Ali Haydar Kayhan

In this study, the solution model based on the stochastic harmony search algorithm was proposed to obtain real ground motion (GM) records for nonlinear dynamic analysis of structures. Obtaining the GM record problem was formulated as a constrained engineering optimization problem. The solution model ensures spectral compatibility between the mean horizontal spectrum of selected ground motion (GM) records and the target horizontal spectrum, as well as the mean vertical spectrum of the selected GMs with the target vertical spectrum. This model also allows the management of record-to-record variability in both horizontal and vertical components of the selected GMs. Moreover, the model effectively addresses the period-dependent record-to-record variability in all orientations of seismic excitations simultaneously using a single-scale value, preserving the relative amplitude and phasing of actual GM components. The efficiency of the model has been demonstrated through numerical examples with various uniform hazard spectra, specifically those based on Eurocode-8 and the Turkish Building Earthquake Code, as well as scenario-based target spectra. The results demonstrate that through using the proposed model it is possible to obtain GM records with the desired spectral compatibility and spectral dispersion for both horizontal and vertical GM components. Thus, the model can be used as an efficient way to obtain appropriate GM records for nonlinear dynamic analyses of both two- and three-dimensional structural models for performance-based designs and/or evaluation frameworks, considering seismic excitations in both horizontal and vertical directions.

Wide beam structures are categorized as Limited Ductility Class in Turkey and elsewhere and considered not fit for construction in areas of high seismicity. One of the main reasons that wide beam structures are considered to possess limited ductility is the perceived low local ductility of the wide beams, due to the high reinforcement ratios. Wide beams have small depths, which indeed require higher reinforcement ratios to produce the necessary moment capacities, as compared to normal beams. However, the low local ductility of the wide beams can be contested. This paper presents a database of more than 150 beam sections, some of which are normal and some of which are wide beams. The moment-rotation relationships were computed for all the sections, and the sectional ductility was calculated from the yield and ultimate rotations. The relations between sectional ductility and other parameters such as section aspect ratio, longitudinal reinforcement ratio and transverse reinforcement ratio were investigated. An example of the relation between ductility and section properties, in this case section aspect ratio is shown. Both positive and negative ductility were calculated and plotted. It should be noted that beams with section ratio of 0.5 are conventional beams, while the rest are wide beams. The values of ductility vary for all beams, and conventional beams have a slightly wider spread. While these parameters vary within the section database, the sectional ductility oscillates around 30, and no clear correlations could be established for any of the above-mentioned parameters. There were no significant differences between the average sectional ductility of conventional and wide beams. For this dataset, the mean positive ductility was 29.66 and 29.33 for conventional and wide beams respectively, and the mean negative ductility was 28.96 and 31.50 for conventional and wide beams, respectively.