Title:
Earthquake-Resistant Design of Reinforced Concrete Structures: Shortcomings of Current Methods
Author(s):
Michael D. Kotsovos, Angeliki Baka, and Emanuel Vougioukas
Publication:
Structural Journal
Volume:
100
Issue:
1
Appears on pages(s):
11-18
Keywords:
concrete; design; reinforced concrete; seismic; test.
DOI:
10.14359/12434
Date:
1/1/2003
Abstract:
The work forms part of an attempt to investigate the causes of unexpected damage suffered by vertical structural elements of reinforced concrete (RC) structures during the July 9, 1999, Athens earthquake. It is based on an experimental investigation of the behavior of simply supported two-span linear elements designed from first principles by using methods based on two contrasting concepts: the truss analogy (as applied by the design methods incorporated in current codes of practice) and the compressive-force path concept. These elements were tested under both monotonic and cyclic transverse loading combined with a constant axial-compressive concentric force. The results of the tests indicated that not only does the truss analogy not safeguard against a brittle type of failure in the region of the point of inflection, but it may, in fact, cause such a failure in regions heavily reinforced with stirrups widely referred to as critical lengths. In contrast with the truss analogy, the compressive-force path method was found to yield design solutions that fulfil the code requirements for strength and ductility for the case of monotonic loading. For the case of cyclic loading, however, the longitudinal extension of criss-crossing inclined cracking within noncritical regions was found to destroy the bond between concrete and steel, thus leading to premature reduction of the strength and energy-absorption capacities of all the structural elements tested. It appears, therefore, that an efficient earthquake-resistant design method must also safeguard against failure associated with bond destruction.