Evaluation of crack width in reinforced concrete beams subjected to variable load

Abstract

In this paper, the influence of loading histories of variable (imposed) actions on the behavior of reinforced concrete beams and especially the crack width was analyzed. For the evaluation of long-term effects (effects due to creep and shrinkage in concrete structures), quasi-permanent combination of actions was used to verify the reversible limit state. An experimental program and analytical research was performed to compare the experimentally obtained results of crack width and results of proposed calculation models given in EN 1992-1-1 Eurocode 2 and in the fib Model code 2010. For two specific loading histories, of series of beams D and E, the quasi-permanent coefficient ψ2 was defined using the quasi-permanent combination of actions. These loading histories were consisting of long-term permanent action G and repeated variable action Q. The variable load was applied in cycles of loading/unloading for 24 and 48 hours in the period of 330 days. A total of eight reinforced concrete beams, dimensions 15/28/300 cm were tested.