Analysis of the factors affecting the adhesion of the sickle profile reinforcement with concrete
Abstract
The effect of concrete strength on the tension of reinforcement of sickle-shaped profile for its removal from concrete is analyzed. It is shown that these stresses depend linearly on the concrete compressive strength and on the relative anchorage length, which is equal to the ratio of the anchorage length to the core diameter. It was found that the coefficient of adhesion of the bars to the concrete, which relates the relative length of the anchoring with the ratio of the stresses of the rod when pulled to the prism strength of concrete, is 0.83. It is determined that, under all other conditions, the tension of the rods of the annular profile in comparison with the sickle profile is 1.4 times higher for the excision.
The technique of determination of maximum coupling stresses of cores of a periodic profile, developed in NIIZhB, is analyzed. It is found that the boundary stresses of the clutch, calculated by this method, are significantly lower than those obtained experimentally. The hypothesis is formulated that this technique does not take into account the possible participation in the work to pull out the core of a larger volume of concrete adjacent to the contact layer.
It is shown that in the Eurocode 2 formula it is expedient to take into account the Rem index, which characterizes the relative cross-sectional area of deflection, and the impact of which can be estimated only after extensive experimental studies are used to determine the maximum coupling stresses of concrete rod reinforcement.
In the future, it is necessary to carry out experimental and theoretical studies of anchoring rods of sickle-shaped profile in concrete, reinforced with fiber reinforcement of Ukrainian mass production at the expense of its 55 - 140 kg per 1 m3 of concrete mixture, which takes place in real load-bearing structures, as foreign researchers note that for dispersive reinforcement costs up to 70 kg / m3, it has less impact on the adhesion of the bars to the concrete than the compressive strength of the concrete.
