Flessione e Taglio in Lastre Rettangolari in C.A. con Appoggi Indiretti su due Lati Opposti

Simply-supported one-way R/C slabs are commonly used in the roofs of underground facilities and in temporary structures, where the rather limited predominantly-permanent service loads are accompanied in certain cases by large variable loads (like those induced by heavy-duty vehicles). Because of slabs simple geometry, straightforward restraints and moderate spans, however, the structural requirements are often underrated, to the detriment of the reinforcement, that may be either too heavy or too light. To have fresh information on two typical bar arrangements in rectangular R/C slabs suspended along their short sides via corbels (dapped ends), four R/C slabs have been recently tested in Milan in bending and shear (size: 130 x 220 x 15 cm; simply-supported span: 210 cm; corbel span and depth: 10 x 10 cm; transversely-distributed or con¬centrated load acting at mid-span or at 1/10 of the span; displacement-controlled tests). In the two slabs Type A, the reinforcement consists (a) in a set of longitudinal hooked bars placed inside the corbels and anchored in thick part of the slab, and (b) in a bottom net whose longitudinal bars are bent-up and hooked at their extremities (acting like ties). In the two slabs Type B, the reinforcement consists of two similar nets, the first with the longitudinal bars running between the end-faces of the corbels and the second placed close to the intrados of the thick part (in both slabs the anchored extremities of the longitudinal bars are straight). The experimental results are satisfactorily matched by simple strut-and-tie systems (Slabs Type A) and by the equation provided in EC2 (Slabs Type B), and demonstrate – once more – that refining bar layout can markedly improve slab behavior, at little or no extra cost.