Summary


The assessment of deformation capacity in reinforced concrete members is very important to ensure an adequate structural behaviour when subject to a combination of gravitational and lateral loads. Current European regulations (Eurocode 8, 2004) have adopted certain analytical and empirical methods in order to assess the deformation capacity of reinforced concrete members. These methods have been developed on the basis of a large database of experimental tests with geometric and mechanical characteristics that cover a wide range of parameters. Nevertheless, there is still scarcity or lack of experimental testing for certain types of members, such as columns with a shear slenderness higher than 6, and High Strength Concrete columns (fc higher than 50 MPa). On the other hand, some studies have shown that the results obtained vary to a great extent depending on whether the analytical methods or the empirical methods proposed in the same code (Eurocode 8) are adopted.

Therefore, in this thesis a study on the deformation capacity of Normal Strength and High Strength Concrete slender columns has been carried out with the following purposes: (1) identifying the parameters with the strongest influence on deformation capacity; (2) checking whether the current methods can be applied to slender reinforced concrete columns, and, in case they cannot, (3) proposing general methods whose application to this type of members is feasible. 

This study on the deformation capacity of concrete members has been carried out based on an experimental series of 44 tests on reinforced concrete members subject to constant axial load and monotonic bending. Additionally, a series of 250 numerical simulations has been developed, under the same structural and load conditions, by using the non-linear analysis program “ATENA-2D”.

Building on the results obtained experimentally and numerically, a study of the parameters that have the strongest influence on the deformational behaviour of reinforced concrete members has been carried out. Finally, this has made it possible to develop a proposal of simplified methods for the assessment of the deformation capacity of reinforced concrete members, for the elastic and ultimate state.  

These methods have been developed both for the verifying and for the cross-section design of reinforced concrete members. Based on the methods, it is posible to assess in a very straightforward manner the following variables: effective elastic and ultímate stiffness, effective elastic and ultimate displacement, and, consequently, the displacement ductility factor.

The proposed methods are valid in members having characteristics within the following ranges: axial load between 0.1 and 0.6, shear slenderness between 3.5 and 10.5, concrete strength between 30 MPa and 90 MPa, longitudinal reinforcement ratio between 1% and 4% and confinement volumetric geometric reinforcement ratio between 1% and 4%.