Effect of Elastomeric Bearings in Bridge Piers

Abstract

In this paper, the influence of elastomeric bearings is investigated in terms of seismic responses and presented under effects of severe ground motions. For this purpose, seismic performance of an isolated pier system is analytically studied by using time history analyses. The isolation system is assembled by elastomeric bearings composed of rubber layers and steel-shims. The bearings are located between pier-top ends and box-girder of the bridge deck. Seismic solutions are obtained for isolated system and non-isolated pier system known as rigid connection. Time-dependent response quantities are obtained in transverse direction for two strong quakes. Additionally, nonlinear static procedure is carried out to obtain lateral seismic capacity. Thus, the displacement and shear force capacity are determined for the considered pier systems. Seismic responses are comparatively presented in terms of superstructure and base response values. Thanks to the isolation system, the bearings have yielded lower peak displacements and base responses with seismic demand as well. On the other hand, higher seismic capacity has been obtained in case of isolation system and the results are presented by computed lateral capacity curves. The results show that the elastomeric bearing is an effective tool in lateral strength and modal behavior of the pier system as well.

Keywords

• elastomer
• seismic
• time history
• capacity
• bridge-pier

Köprü ayaklarinda elastomer mesnetlerin etkisi

Öz

Bu çalışmada, elastomerik mesnetlerin etkisi sismik davranışlar açısından şiddetli yer hareketleri altında incelenmektedir. Bu amaçla, izolasyonlu bir ayak sisteminin sismik performansı, zaman tanım alanı analizleri kullanılarak analitik olarak incelenmiştir. İzolasyon sistemi, kauçuk katmanlardan ve çelik simlerden oluşan elastomerik mesnetlerden oluşmaktadır. İzolatörler, ayak üst uçları ile köprü tabliyeinin kutu kirişi arasında bulunmaktadır. Rijit bağlantılı olarak bilinen sabit birleşimli sistem ve izolasyonlu ayak sistemi için sismik çözümler elde edilmiştir. Kaydedilmiş İki güçlü deprem için enine doğrultuda zamana bağlı davranış büyüklükleri elde edilmektedir. Ayrıca, yatay kapasiteyi elde etmek için doğrusal olmayan statik prosedürler uygulanmıştır. Böylece, dikkate alınan ayak sistemleri için yer değiştirme ve kesme kuvveti kapasitesi belirlenmiştir. Sismik davranışlar, tabliye ve ayak tepki değerleri açısından karşılaştırmalı olarak sunulmuştur. İzolasyon sistemi, sismik talep ile daha düşük tepe yer değiştirmeleri ve taban tepkilerinin elde edilmesini sağlamıştır. Ayrıca, izolasyon sistemi kullanılması durumunda daha yüksek sismik kapasite elde edilmiş ve hesaplanan yanal kapasite eğrileri çalışmada sunulmuştur. Elde edilen sonuçlar, elastomerik mesnetin ayak sisteminin yatay mukavemetinde ve modal davranışında da etkili bir araç olduğunu göstermektedir.

Anahtar Kelimeler

• kauçuk
• sismik
• zaman tanım alanı
• kapasite
• köprü ayağı

Kaynakça

1. [1] Sheikh, M.N., Vivier, A., Legeron, F. Seismic vulnerability of hollow core concrete bridge pier. In Proceedings of the 5th International Conference on Concrete under Severe Conditions of Environment and Loading, Consec ’07, Paris, France, , pp. 1445–1454, 2007.
2. [2] Broderick, B.M., Elnashai, A.S. Analysis of the failure of interstate 10 freeway ramp during the Northridge earthquake of 17 January 1994. Earthquake Engineering and Structural Dynamics. 1995, 24, pp.189–208.
3. [3] Elnashai, A.S., Bommer, J.J., Baron, C.I., Lee, D.H., Salama, A.I. Selected engineering seismology and structural engineering studies of the Hyogo-Ken Nanbu (Great Hanshin) earthquake of 17 January 1995. ESEE research report: No. 95-2. London: Imperial College, 1995.
4. [4] Abdelkareem, K.H., Machida, A. Effect of vertical motion of earthquake on failure mode and ductility of RC bridge piers. 12th World Conference on Earthquake Engineering, Auckland, New Zeland, 2000.
5. [5] Priestly, M.J.N., Calvi, G.M. Strategies for repair and seismic upgrading of Bolu viaduct 1, Turkey, Journal of Earthquake Engineering, 2002, 06, pp.157-184.
6. [6] Farshad H. D., & Alam, M.S. Effect of different steel-reinforced elastomeric isolators on the seismic fragility of a highway bridge, Structural Control and Health Monitoring. 2016, 24, pp. 1-15. DOI: 10.1002/stc.1866
7. [7] Sarıtaş, F., Hasgür, Z. Dynamic behavior of an isolated bridge pier under earthquake effects for different soil layers and support conditions, Digest 2014, December 2014, pp. 1733-1756.
8. [8] Sarıtaş, F. Performance-based seismic assessment of a base-isolated bridge-pier. European Journal of Environmental and Civil Engineering, 2019 . DOI:https://doi.org/10.1080/19648189.2019.1647463

9. [9] Kunde, M.C., Jangid, R.S. Seismic behavior of isolated bridges: A-State-of-the-art review. Electronic Journal of Structural Engineering, 2003, 3, pp. 140-170.
10. [10] Razzaq, M.K., Bhuiyan, A.R. Okui, Y., Mitamura, H., Imai, T. Effect of rubber bearings modeling on seismic response of base isolated highway bridge. Joint Conference Proceedings, 7th International Conference on Urban Earthquake Engineering (7CUEE) & 5th International Conference on Earthquake Engineering (5ICEE), 2010, Tokyo, Japan.
11. [11] AASHTO. LFRD Bridge design specifications. American association of state highway and transportation officials: loading and general information. Washington D.C., 2012.
12. [12] DIN4141-14. Structural bearings, laminated elastomeric bearings design and construction. Deutsche Institut für Normung. Berlin, 1985.
13. [13] Naeim, F., Kelly, J.M. Design of seismic isolated structure. USA, John Wiley & Sons, 1999.
14. [14] CSI, Computer & Structures Inc. Linear and nonlinear static and dynamic analysis of three-dimensional structures. Berkeley, California, 2019.