Seismic Fragility Assessment of Continuous Integral Bridge Frames with Variable Expansion Joint Clearances

Authors: P. Mounnarath, U. Schmitz, Ch. Zhang

Abstract:

Fragility analysis is an effective tool for the seismic vulnerability assessment of civil structures in the last several years. The design of the expansion joints according to various bridge design codes is almost inconsistent, and only a few studies have focused on this problem so far. In this study, the influence of the expansion joint clearances between the girder ends and the abutment backwalls on the seismic fragility assessment of continuous integral bridge frames is investigated. The gaps (ranging from 60 mm, 150 mm, 250 mm and 350 mm) are designed by following two different bridge design code specifications, namely, Caltrans and Eurocode 8-2. Five bridge models are analyzed and compared. The first bridge model serves as a reference. This model uses three-dimensional reinforced concrete fiber beam-column elements with simplified supports at both ends of the girder. The other four models also employ reinforced concrete fiber beam-column elements but include the abutment backfill stiffness and four different gap values. The nonlinear time history analysis is performed. The artificial ground motion sets, which have the peak ground accelerations (PGAs) ranging from 0.1 g to 1.0 g with an increment of 0.05 g, are taken as input. The soil-structure interaction and the P-Δ effects are also included in the analysis. The component fragility curves in terms of the curvature ductility demand to the capacity ratio of the piers and the displacement demand to the capacity ratio of the abutment sliding bearings are established and compared. The system fragility curves are then obtained by combining the component fragility curves. Our results show that in the component fragility analysis, the reference bridge model exhibits a severe vulnerability compared to that of other sophisticated bridge models for all damage states. In the system fragility analysis, the reference curves illustrate a smaller damage probability in the earlier PGA ranges for the first three damage states, they then show a higher fragility compared to other curves in the larger PGA levels. In the fourth damage state, the reference curve has the smallest vulnerability. In both the component and the system fragility analysis, the same trend is found that the bridge models with smaller clearances exhibit a smaller fragility compared to that with larger openings. However, the bridge model with a maximum clearance still induces a minimum pounding force effect.

Keywords: Expansion joint clearance, fiber beam-column element, fragility assessment, time history analysis.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1111681

References:

[1] Caltrans, Seismic Design Criteria Version 1.7. California Department of Transportation, CA: Sacramento, 2013.
[2] Eurocode 8, Design of Structures for Earthquake Resistance, Part 2: Bridges. Brussels: European Standard EN 1998-2:2005, 2005.
[3] K. Kawashima, and J. Penzien, “Theoretical and experimental dynamic behavior of a curved model bridge structures,” Earthquake Engineering and Structural Dynamics, vol. 7, pp. 129-145, 1979.
[4] S. E. A. Raheem, “Pounding mitigation and unseating prevention at expansion joints of isolated multi-span bridges,” Engineering Structures, vol. 31, pp. 2345-2356, 2009.
[5] S. Banerjee, and M. Shinozuka, “Nonlinear static procedure for seismic vulnerability assessment of bridges,” Computer-Aided Civil and Infrastructure, vol. 22, pp. 293-305, 2007.
[6] S .A. Mitoulis, “Seismic design of bridges with participation of seat-type abutments,” Engineering Structures, vol. 44, pp. 222-233, 2012.
[7] N. Basoz, and J. Mander, Enhancement of the Highway Transportation Lifeline Module in HAZUS. National Institute of Building Sciences, 1999.
[8] H. Hwang, J. B. Liu, and Y. H. Chiu, Seismic Fragility Analysis of Highway Bridges. Report No. MAEC RR-4, Center for Earthquake Research Information, 2001.
[9] W. I. Liao, and C. H. Loh, “Preliminary study on the fragility curves for highway bridges in Taiwan,” Journal of the Chinese Institute of Engineers, vol. 27, no. 3, pp.367-375, 2004.
[10] E. Choi, R. DesRoches, and B. Nielson, “Seismic fragility of typical bridges in moderate seismic zones,” Engineering Structures, vol. 26, no. 2, pp. 187-199, 2004.
[11] E. Choi, J. Park, S.-J. Yoon, D.-H. Choi and C. Park, “Comparison of seismic performance of three restrainers for multiple-span bridges using fragility analysis,” Nonlinear Dyn., vol. 61, pp. 83-99, 2010.
[12] F. Nateghi, and V. L. Shahsavar, “Development of fragility and reliability curves for seismic evaluation of a major prestressed concrete bridge,” in Proc. 13th World Conference on Earthquake Engineering, Vancouver, B.C. Canada, 2004, Paper No. 1351.
[13] B. G. Nielson, “Analytical fragility curves for highway bridges in moderate seismic zones,” Ph.D. Thesis, Georgia Institute of Technology. Atlanta, Georgia, 2005.
[14] B. G. Nielson, and R. DesRoches, “Seismic fragility methodology for highway bridges using a component level approach,” Earthquake Engineering and Structural Dynamics, vol. 36, pp. 823-839, 2006.
[15] Ö. Avsar, “Fragility based seismic vulnerability assessment of ordinary highway bridge in Turkey,” Ph.D. Thesis, Middle East Technical University. Ankara, Turkey, 2009.
[16] M. S. Alam, M. A. R. Bhuiyan, and A. H. M. M Billah “Seismic fragility assessment of SMA-bar restrained multi-span continuous highway bridge isolated by different laminated rubber bearings in medium to strong seismic risk zones,” Bull Earthquake Eng., vol. 10, pp. 1885-1909, 2012.
[17] Eurocode 2, Design of Concrete Structures, Part 1-1: General Rules and Rules for Buildings. Brussels: European Standard EN 1992-1-1:2004, 2004.
[18] Eurocode 8, Design of Structures for Earthquake Resistance, Part 1: General Rules, Seismic Actions, and Rules for Buildings. Brussels: European Standard EN 1998-1:2003, 2003.
[19] PCI, Precast, Prestressed Concrete Bridges, the High Performance Solution. Comprehensive Bridge Design Manual, http://www.pci.org/publications/bridge, Accessed: 01/12/2014.
[20] OpenSees, Open System for Earthquake Engineering Simulation, Version 2.4.6, Pacific Earthquake Engineering Research Center, http://opensees.berkeley.edu/, Accessed: 23/09/2015.
[21] Computers and Structures, Inc. SAP2000 Nonlinear, Version 17.2.0. Structural Analysis Program, CA: Berkeley, 2015.
[22] M. J. N. Priestley, F. Seible, and G. M. Calvi, Seismic Design and Retrofit of Bridges. New York: John Wiley & Sons, Inc., 1996.
[23] Technical Manual, Reston Pendulum Curved Surface Slider. Mageba Seismic Protection Devices for Reliable Preservation of Structures, Mageba Inc., USA, 2015.
[24] M. C. Constantinou, P. Tsopelas, A. Kasalanati, and E. D Wolff, Property Modification Factors for Seismic Isolation Bearings. Multidisciplinary Center for Extreme Events Research, Technical Report MCEER-99-0012, Buffalo, New York, 1999.
[25] C. Casarotti and R. Pinho, “Seismic response of continuous span bridges through fiber-based finite element analysis,” Earthquake Engineering and Engineering Vibration, vol. 5, no. 1, pp. 119-131, 2006.
[26] J. B. Mander, M. J. N. Priestley, and R. Park, “Theoretical stress-strain model for confined concrete,” ASCE J. Structural Eng., vol. 114, no. 8, pp. 1804-1825, 1988.
[27] M. Menegotto, and P. E. Pinto, Method of Analysis of Cyclically Loaded RC Plane Frames Including Changes in Geometry and Non-elastic Behavior of Elements Under Normal Force and Bending. Preliminary Report IABSE, No. 13, 1973, pp.15–22.
[28] G. R. Saragoni, and G. C. Hart, “Simulation of Artificial Earthquakes,” Earthquake Engineering and Structural Dynamics, vol. 2, pp. 249-267, 1974.
[29] Seismosoft srl, SeimoArtif, Version 2.1.0, Earthquake Engineering Software Solutions, http://www.seismosoft.com. Accessed: 01/08/2014.
[30] M. J. Kowalsky, “Deformation limit states for circular reinforced concrete bridge columns,” ASCE J. Structural Eng., vol. 126, no. 8, pp. 869-878, 2000.
[31] HAZUS-MH MR1, Technical Manual, Vol. Earthquake Model. Washington DC: Federal Emergency Management Agency (FEMA), 2003.
[32] J. Zhang, Y. Huo, S.J Brandenberg, and P. Kashighandi, “Evaluation effectiveness and optimum design of isolation devices for highway bridges using the fragility function method,” Engineering Structures, vol. 31, pp. 1648-1660, 2009.
[33] Federal Highway Administration (FHWA), Seismic Retrofitting Manual for Highway Bridges. Report No. FHWA-RD-94-052, VA: McLean, 1995.
[34] K. Mackie, and B. Stojadinović, “Performance-based seismic bridge design for damage and loss limit States,” Earthquake Engineering and Structural Dynamics, vol. 36, no. 13, pp. 1953-1971, 2007.