The shear resistance of a member without shear reinforcement according to Eurocode 2; the error of the calculated value and the mechanical explanation of the problem

In this paper the shear resistance of a member without shear reinforcement according to Eurocode 2 is investigated. This expression, as most expressions of design codes typically used to estimate the nominal shear resistance, has been created based on experimental investigations. It will be verified that in case of non-prestressed reinforced concrete member without stirrups, the shear resistance is carried by the shear resistance of the compressive zone; and the shear resistance given by the empirical expression of Eurocode 2 is actually the shear resistance of the compressive zone.Knowing the mechanical background of the empirical expressions of Eurocode 2, the limits of its applicability can be shown, thus its error can be predicted. Using the reports of experimental investigations, it is easy to find cases to prove the correctness of the error-prediction. In this paper simple modifications will be suggested to Eurocode 2 shear design procedures, by which a more consistent level of safety can be ensured.

Shrinkage and temperature reinforcement in concrete liquid-containing structures.

Cracking due to shrinkage is a widespread problem in large concrete members such as walls and slabs. When shrinkage strains are restrained, tensile stresses develop in concrete. Concrete cracks when tensile stresses exceed the tensile strength of concrete. In general, concrete standards and codes of practice recommend a minimum area of reinforcement for shrinkage and temperature effects. In some cases, large structural elements provide significant restraint to a concrete member that the specified minimum area of reinforcement needs to be increased. This research studies the response of reinforced concrete walls to shrinkage strains. In this study, nonlinear finite element analysis is applied to simulate the cracking behaviour of concrete and predict crack pattern and tensile stresses in reinforcement in the vicinity of cracks. This research is looking for the effective shrinkage and temperature reinforcement in liquid-containing structures where cracking of concrete is of major concern.

Analytical modeling of the contact pressure at the steel-concrete interface

This research studies the effect of corrosion on bond strength at the steel-concrete interface in a reinforced concrete member. Bond stress, which can be defined as the shear stress which develops along the lateral surface of the bar, is expressed as a function of contact pressure at the steel-concrete interface. An analytical model of bond which describes the contact pressure between the reinforcing bar and concrete in a reinforced concrete member is developed. The expression for the reduction in contact pressure due to the accumulation of corrosion products is then developed using the model developed for the uncorroded reinforcing steel bar. The developed analytical model was implemented in a finite element analysis, which was conducted using ABAQUS, of pull-out specimens conducted by Amleh (2000). A reasonable good agreement between the experimental and finite element analysis results was obtained.

Shrinkage and temperature reinforcement in concrete liquid-containing structures.

Cracking due to shrinkage is a widespread problem in large concrete members such as walls and slabs. When shrinkage strains are restrained, tensile stresses develop in concrete. Concrete cracks when tensile stresses exceed the tensile strength of concrete. In general, concrete standards and codes of practice recommend a minimum area of reinforcement for shrinkage and temperature effects. In some cases, large structural elements provide significant restraint to a concrete member that the specified minimum area of reinforcement needs to be increased. This research studies the response of reinforced concrete walls to shrinkage strains. In this study, nonlinear finite element analysis is applied to simulate the cracking behaviour of concrete and predict crack pattern and tensile stresses in reinforcement in the vicinity of cracks. This research is looking for the effective shrinkage and temperature reinforcement in liquid-containing structures where cracking of concrete is of major concern.

Analytical modeling of the contact pressure at the steel-concrete interface

This research studies the effect of corrosion on bond strength at the steel-concrete interface in a reinforced concrete member. Bond stress, which can be defined as the shear stress which develops along the lateral surface of the bar, is expressed as a function of contact pressure at the steel-concrete interface. An analytical model of bond which describes the contact pressure between the reinforcing bar and concrete in a reinforced concrete member is developed. The expression for the reduction in contact pressure due to the accumulation of corrosion products is then developed using the model developed for the uncorroded reinforcing steel bar. The developed analytical model was implemented in a finite element analysis, which was conducted using ABAQUS, of pull-out specimens conducted by Amleh (2000). A reasonable good agreement between the experimental and finite element analysis results was obtained.