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.

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.

scholarly journals An Investigation of the Fundamental Period of Vibration for Moment Resisting Concrete Frames

2019 ◽  
Vol 5 (12) ◽  
pp. 2626-2642
Author(s):  
Ahmed Nader Mohamed ◽  
Khaled F. El Kashif ◽  
Hamed M. Salem
Keyword(s):  
Dynamic Analysis ◽  
Nonlinear Dynamic Analysis ◽  
Reduction Factor ◽  
Fundamental Period ◽  
Base Shear ◽  
Empirical Formulas ◽  
Moment Resisting Frames ◽  
Element Size ◽  
Moment Resisting ◽  
Earthquake Design

The determination of fundamental period of vibration for structures is essential to earthquake design. The current codes provide empirical formulas to estimate the approximated fundamental period and these formulas are dependent on building material, height of structure or number of stories. Such a formulation is excessively conservative and unable to account for other parameters such as: length to width ratios, vertical element size and floors area. This study investigated the fundamental periods of mid-rise reinforced concrete moment resisting frames. A total of 13 moment resisting frames were analyzed by ETABS 15.2.2, for gross and cracked eigenvalue analysis and Extreme Loading for Structures Software® or ELS, for non-linear dynamic analysis. The estimated periods of vibration were compared with empirical equations, including current code equations. As expected, the results show that building periods estimated based on simple equations provided by earthquake design codes in Europe (EC8) and America (UBC97 and ASCE 7-10) are significantly smaller than the periods computed using nonlinear dynamic analysis. Based on the results obtained from the analyzed models, equations for calculating period of vibration are proposed. These proposed equations will allow design engineers to quickly and accurately estimate the fundamental period of moment resisting frames with taking different length to width ratios, vertical element size, floors area and building height into account. The interaction between reduction factor and the reduced period of vibration is studied, and it is found that values of maximum period of vibration can be used as an alternative method to calculate the inelastic base shear value without taking reduction factors in consideration.

scholarly journals Experimental Study on Seismic Retrofitting of Reinforced Concrete Frames Using Welded Concrete-Filled Steel Tubes

2020 ◽  
Vol 10 (20) ◽  
pp. 7061 ◽  
Author(s):  
Kyong Min Ro ◽  
Min Sook Kim ◽  
Young Hak Lee
Keyword(s):  
Reinforced Concrete ◽  
Seismic Performance ◽  
Seismic Energy ◽  
Maximum Load ◽  
Steel Tube ◽  
Seismic Retrofitting ◽  
Reinforced Concrete Frame ◽  
Concrete Frame ◽  
Moment Resisting Frames ◽  
Moment Resisting

Buildings constructed with non-seismic details are at risk of damage and collapse when an earthquake occurs due to a lack of strength, stiffness, and ductility. For reinforced concrete (RC) moment-resisting frames, seismic retrofitting methods that can enhance strength or ductility should be applied. However, such strategies have many disadvantages related to constructability, serviceability, securing integrity, and cost. In this paper, a welded concrete-filled steel tube (WCFST) system was examined in order to resolve the problems of the existing seismic retrofitting methods for RC moment-resisting frames. To evaluate the seismic performance of the proposed system, two specimens, one with non-seismic details and another reinforced with a WCFST seismic system, were manufactured for the cyclic loading tests. As a result of the experiments, the specimen retrofitted with the WCFST system showed maximum load, effective stiffness, and energy dissipation capacity values approximately 3, 2, and 2.5 times greater, respectively, than those obtained from the existing reinforced concrete frame specimen. The experimental results indicate that the proposed WCFST system is expected to be effective at improving the seismic performance by enhancing both the strength of the existing reinforced concrete frame structures and the dissipation of the seismic energy.

scholarly journals Shake Table Response of Unreinforced Masonry and Reinforced Concrete Elements of Special Moment Resisting Frame

2019 ◽  
Vol 2019 ◽  
pp. 1-17 ◽  
Author(s):  
Syed Azmat Ali Shah ◽  
Junaid Shah Khan ◽  
Syed Muhammad Ali ◽  
Khan Shahzada ◽  
Waqar Ahmad ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Seismic Performance ◽  
Masonry Wall ◽  
Masonry Walls ◽  
Shake Table ◽  
Base Excitation ◽  
Reinforced Concrete Frame ◽  
Infill Walls ◽  
Concrete Frame ◽  
Moment Resisting

Half-scaled reinforced concrete frame of two storeys and two bays with unreinforced masonry (URM) infill walls was subjected to base excitation on a shake table for seismic performance evaluation. Considering the high seismic hazard Zone IV of Pakistan, reinforcement detailing in the RC frame is provided according to special moment resisting frames (SMFRs) requirement of Building Code of Pakistan Seismic-Provisions (BCP SP-2007). The reinforced concrete frame was infilled with in-plane solid masonry walls in its interior frame, in-plane masonry walls with door and window openings in the exterior frame, out-of-plane solid masonry wall, and masonry wall with door and window openings in its interior frame. For seismic capacity qualification test, the structure was subjected to three runs of unidirectional base excitation with increasing intensity. For system identification, ambient-free vibration tests were performed at different stages of experiment. Seismic performance of brick masonry infill walls in reinforced concrete frame structures was evaluated. During the shake table test, performance of URM infill walls was satisfactory until design ground acceleration was 0.40g with a global drift of 0.23%. The test was continued till 1.24g of base acceleration. This paper presents key findings from the shake table tests, including the qualitative damage observations and quantitative force-displacement, and hysteretic response of the test specimen at different levels of excitation. Experimental results of this test will serve as a benchmark for validation of numerical and analytical models.

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