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Abstract

Dynamic Behavior of Bridge Pier with Elastomeric Bearings under Earthquake Effects for Different Soil layers and Support Conditions An isolated bridge pier having elastomeric bearings is modeled by finite element technique and dynamic responses under the effect of earthquake accelerations which are obtained by linear solution methods in time and frequency domain and the results are evaluated by probabilistic distributions. For this purpose, stationary accelerations characterized by Kanai-Tajimi power spectrum are simulated for different soil types and twenty nonstationary records in each soil group are obtained by modulating the amplitudes in harmony with 1992 Erzincan earthquake NS component. The pier responses and deck displacements are obtained in time domain for different support and soil conditions by using simulated horizontal and vertical accelerations. Furthermore, variances of the responses are obtained in frequency domain by assuming stationary stochastic behavior and by using power density and cross-power spectra of the applied simultaneous motions. The results are evaluated by those of the time domain solutions and peak responses and variations of peak response factors are determined. For dynamic peak responses, the response quantities corresponding to exceedance probabilities of 2%, 10% and 50% (median) are predicted depending upon soil types by use of Rayleigh distribution model

Keywords

• Peak responses, rubber, Kanai-Tajimi, nonstationary, stochastic

Deprem Etkisindeki Elastomer Mesnetli Köprü Ayağının Farklı Zemin ve Mesnet Koşullarında Dinamik Davranışı

Abstract

Elastomer mesnetli bir köprü ayağı sonlu elemanlar yöntemi ile modellenerek deprem ivmeleri etkisindeki dinamik davranışı, doğrusal elastik çözümleme ile zaman ve frekans tanım alanındaki (stokastik) yöntemlerle belirlenmekte ve sonuçları olasılık dağılımları ile irdelenmektedir. Bu amaçla durağan ivmeler, zeminleri karakterize eden Kanai-Tajimi güç spektrumu kullanılarak türetilmekte ve daha sonra genlikler, 1992 Erzincan depremi KG bileşeninin genlik değişimi ile uyumlu zarf fonksiyonları aracılığıyla değiştirilerek her zemin türünde yirmişer adet durağandışı ivme kayıtları elde edilmektedir. Türetilen yatay ve düşey ivme bileşenleri, köprü ayağına uygulanarak ayaktaki kesit zorları ile tabliyedeki yatay yerdeğiştirmeler, üst yapının farklı mesnetlenmesi ve değişik zemin koşulları için zaman tanım alanında elde edilmektedir. Ayrıca, frekans tanım alanında durağan stokastik davranış kabulü ile sisteme aynı anda etkiyen ivmelere ait güç yoğunluk ve çapraz güç spektrumları kullanılarak sisteme ait kesit zorlarının varyansları elde edilmektedir. Sonuçlar zaman tanım alanı çözümleri ile değerlendirilerek maksimum tepkiler ve maksimum davranış faktörlerinin değişimleri belirlenmektedir. Dinamik davranıştaki maksimum tepkiler, Rayleigh dağılımları ile ele alınarak %2, %10 ve %50 (ortalama) aşılma olasılıklarına karşı gelen davranışlar zemin tiplerine bağlı olarak tahmin edilmektedir

Keywords

• Maksimum davranış, elastomer, Kanai-Tajimi, durağandışı, stokastik

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