Long‐term data of reinforced concrete beams subjected to high sustained loads and simplified prediction method

Abstract

In 1967–1985, a research campaign comprising a unique set of long‐term experimental data on concrete beams was conducted in joint collaboration with four Belgian research institutes to determine the influence of creep and shrinkage on the long‐term behavior of reinforced concrete members. The main aim of the research campaign was the determination of the long‐term behavior of cracking and deformations subjected to permanent loads considering the influence of the magnitude of the loads and various reinforcement ratios.The objective of this article is twofold: to provide an overview of the measured data of the reinforced beams of the research campaign, which has never been published before, and to propose a simplified calculation method based on available models in literature that can predict the available measurement data. A simplified calculation model is proposed, which accounts for nonlinear creep strains due to high stresses, shrinkage, aging, and cracking in reinforced concrete beams. This numerical method is based on a cross‐sectional analysis formulated using the layered Euler‐Bernoulli beam theory, allowing fast and accurate predictions of strains, stresses, and deflections as a function of time based on fib Model Code 2010 and EN1992‐1‐1. The measurements of the beams subjected to high permanent loads during a time period of 4 years are compared to the results evaluated with the proposed simplified calculation model. The results show that the proposed simplified calculation method based on the current models of EN1992‐1‐1 and fib Model Code 2010 can predict the long‐term behavior of reinforced concrete beams subjected to high loads in good agreement with the measurements.