Effect of stirrup spacing and reinforcement class on structural dynamic behavior in reinforced concrete columns

Architects and engineers design the structures according to the conditions specified in the regulations and determine the design life. The occurrence of unexpected situations such as overloading the structure (flood, earthquake, explosion, etc.), repetitive application of loads or the renewal of regulations as a result of developing technologies lead to question the reliability of the design life of the structures designed according to the old regulations. Unfortunately, the researches show that the seismic fragility of the columns in the poorly designed and detailed reinforced concrete buildings in the earthquakes that occurred, and the seismic fragility of the reinforced concrete columns designed according to the old regulations were seriously damaged and even collapsed. In order to prevent such undesirable situations, the behavior of reinforced concrete columns under earthquakes should be determined. In this thesis, natural vibration frequencies and damping rates were determined and compared by performing experiments on reinforced concrete column samples with different reinforcement classes and stirrup spacing, which will represent the structures designed according to the old and current regulations, on a shaking table to simulate the earthquake situation in the laboratory environment. As a result of the data obtained, it was determined that the natural vibration frequencies of the columns were affected by approximately 6-7% of the stirrup spacing and 25% of the reinforcement class; It was determined that the damping rate of the columns was affected by the stirrup spacing between 4.98-9.6% and the reinforcement class between 36-39%. Experimental studies will create a significant database on the earthquake performance of columns with sparse stirrup spacing and low reinforcement class, which are frequently encountered in the reinforced concrete building stock in our country, and will contribute significantly to the development of analytical methods used in determining the earthquake performance of these structures.