Resumen

ARCHUNDIA ARANDA, Hans I.  y  TENA COLUNGA, Arturo. Sección crítica, esbeltez y regiones B-D para diseño a cortante de trabes de concreto reforzado. Concr. cem. investig. desarro [online]. 2015, vol.7, n.1, pp.2-29. ISSN 2007-3011.

The shear critical section was suggested by the "Committee 326" (1962 a/b) as a parameter that controls the shear design of slender reinforced concrete (RC) beams. Although the shear critical section is supported by tests in beams without stirrups, it is also applied in beams with transverse reinforcement. Actually, the slenderness in beams with and without stirrups is sized by means of the a/d ratio; nevertheless, this parameter is only full valid in beams without transverse reinforcement (Kani 1964). Schlaich et al., (1987) classified RC elements into B and D regions. These B-D regions are identified with elastic stress fields, but are designed with plastic truss models or beam theory equations that work with plastic concrete and steel yielding. All these extrapolations confuse the shear design in RC beams. In this paper rational definitions are presented for the shear critical section, beam slenderness, and B-D regions. These definitions are supported with stress fields and truss models and cover uncracked and diagonal cracked stages. Some experimental tests were studied with these new definitions validating the original ACI-318 Code shear design approach for slender beams. The results of the described studies allowed identifying a structural anomaly that was named pseudo-slenderness. This structural anomaly can be prevented attending simple detailing recommendations for the transverse reinforcement.

Palabras llave : shear; critical section; beam slenderness; B-D regions; stress fields; truss models; strut and tie models.

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