Deprem Etkisindeki Elastomer Mesnetli Köprü Ayağının Farklı Zemin ve Mesnet Koşullarında Dinamik Davranışı
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
Anahtar Kelimeler:
Maksimum davranış, elastomer, Kanai-Tajimi, durağandışı, stokastik
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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,
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- Mahmoud, S., Austrell, P. E., Jankowski, R., Simulation of the Response of Base- Isolated Buildings under Earthquake Excitations Considering Soil Flexibility, Earthquake Engineering & Engineering Vibration, 11(3), 359-374, 2012.
- Dicleli, M., Karalar, M., Optimum Characteristic Properties of Isolators with Bilinear Force–Displacement Hysteresis for Seismic Protection of Bridges Built on Various Site Soils,Soil Dynamics and Earthquake Engineering 31, 982–995, 2011.
- Ala Saadeghvaziri, M., Foutch, D. A., Dynamic Behavior of RC Highway Bridges under the Combined Effect of Vertical and Horizontal Earthquake Motions, Earthquake Engineering and Structural Dynamics, 20(6), 535-549, 1991.
- Ala Saadeghvaziri, M., Foutch, D. A., Foutch, Behavior of RC Columns under Non- proportionally Varying Axial Load, Journal of Structural Engineering, 116(7), 1835- 1856, 1990.
- Pagnini, L. C., Solari, G., Stochastic Analysis of the Linear Equivalent Response of Bridge Piers with Aseismic Devices, Earthquake Engineering and Structural Dynamics, 28, 543-560, 1999.
- Jangid, R. S., Equivalent Linear Stochastic Seismic Response of Isolated Bridges,Journal of Sound and Vibration, 309, 805-822, 2008.
- Kunde, M. C., Jangid, R. S., Effects of Pier and Deck Flexibility on the Seismic Response of Isolated Bridges, Journal of Bridge Engineering, 11(1), 109-121, 2006.
- Gongkang, F., Elastically Supported Cantilever Beam Subjected to Nonstationary Seismic Excitation, Earthquake Engineering and Structural Dynamics, 27, 977-995, 1998.
- Hasgür, Z., Stochastic Analysis of Bridge Piers with Symmetric Cantilevers under the Base Accelerations, Bulletin of the Istanbul Technical University, 48(3-4) 657-667,
- Ates, S., Bayraktar, A., Dumaoglu, A. A., The Effect of Spatially Varying Earthquake Ground Motions on the Stochastic Response of Bridges Isolated with Friction Pendulum Systems, Soil Dynamics and Earthquake Engineering, 26, 31-44, 2006.
- Sungur, I., Stochastic Response to Earthquake Forces of a Cable-Stayed Bridge, Engineering Structure, 15(5), 307-314, 1993.
- Allam, Said M. Datta, T. K., Response Spectrum Analysis of Suspension Bridges for Random Ground Motion, Journal of Bridge Engineering, 7(6), 325-337, 2002.
- Zhang, Z. C., Lin, J. H., Zhang, Y. H., Zhaoa, Y., Howsonc, W. P., Williams, F. W., Non-Stationary Random Vibration Analysis for Train–Bridge Systems Subjected to Horizontal Earthquakes, Engineering Structures 32, 3571–3582, 2010.
- Vanmarcke, E. H., Lomnitz, C., Rosenbleuth, E., Structural Response to Earthquakes, Chapter 8 in Seismic Risk and Engineering Decisions, Elsevier, New York, 1976.
- Davenport, A. G., Note on the Distribution of Largest Values of Random Function with Application to Gust Loading, Proc. Inst. of Civil Eng., 28, 187–196, 1964.
- Mylonakis, G., Syngros, C., Gazetas, G., Tazoh, T., The Role of Soil in the Collapse of Piers of Hanshin Expressway in the Kobe Earthquake, Earthquake Engineering and Structural Dynamics, 35, 547-575, 2006.
- Jangid, R. S., Equivalent Linear Stochastic Seismic Response of Isolated Bridges, Journal of Sound and Vibration, 309, 805-822, 2006.
- Clough R. W., Penzien, J., Dynamics of Structures, Mc-Graw Hill Book Company, Second Edition, New York, 1993.
- Der Kiureghian, A., Neuenhofer, A., A Response Spectrum Method for Multiple- Support Seismic Excitations, UCB/EERC-91/08, University of California, Berkeley, 1991.
- Jennings, P.C., Housner, G. W., Tsai, N. C., Simulated Earthquake Motions for Design Purposes, Proc. 4th World Conf. Earthquake Engineering, 1(a-1), 145–160, Chile, 1969.
- Sarıtaş, F., Kutu Kirişli Köprülerin Stokastik Dinamik Analizi, Doktora Tezi, İstanbul Teknik Üniversitesi, 2008.
- Naeim, F., Kelly, J. M., Design of Seismic Isolated Structures, John Wiley & Sons, Inc., U.S.A., 1999.
- AASHTO, AASHTO LFRD Bridge Design Specifications, American Association of State Highway and Transportation Officials, Joints and Bearings, Washington D.C, 2007.
- DIN 4141-14, Structural Bearings, Laminated Elastomeric Bearings Design and Construction, Deutsche Institut für Normung, 1985.
- SAP2000, Structural Analysis Program, Computers and Structures Inc., Berkeley,
- ISSN: 1300-3453
- Yayın Aralığı: Yılda 6 Sayı
- Yayıncı: TMMOB İnşaat Mühendisleri Odası