Contribution of Trapped Air, Deck Superelevation, and Nearby Structures to Bridge Deck Failure during a Tsunami

Tsunami Induced Forces in Bridges: Large-Scale Experiments and the Role of Air-Entrapment

“…When it comes to the magnitude of the pressure the air entrapment seems to have a minor effect on the horizontal pressure and a major effect on the vertical pressure on the deck, with ST5 witnessing approximately 3 times higher vertical pressures due to the air entrapment. In addition, the air entrapment seems to be smoothing out the peaks of the pressure histories and increase their duration, as was also seen in the experimental study by Cuomo et al (2009). Figure 13 shows the horizontal forces (left graph) recorded in the link and the total vertical forces recorded in the bent cap connections (right graph).…”

“…These events demonstrated the vulnerability of coastal bridges to tsunami waves and triggered the response of the research community in an attempt to improve the understanding of tsunami inundation and the effects on structures. Several interesting studies have been conducted to date including (i) on-site surveys and damage analysis (Kosa 2012, Kawashima 2012, Kawashima and Buckle 2013 (ii) small-scale experiments in wave flumes (Hayashi 2013, Lau et al 2011, Maruyama et al 2013 and (iii) numerical simulations (Hayatdavoodi et al 2015, Bricker and Nakayama 2014, Kataoka and Kaneko 2013, Yim et al 2011, Azadbakht 2013, Istrati and Buckle 2014. On-site investigations analyzed the failed bridges and revealed that the overflow can occur either in the form of transverse drag due to large horizontal wave forces or in the form of uplift and overturning due to the combination of large vertical and horizontal tsunami forces (Kawashima 2012, Kawashima andBuckle 2013).…”

“…He developed predictive force equations where he considered additional buoyancy due to the existence of air, assuming that 50% of the volume between girders were filled with air. Bricker and Nakayama (2014) who studied numerically the tsunami inundation of Utatsu Bridge in Japan, revealed that the trapped air between the girders increased the buoyancy of the bridge deck significantly resulting in the failure of the bridge. noted that the trapped air increases the pressures below the bridge however it has not only a hydrostatic but also a hydrodynamic effect.…”

“…noted that the trapped air increases the pressures below the bridge however it has not only a hydrostatic but also a hydrodynamic effect. Cuomo et al (2009) conducted hydraulic experiments of a bridge at 1:8 scale and observed that the holes in the bridge deck reduced the wave pressures on the deck slab but increased the ones on the longitudinal beams. The authors also noted the compression of the trapped air during the wave inundation acting as cushioning that reduces the max impulsive load and increases the load duration.…”

Study on the Evaluation of Temporal Change in Horizontal and Vertical Tsunami Forces Acting on a Bridge Superstructure

“…In the 2011 Tohoku earthquake, 12 of 151 bridge superstructures in tsunami-affected areas on Japanese national roads directly maintained by the Tohoku Regional Bureau, the Ministry of Land, Infrastructure and Transport of Japan were washed away due to an earthquaketriggered tsunami [e.g. Muhari et al, 2012;Bricker and Nakayama, 2014;Shoji and Nakamura, 2014;JSCE, 2015]. Such bridge superstructures damaged by a tsunami can be obstacles to post-disaster activities for rehabilitation and reconstruction in devastated areas.…”