Aleksandr Sokolov

Experimental Investigation of Tension Stiffening in RC Ties

The increasing application of high-performance materials in civil engineering led to the development of reinforced concrete (RC) structures with reduced cross sections and increased spans. In such structures serviceability limit state often becomes the governing condition of the design. Present study investigates the deformation behaviour of high-strength RC ties reinforced with high-grade bars. Experimental investigation was carried out measuring the postcracking stiffness of the specimens at high strain levels. It was found that, despite the reduction in stiffness, a considerable part of the average tensile stresses were carried by the concrete at the advanced loading stages, thus effectively stiffening the RC member.

Experimental Investigation of the Capacity of Steel Fibers to Ensure the Structural Integrity of Reinforced Concrete Specimens Coated with CFRP Sheets

The capacity of steel fibers to ensure the structural integrity of reinforced concrete specimens coated with CFRP sheets was investigated. Test data for four ties and eight beams reinforced with steel or glass-FRP bars are presented. Experiments showed that the fibers significantly increased the cracking resistance and altered the failure character from the splitting of concrete to the debonding of the external sheets, which noticeably increased the load-carrying capacity of the strengthened specimens.

Steel Fibres: Effective Way to Prevent Failure of the Concrete Bonded with FRP Sheets

Although the efficiency of steel fibres for improving mechanical properties (cracking resistance and failure toughness) of the concrete has been broadly discussed in the literature, the number of studies dedicated to the fibre effect on structural behaviour of the externally bonded elements is limited. This experimental study investigates the influence of steel fibres on the failure character of concrete elements strengthened with external carbon fibre reinforced polymer sheets. The elements were subjected to different loading conditions. The test data of four ties and eight beams are presented. Different materials were used for the internal bar reinforcement: in addition to the conventional steel, high-grade steel and glass fibre reinforced polymer bars were also considered. The experimental results indicated that the fibres, by significantly increasing the cracking resistance, alter the failure character from splitting of the concrete to the bond loss of the external sheets and thus noticeably increase the load bearing capacity of the elements.

Experimental Investigation of the Deformation Behavior of SFRC Beams with an Ordinary Reinforcement

The paper reports test results for steel-fiber-reinforced concrete beams. Four-point bending tests on 12 full-scale beams (with longitudinal reinforcement ratios of 0.3 and 0.6%) were carried out to investigate the postcracking behavior of the members. The content of fibers, spaced at equal intervals, ranged from 0 to 120 kg/m3, resulting in the amount of 0, 0.5, 1.0, and 1.5% by volume. A simple deflection analysis technique based on a linear interpolation between the cracking and yielding points is discussed. It is shown that this technique adequately assesses the bending moment at yielding, but significantly overestimates the corresponding deflections. It is concluded that the model discussed should be improved by taking into account the tension stiffening effect.