Analysis of fatigue crack growth in reinforced concrete beams

Mechanical behavior of reinforced concrete members is influenced by the action of unknown crack bridging reactions of rebars. Under cyclic loading, due to progressive growth of cracks, this bridging action contributes to the overall strength, stiffness and hysteretic behavior of the member. In this work, fatigue behavior of reinforced concrete beams are studied using a crack propagation law, developed using dimensional analysis for plain concrete with the effect of reinforcement being simulated through constraint exerted on the crack opening. The parameters considered in the model are fracture toughness, crack length, loading ratio and structural size. A numerical procedure is followed to compute fatigue life of RC beams and the dissipated energy in the steel reinforcement due to the shake down phenomenon under cyclic loading. Through a sensitivity study, it is concluded that the structural size is the most sensitive parameter in the fatigue crack propagation phenomenon. Furthermore, the residual moment carrying capacity of an RC member is determined as a function of crack extension by including the bond-slip mechanism.

Kaiser effect observation in reinforced concrete structures and its use for damage assessment

Reinforced concrete (RC) beams of span 3 m were tested under incremental cyclic load at different loading rates and simultaneously during the fracture process in the RC beams acoustic emissions (AE) were recorded. An attempt has been made to study the Kaiser effect as a measure of damage in RC beams. It was observed that RC beams made with high strength concrete under incremental cyclic loading showed an obvious Kaiser effect before the failure load. The results may be useful to study the damage in concrete structures and provide a reference for the application of Kaiser effect in engineering practice. (C) 2014 Politechnika Wroclawska. Published by Elsevier Urban & Partner Sp. z.o.o. All rights reserved.

Formulas, tables, and graphs for trapezoidal reinforced concrete beams

Not available.

The patents in the introduction of reinforced concrete in Spain: "Alhondiga de Bilbao" case study

Reinforced concrete structures are introduced in Spain mainly by French influence. This happens in the late nineteenth century, following the scheme operating through proprietary systems prevailing in Europe. Systems initially have poor scientific support reaching, even early twentieth century, an impediment to the development of concrete structures, due to the lack of knowledge shown, as well as due to a series of accidents. Therefore, from the end of the first decade of the past century are enacted a series of regulations in many countries, that will change the design and calculation of reinforced concrete structure. The knowledge of the environment of the patent systems, its beginnings and the circumstances of their application allow us to understand the constraints of the early concrete structures, as presented in the Bilbao wine store (1906).