Longitudinal reinforcement ratio in lightweight aggregate concrete beams: Fid-Bau Portal

Longitudinal reinforcement ratio in lightweight aggregate concrete beams

Dias-da-Costa, D. / Carmo, R.N.F. / Graça-e-Costa, R. / Valença, J. / Alfaiate, J.

Highlights • Numerical study focusing the serviceability of LWAC beams under flexural loading. • Extensive validation of a discrete crack model with image processing techniques. • The procedure in CEB design manual provides satisfactory estimates for LWAC beams. • In aggressive environments the reinforcement ratio should be between 1% and 2%. • Crack widths calculated using Eurocode 2 might be underestimated in LWAC beams.

Abstract The development of lightweight aggregate concrete (LWAC) has brought new design opportunities. The high strength and simultaneous low densities can lead to economically competitive structural solutions, which has immediate impact on seismic construction and on the strengthening of existing structures. Currently, most studies are focused on the mechanical properties and the structural behaviour under ultimate limit states, lacking experimental and numerical data concerning the serviceability of LWAC members. In this scope, a parametric study was undertaken to address the serviceability LWAC beams under flexural loading for a complete range of longitudinal reinforcement ratios. An advanced finite element technology was validated in the simulation of the overall and localised response of the members, the latter including crack openings and patterns. It was observed that the tensile reinforcement ratio should be kept bellow 2% when the durability of the LWAC is important. Nevertheless, reinforcement ratios bellow 1% might not fulfil the design requirements for aggressive environments. The numerical findings also point out that the characteristic crack openings evaluated according to the Eurocode 2 might underestimate the actual value for LWAC beams.