to one hundred percent. The presented results indicate that the technique can significantly enhance the seismic performance of deficient RC frames, particularly against the frequent and rare earthquake events.

A static force-based procedure for the seismic assessment of existing reinforced concrete moment resisting frames

1997 ◽  
Vol 30 (3) ◽  
pp. 213-226 ◽  
Author(s):  
R. Park
Keyword(s):  
Reinforced Concrete ◽  
Experimental Testing ◽  
Response Spectra ◽  
Seismic Assessment ◽  
Reinforced Concrete Beams ◽  
Assessment Procedure ◽  
Seismic Behaviour ◽  
Moment Resisting Frames ◽  
Ductility Factor ◽  
Moment Resisting

A force-based seismic assessment procedure for existing reinforced concrete moment resisting frames is discussed. The assessment procedure is based on determining the probable strength and ductility of the critical mechanism of post-elastic deformation of the frame. Account is taken of the likely seismic behaviour of reinforced concrete beams, columns and beam-column joints with substandard reinforcement details typical of structures designed before the 1970s, as determined by the results of experimental testing and analytical studies. The assessment aims at determining the available lateral load strength and structural (displacement) ductility factor of the frames so that the designer can determine the likely seismic performance of the structure by referring to acceleration response spectra for design earthquake forces for various levels of structural ductility factor.

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 Seismic Upgrading of Steel Moment-Resisting Frames by Means of Friction Devices

2014 ◽  
Vol 8 (1) ◽  
pp. 289-299 ◽  
Author(s):  
Esra Mete Güneyisi ◽  
Mario D'Aniello ◽  
Raffaele Landolfo
Keyword(s):  
Structural Response ◽  
Time History ◽  
Seismic Behaviour ◽  
Steel Moment Resisting Frames ◽  
Residual Drift ◽  
Moment Resisting Frames ◽  
Drift Ratio ◽  
Nonlinear Time History Analyses ◽  
Moment Resisting ◽  
Nonlinear Time History

In recent decades, several passive energy dissipation systems have been conceived in order to minimize the damage in structural and non-structural components of either new or existing buildings. In this study, the use of friction damped tension-compression diagonal braces for seismic upgrading of a steel moment resisting frames is investigated. To this aim, nonlinear time history analyses have been carried out on a set of representative frames with and without friction damped braces. In the nonlinear time history analyses, two sets of natural accelerograms compatible with seismic hazard levels of 10% and 2% probability of exceedance in 50 years have been considered. Under these records, the structural response has been comparatively investigated in terms of the maximum inter-storey drift ratio, maximum storey acceleration, residual drift ratio and displacement demand for the friction device. The results clearly highlighted that the application of friction damped braces allows reducing the damages to the main structural elements, thus significantly improving the seismic behaviour of the frame.

DUCTILITY FACTOR OF REINFORCED CONCRETE FRAME WITH WEAK BEAM-COLUMN JOINT

2021 ◽  
Author(s):  
Inayat Ullah ◽  
Muhammad Ejaz Ahmad ◽  
Naveed Ahmad ◽  
Saima Pervez ◽  
Syed Qaisar Abbas
Keyword(s):  
Reinforced Concrete ◽  
Time History ◽  
Test Model ◽  
Shake Table ◽  
Northridge Earthquake ◽  
Shear Reinforcement ◽  
Reinforced Concrete Frame ◽  
Ground Acceleration ◽  
Shake Table Tests ◽  
Ductility Factor

Code requirements are usually fulfilled during the design of a building. On the other hand, reinforced concrete (RC) frames (particularly in the developing regions of the world) are found deficient due to unregulated constructions. Majority of such deficient structures lack shear reinforcement in beam-column joints. Collapse of these deficient buildings (as a result of limited ductility) triggered many socio-economic and human losses which is evident from recent earthquake disasters. This paper presents an experimental study which was conducted on a 1:4 reduced scale three-storey RC special moment resisting frame (SMRF) lacking shear reinforcement in the beam-column joints. The lack of confinement bars causes shear hinging of joints that reduces the displacement ductility of the frame. Shake-table tests were conducted on test model that was subjected to acceleration time history of 1994 Northridge earthquake, having a peak ground acceleration of 0.57g. The acceleration was linearly scaled to multiple levels and to sinusoidal base excitations of various frequencies and displacements. Moderate to severe damage at each storey level was observed in the joint panels due to the lack of lateral reinforcing ties in the joints. The data obtained from shake table tests were processed and analysed to develop a lateral force-deformation capacity curve, which was bi-linearized as an elasto-plastic curve to compute various response parameters of frame. The ductility factor (Rμ) of the tested model was found to be equal to 1.95, which is thirty-five percent less than the code recommended value of Rμ for RC SMRF structures.

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