Análise de sensibilidade entre modelos de cálculo de resistência à força cortante de lajes alveolares pré-fabricadas protendidas

Abstract

Regarding the constant increase in systems using precast members, specially prestressed hollow-core slabs, due to cost and schedule reduction, it was necessary to review past researches related to the shear capacity of hollow-core slabs. This dissertation aimed to compare the theoretical shear strength, provisioned by the building codes ACI 318-2014, BS EN 1992-1-1:2004 e ABNT NBR 14861:2011 with the experimental results found in the literature and to determinate how much the most sensitive variables affect the shear strength, through a sensitivity analysis . 144 slabs were studied, with the depth (H) ranging from 151 mm to 500 mm. The comparisons showed that the equation 6.2a from BS EN 1992-1-1:2004 was the most conservative, with the application of reduction factors, presenting values of the ratio between the experimental failure load and theoretical capacity, also known as ξ, ranging from 0,59 to 3,76. Equation 6.4, however, presented non conservative and unsatisfactory results, even with the reduction factors applied, despite having the least variation and the average ξ being the closest to the realistic model. The results from the sensitivity analysis with reference to the shear strength influential parameters indicate that the greatest effect comes from Σbw and the effective depth (d), being the geometry of the hollow-core elements the most important factor to be considered in structure design. We also concluded that the safest and simultaneously most conservative model is the ACI 318-2014, with the lowest probability of occurring ξ<1, of value 2,89%.