PROCEEDINGS OF THE EIGHTH INTERNATIONAL CONFERENCE ON COMPUTATIONAL STRUCTURES TECHNOLOGY
Edited by: B.H.V. Topping, G. Montero and R. Montenegro
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
pushover analysis, nonlinear static analysis, wide-beams, deep-beams, capacity spectrum method, seismic analysis.
In this paper a static nonlinear analysis (pushover analysis) [1
] 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:
- 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).
- 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).
- 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.
- 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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