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Civil-Comp Proceedings
ISSN 1759-3433
CCP: 83
Edited by: B.H.V. Topping, G. Montero and R. Montenegro
Paper 253

Reinforced Concrete Wide-Beams vs. Deep-Beams: A Comparison of their Behaviour under Seismic Loads, Employing Pushover Analysis

J. Lavado, M. Moll and R. Lopez

School of Civil Engineers, University of Granada, Spain

Full Bibliographic Reference for this paper
J. Lavado, M. Moll, R. Lopez, "Reinforced Concrete Wide-Beams vs. Deep-Beams: A Comparison of their Behaviour under Seismic Loads, Employing Pushover Analysis", in B.H.V. Topping, G. Montero, R. Montenegro, (Editors), "Proceedings of the Eighth International Conference on Computational Structures Technology", Civil-Comp Press, Stirlingshire, UK, Paper 253, 2006. doi:10.4203/ccp.83.253
Keywords: pushover analysis, nonlinear static analysis, wide-beams, deep-beams, capacity spectrum method, seismic analysis.

In this paper a static nonlinear analysis (pushover analysis) [1,2] is performed, with the aim to compare the behaviour of frames designed with wide-beams and deep-beams, under the Spanish Norm NCSE-02 specifications [3]. Several aspects of the seismic behaviour (energy dissipation capacity of the structure, lateral displacements for verification of serviceability limit states) are analyzed in both solutions, and the results compared.

Two-dimensional moment resisting interior frames (three-storey and six-storey) have been analyzed. These structures are typical Spanish residential buildings, which are cast in-situ.

The main conclusions of this study are:

  1. In three-storey frames, the behaviour with wide-beams is generally better than with deep-beams. The frames with deep-beams fail in a soft-storey mechanism way, in the columns of the first floor. In the wide-beam frame the hinges are mostly formed in the beams, with an overall ductility equal to 1.77 at the performance point, which almost corresponds to the behaviour factor considered in the design process of the frame (q=2).
  2. In six-storey frames the three frames analyzed reach the performance point first before other limits. The behaviour is similar in frames with wide-beams and with deep-beams: in frames with deep-beams the total number of hinges is higher (with about 25% more hinges) than in frames with wide-beams, but the number of hinges in beams are very similar in the three cases. At the performance point there are no differences in terms of overall ductility, with values of around 65-70% of the behaviour factor considered in the design process of the frames (q=2 for wide-beams and q=3 for deep-beams).
  3. Comparing three-floor frames and six-floor frames a better behaviour is observed in those frames without considering the 4 minimum flexure reinforcement ratio for beams. The tendency is to form more hinges in beams and less hinges in columns in these frames. The modification of this minimum ratio should be a claim to the Spanish Commission of the Seismic Norm.
  4. In locations with basic ground acceleration ab = 0.16g, the behaviour of wide-beams frames and deep-beams frames is similar enough, as is demonstrated in this paper, mostly because of the ductility requirements in the steel reinforcement with ab >= 0.16g. Nevertheless, in locations with ab < 0.16g (where these specifications are not prescribed), the behaviour of the wide-beam frames must be analyzed in furthermore investigation. In taller buildings (more than six floors) the behaviour of wide-beams frames must also be considered.

"ATC-40: Seismic Evaluation and Retrofit of Concrete Buildings", Applied Technology Council, Redwood City, CA, 1996.
Kim S., D'Amore E., "Pushover analysis procedure in earthquake engineering", Earthquake Spectra, 15(3), 417-434, 1999. doi:10.1193/1.1586051
NCSE-02 (Norma de Construcción Sismorresistente de Estructuras), Ministerio de Fomento, 2002.

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