Mikrobölgelemenin bir tanımı; olası deprem özellikleri ile mevcut zemin özellikleri arasındaki karşılıklı etkileşimi göz önüne alarak, zemin yüzeyinde seçilen deprem özelliklerini ve bunlarla ilişkili yapı tasarım parametrelerinin değişimini belirlemek olarak verilebilir. Bu çalışmada, mikrobölgeleme amaçlı zemin davranış analizlerinde yapay ve ölçeklenmiş gerçek kayıtlar kullanılarak farklı deprem ve yapı tasarımı parametrelerinin zemin yüzeyindeki değişimi incelenmiştir. Çalışmanın ilk aşamasında, gerçek deprem kayıtları kullanılarak en büyük ivme ölçekleme yöntemi ve RASCAL yapay kayıt programı yardımıyla iki farklı şekilde ivme zaman kayıtları üretilmiştir. Balıkesir tasarım depremi için üretilen bu kayıtlar, 105 zemin profilinin davranış analizlerinde kullanılmış ve yüzeydeki yer hareketi parametrelerinin frekans dağılımları hesaplanmıştır. En büyük yatay ivme, Arias şiddeti ve spektral ivme olarak seçilen parametrelere ait frekans dağılımlarında, kullanılan gerçek kayıtların önemli bir faktör olduğu görülmüştür. Sonuçlar özellikle en büyük ivme ölçekleme yöntemi için kullanılan gerçek kayıtlara dayalı olarak frekans dağılımlarının önemli oranda değişebileceğini göstermiştir. Diğer taraftan bu etki tasarım parametresine göre de farklılık gösterebilmektedir. Çalışmanın ikinci aşamasında RASCAL programı ile üretilen kayıtların kullanıldığı davranış analizleri için, NEHRP kriterlerinin sağlandığı bir optimizasyon yaklaşımına dayalı olarak spektral ivmeler belirlenmiş ve bu ivmeler aynı tehlike seviyesi için NEHRP yaklaşık yöntemine göre bulunan spektral ivmelerle karşılaştırılmıştır. Sonuçlar tasarım depremi ve zemin özellikleri arasındaki karşılıklı etkileşime dayalı farklılıkların D grubu zeminler için daha yüksek olduğunu ve bu etkileşimde yüzeydeki yer hareketi özelliklerinin zemin davranış analizleri ile bulunmasının önemli olduğunu göstermektedir. Anahtar Kelimeler: Mikrobölgeleme, yapay deprem kayıtları, ölçekleme, en büyük ivme, Arias şiddeti, spektral ivme.Soil layers under earthquake excitations can strongly influence earthquake characteristics on the ground surface. These effects may be evaluated with respect to structural design parameters based on microzonation studies. In a microzonation study, the variation of selected ground motion parameters on the ground surface are determined by taking into account the interaction between ground motion and local soil conditions. In this study, the interaction between earthquake and soil characteristics were evaluated based on simulated and real acceleration records used for site response analyses with respect to different parameters. In the first stage, simulated acceleration records were generated by RASCAL frequency domain procedure (Silva and Lee, 1987) and real acceleration records were scaled with respect to the estimated peak ground acceleration. RASCAL (Response Spectra and Acceleration Scaling) is a semi-empirical procedure, which evolved from random vibration theory-based techniques, with the additional utilization of the observed Fourier phase spectrum of a real ground motion recording. Input target spectra used in this simulation procedure are uniform hazard spectra developed using two attenuation relationships based on different data sets for predetermined probabilistic earthquake hazard (M=7.5 with epicenter of R=40km corresponding to exceedance probability of 10% in 50 years) (Ansal, 2001). Input acceleration time histories were selected from the earthquake records in Turkey with magnitude range, M≥5 and distance, 27km<R<71km. Taking into account regional source characteristics for Balıkesir, stress drop was taken as Δσ=100 bar. For the whole-path attenuation, frequency-dependent Q model of Q(f)=300 f 0.5 was adopted. As for the near surface attenuation, the kappa values was taken as κ=0.035. With RASCAL program, six simulated time histories were generated based on six different real earthquake records. In the scaling option, previously recorded real acceleration records were scaled with respect to the peak ground acceleration estimated based on the earthquake design parameters (M=7.5, R=40 km). The peak ground acceleration on the rock outcrop was calculated as 0.26g, corresponding to the exceedance probability of 10% in 50 years. Previously recorded real acceleration records were selected with respect to ratio factor determined for scaling procedure. With scaling option, six acceleration time histories were calculated based on different earthquake records. Characteristics of both sets of acceleration records were calculated and compared. It was observed that the range of some parameters such as maximum velocity and velocity spectrum intensity were smaller for the records calculated by RASCAL procedure. Using two groups of acceleration records, site response analyses were conducted by SHAKE91 (Idriss and Sun, 1992) based on 1D equivalent linear method for 105 soil profiles selected previously. Response variability on the ground surface was evaluated in terms of histograms of peak acceleration, Arias intensity and spectral acceleration at 0.2s. In the case of peak and spectral accelerations at 0.2s, the analyses using real scaled records yielded very different statistical distributions for each record. However, the results of the analyses using input records generated by RASCAL gave very similar statistical distributions for all the records in this set. In the case of Arias intensity, both sets of records were found to be more effective yielding different statistical distributions on the ground surface for each input record. In the second stage of this study, the average acceleration response spectra for each soil profile were calculated according to the analyses conducted with records simulated by RASCAL. Utilizing an optimization approach that provide all the requirements of the NEHRP design spectrum, spectral accelerations for short and long periods were determined for average response spectra. These spectral accelerations were compared with spectral accelerations obtained from the NEHRP formulation corresponding to the same earthquake hazard level. The results indicate that the variability based on the interaction between earthquake and soil characteristics was relatively large for D group soils and that the frequency content of ground motions have significant effect on site response. Keywords: Microzonation, simulated acceleration records, scaling, peak ground acceleration, Arias intensity, spectral accelerations. 
