Influence of ground motion spatial variation, site condition and SSI on the required separation distances of bridge structures to avoid seismic pounding

Although post-earthquake observations identified spatial variation of ground motion (i.e., multiple-support excitation) as a frequent cause of the unfavorable response of long-span bridges, this phenomenon is often not taken into account in seismic design to simplify the calculation procedure. This study investigates the influence of multiple-support excitation accounting for coherency loss and wave-passage effects on the seismic response of reinforced concrete deck arch bridges of long spans founded on rock sites. Parametric numerical study was conducted using the time-history method, the response spectrum method, and a simplified procedure according to the European seismic standards. Results showed that multiple-support excitation had a detrimental influence on response of almost all analyzed bridges regardless of considered arch span. Both considered spatial variation effects, acting separately or simultaneously, proved to be very important, with their relative significance depending on the response values and arch locations analyzed and seismic records used. Therefore, it is suggested that all spatially variable ground-motion effects are taken into account in seismic analysis of similar bridges.

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Parameters Observation of Spatial Variation Ground Motion

Computational Structural Engineering ◽

10.1007/978-90-481-2822-8_35 ◽

2009 ◽

pp. 309-317 ◽

Cited By ~ 1

Author(s):

Yanli Shen ◽

Qingshan Yang ◽

Lingyan Xuan

Keyword(s):

Spatial Variation ◽

Ground Motion

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V S30, slope, H 800 and f 0: performance of various site-condition proxies in reducing ground-motion aleatory variability and predicting nonlinear site response

Earth Planets and Space ◽

10.1186/s40623-017-0718-z ◽

2017 ◽

Vol 69 (1) ◽

Cited By ~ 17

Author(s):

Boumédiène Derras ◽

Pierre-Yves Bard ◽

Fabrice Cotton

Keyword(s):

Ground Motion ◽

Site Response ◽

Site Condition ◽

Nonlinear Site Response ◽

Aleatory Variability

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Response of Long-Span Concrete Filled Steel Tubular Arch Bridge Subjected to Spatially Varying Ground Motion

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.243-249.1512 ◽

2011 ◽

Vol 243-249 ◽

pp. 1512-1517

Author(s):

Zhong Quan Zou ◽

Li Ping Zhou ◽

Guo Jing He

Keyword(s):

Wave Propagation ◽

Spatial Variation ◽

Ground Motion ◽

Dynamic Equilibrium ◽

Time History ◽

Correlation Effect ◽

Arch Bridge ◽

Spatially Correlated ◽

Long Span ◽

Wave Passage

The responses of a long span concrete filled steel tubular (CFST) arch bridge subjected to spatially correlated ground motion are analyzed. By using the stochastic vibration method, the time history of ground motion on the bridge site is simulated. The influences of spatial variation of the ground motion, such as uniform excitation, wave passage effect and partial correlation effect on seismic responses are studied based on the dynamic equilibrium equation for multi-support excitations. The calculated results show that the wave propagation influences the internal forces of the arch significantly. The effect of partial coherency is more complex compared to that of the wave propagation, yet it can be neither neglected. For long-span CFST arch bridges, it is critical to consider the effects of the spatial variation of ground motion.

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Seismic design of bridge structures with allowance for large relative girder movements to avoid pounding

Bulletin of the New Zealand Society for Earthquake Engineering ◽

10.5459/bnzsee.42.2.75-85 ◽

2009 ◽

Vol 42 (2) ◽

pp. 75-85 ◽

Cited By ~ 9

Author(s):

Nawawi Chouw ◽

Hong Hao

Keyword(s):

Ground Motion ◽

Soil Structure ◽

Influence Factors ◽

Bridge Girders ◽

Gap Size ◽

Expansion Joint ◽

Vibration Properties ◽

Bridge Structures ◽

Almost All ◽

Bridge Spans

Pounding between bridge girders have been observed in almost all previous major earthquakes. This is because the gap size of conventional bridge expansion joint is usually only a few centimetres, which is not sufficient to preclude poundings owing to large relative displacements between bridge girders caused by the effect of varying vibration properties of adjacent bridge spans, varying ground motions at bridge supports and varying soil-structure interaction (SSI). In this work a new design of bridge expansion joint is introduced. Instead of tolerating pounding and providing possible mitigating measures, this new design approach enables large movement between bridge girders which makes a complete pounding preclusion possible. The new expansion joint is called Modular Expansion Joint (MEJ). The large movability is achieved by installing a number of small gaps in the joint. In this study, the MEJ gap size required to completely avoid girder pounding is investigated. The most significant influence factors – the varying vibration properties of adjacent bridge spans, the effect of SSI and ground motion spatial variation on expansion joint size required to preclude pounding- are calculated. Discussions on the relative importance of various structural and ground motion properties in generating relative displacements of adjacent bridge girders are made.

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