An Experimental Study on the Displacement Capacities of Reinforced Concrete Beams

In the analysis of a building, besides the classical assumptions, the variables that depend on the behavior of reinforced concrete and are considered to be less important are ignored, and the calculations are tried to be facilitated. In order to determine the accuracy and validity of the assumptions and simplifications and/or to realistically determine the mechanical behavior of reinforced concrete under various stresses, both analytical and experimental intensive studies are carried out, and depending on the developments - especially all over the world - in recent years, serious changes have been made in the earthquake resistant building design regulations.

The methods used to investigate and determine the behavior of structures under dynamic loads can be grouped under three main headings. These are field investigations, mathematical models and laboratory tests after earthquakes. Laboratory tests can also be evaluated under three main headings, these are shaking table tests, quasi-static tests and dynamic tests.

This research project has two main objectives. The first of these is to write algorithms that can determine the load-displacement relationship of reinforced concrete beams and to experimentally verify these algorithms in the building mechanics laboratory. The second aim is to discuss the accuracy and reality of various assumptions made in the design regulations in the context of beam behavior both in the design of new structures and in the evaluation of existing structures.

In the proposed project, 2 reinforced concrete beams will be designed and manufactured, each meeting the new construction regulations and reflecting the material quality and design deficiencies of the existing structures.

The experimental load-displacement relations of the samples will be determined with the help of a static and semi-dynamic loading mechanism in the Civil Engineering Laboratory of Istanbul Aydın University with displacement control. The analytical load-displacement algorithm will be updated with the experimental data to be obtained and the rupture/fracture limits will be reflected in the mathematical models.

Three researchers and 5 technicians of the Civil Engineering laboratory will contribute to the realization of the project, which is planned to last for 12 months. In the first six months of the project, the design and manufacture of the test samples and the control of the test equipment will be carried out. In this period, it is planned to make the experimental system fully usable and to complete the analytical model software. In the second six-month period, the completion of the experiments and the verification of the analytical algorithm based on the experimental results will be carried out. In this period, the design code assumptions, especially the displacement capacities of reinforced concrete beams, will be examined in comparison with analytical and experimental results.

Project Results:

As can be seen from the comparison made on the basis of the limited test sample result, it can be said that there may be cases where the confined concrete unit shortening limit value in the Turkish Earthquake Code is insufficient to describe the failure limit (limit of reduction in bearing strength). It can be said that such situations will be encountered frequently in the performance evaluation process of existing structures, especially in beams where the lateral reinforcement spacing is insufficient in terms of regulation conditions, since the concrete controlled forward damage limits are observed according to the confined concrete unit shortening. It can be said that the damage limit (Istanbul Aydın University Approach) determined with the help of the equation (1) gives good results in general.

güncelleme: 11.2.2022 10:58