Paslanmaya maruz kalmış betonarme kolonlarda donatı sıyrılma hesabı için deneye dayalı bir modelin geliştirilmesi

Reinforcement corrosion has an important place in construction industry due to its problems. Corrosion does not only affect country economy, but also adversely affects structural safety. Corrosion in structures might also causes to premature repairing, strengthening or demolishing of structures before completing their life cycle. Corrosion in reinforcement bars causes different effective as cracking, spalling of concrete, reductions in cross-section area of reinforcement bar, and reductions in bond strength between concrete and reinforcement bars. In recent years, there are different models and approaches have been developed to assess the seismic performance of reinforced concrete buildings. However, in such assessments, the effect of corrosion on a structure has been considered only reduction in cross sectional area of reinforcement bar. Reduction in the bond strength between concrete and reinforcement bars due to corrosion has been ignored and thus additional lateral displacement due to slippage of reinforcement bars has not been considered in such assessment methods. The most important concept which describes the relationship between concrete and reinforcement bar is bond strength and slippage of reinforcement bars that depending on this. This relationship gains more importance due to corrosion. In the available literature, there is no any empirical model to predict slippage of reinforcement bars in reinforced concrete columns as a function of corrosion. Therefore, an approach that does not fully reflect the reality is used for the evaluation of reinforced concrete structures subjected to corrosion by taking into account only the reduction in reinforcement area. In performed experimental studies; even for the uncorroded reinforced concrete columns, slippage of reinforcement bars contributed 24% to 40% of total lateral displacement where it is inevitable to have more ratios for corroded columns that highly affects the structural performance. In this study, firstly; reinforcement bars of full scaled reinforced concrete columns were corroded by using accelerated corrosion method. Within the scope of the study, reinforcement bars were corroded as controlled and the effects of the corrosion at different corrosion levels were evaluated experimentally. Since corrosion increases the bond strength up to a certain value of corrosion level and then decreases the bond strength, for the current study used accelerated corrosion method within controlled has an important place. Corrosion has shown different behavior at lower and higher concrete strength levels. To consider this effect, three different concrete classes were used as lower and upper boundaries during experimental study. Firstly, reinforced concrete columns were divided into three main groups for three different concrete classes (C8, C20 and C30); then each main group were divided into four subgroups for different theoretical corrosion levels of 2%, 4%, 6%, and %10. Two groups were identified during the test of the lateral loading for the applied axial load according to the load carrying capacities of the reinforced columns as 20% and 40%. By considering these three parameters crosswise, a total of 30 reinforced concrete columns were tested. By applying a reversed cycling load program for the reinforced concrete columns; loaddisplacement, moment-curvature, reinforcement bond-slip values of reinforced concrete columns subjected to corrosion were obtained experimentally. An empirical model was developed to predict the slippage of reinforcement bars as a function of different corrosion levels and concrete strength levels from obtained experimental tests results. According to the performed of this study, where it has not been performed previously in the literature, a new window will be opened in the assessment of seismic performance levels of corroded reinforced concrete structures. In addition, empirical models have been developed to predict the yield strength, ultimate strength, ductility ratios, energy absorption capacity depending on the corrosion level of corroded reinforced concrete columns. In addition to all these models; to be used in nondestructive assessment methods; a new model has been developed to predict the corrosion level in reinforced concrete reinforcement, energy absorption capacities and seismic performance levels of corroded reinforced concrete columns as a function of initial corrosion crack widths.