In this study, the seismic behavior of regular and irregular composite moment resisting frame (CMRF) buildings was investigated. To this aim, 5, 8, 10, 13 and 15-story CMRFs having concrete filled steel tube columns and composite beams were designed at high ductility level and their performances were evaluated comparatively. The case study CMRF structures were categorized into two groups as regular and irregular in elevation. Examined irregular structures have setbacks in different story levels. During the design and performance analysis, SeismoStruct software was employed. Nonlinear static pushover and incremental dynamic analyses were used in the seismic performance assessment. The uniform and triangular load distributions were considered in the pushover analysis while a total of 22 earthquake acceleration records were utilized in the dynamic analysis. The variation in the lateral response, global yielding value, interstory drift, behavior factor, inherent strength factor, overstrength factor, and ductility factor were examined for the regular and irregular CMRF structures. It was observed that the regular CMRFs were more consistent with the design assumptions as compared to the irregular ones. Moreover, the former exhibited more uniform non-elastic demands over the building height according to the results of the incremental dynamic analysis. Under the seismic scenario adopted, all the building types yielded higher values of the behavior factor complied with the limits available in the code.

In the studies carried out until today, rubber-modified self-compacting concretes (RMSCC) had been manufactured by replacing the aggregates of the waste vehicle tires (WVT) in the grain size distribution and particles that have different workability, different mechanical, and physical properties. However, variation of the carrying capacity of the RMSCC elements produced with different slenderness ratio h/b ratio under axial load had not been researched in previous studies. Within the scope of this study, the change in physical and mechanical properties of RMSCC elements produced by using different h/b ratios had been examined both experimentally and theoretically. Since the natural sand and WVT aggregate used in the production of concrete and their grain sizes are in the same range, WVT aggregate has been replaced by natural sand in 4 different proportions. These ratios were used as 5%, 10%, 15% and 20% of the natural sand volume, respectively. Slenderness ratios, h/b ratios were 1.0, 1.5, 2.0, 2.5, 3.0 and 3.5, and experimental and theoretical investigations had been performed for 90 samples in total. The linear regression models of the obtained results had been analyzed and the equations with the h/b ratios according to these models had been produced. The results of the obtained equations and the results of experimental axial pressure had been compared. In addition to the amount of WVT aggregate used and the increase in the ratio of h/b, the compressive strength losses had caused by different rates on the samples. The effect of the WVT aggregate ratio on the compressive strength had become more significant with the increase in use rate. Besides, regression analyzes had been performed to determine the effect of h/b ratio on the compressive strength. In conclusion, regression R2 (coefficient of determination) values that belong to equations obtained had been found over 0.95.

In this study, the seismic behavior of steel-concrete composite buildings designed using ÇYTHYE 2016 and TBDY 2018 was investigated. For this purpose, composite moment resisting frame buildings with concrete filled steel tube columns and composite beams with 5, 10, 15 and 20 stories are modeled. Buildings are designed at high ductility (DCH) levels. During the design of the DCH class structures, the design was carried out for the ZA soil class for 0.79 g PGA in the region selected from the earthquake map given in the regulations. Within the scope of the study, SeismoStruct software was used during the design and performance evaluation of the structures. Incremental dynamic analyzes were used along with nonlinear static pushover analyses. In the static pushover analysis, uniform and triangular load distributions of the lateral load are adopted. In the dynamic analysis, 16 earthquake ground motions were obtained from AFAD earthquake acceleration databases according to the relevant design area and used. The variation of the seismic behavior of CMRFs depending on the variation of the floor number was investigated using nonlinear analysis results. Accordingly, the variation in lateral response, overstrength factors and ductility factors for CMRF structures are presented comparatively. In addition, the section deformation capacities were investigated during the IDR changes during dynamic and static nonlinear analyses. The behavior factor of all CMRFs, especially the CMRFs studied in the case study, demonstrated above-expected performance according to the design assumptions.