TSUNAMI LOADING ON BUILDINGS WITH OPENINGS

Reinforced concrete (RC) buildings with openings in the masonry infill panels have shown superior performance to those without openings in the devastating 2004 Indian Ocean Tsunami. Understanding the effect of openings and the resulting tsunami force is essential for an economical and safe design of vertical evacuation shelters against tsunamis. One-to-one hundred scale building models with square shape in plan were tested in a 40 m long hydraulic flume with 1 m x 1 m cross section. A mild slope of 0.5 degree representing the beach condition at Phuket, Thailand was simulated in the hydraulic laboratory. The model dimensions were 150 mm x 150 mm x 150 mm. Two opening configurations of the front and back walls were investigated, viz., 25% and 50% openings. Pressure sensors were placed on the faces of the model to measure the pressure distribution. A high frequency load cell was mounted at the base of the model to record the tsunami forces. A bi-linear pressure profile is proposed for determining the maximum tsunami force acting on solid square buildings. The influence of openings on the peak pressures on the front face of the model is found to be practically insignificant. For 25% and 50% opening models, the tsunami forces reduce by about 15% and 30% from the model without openings, respectively. The reduction in the tsunami force clearly demonstrates the benefit of openings in reducing the effect of tsunami on such buildings

TSUNAMI WAVE LOADING ON A BRIDGE DECK WITH PERFORATIONS

Tsunamis have damaged bridges to various extents in the 2004 Indian Ocean Tsunami. This paper reports an experimental investigation of the effect of perforations in the girders and parapets on the horizontal tsunami loads. The results reveal that the maximum pressures impinging on the front face of the pier and deck are 4.5 and 3 times the hydrostatic pressure at 80mm nominal wave heights. The percentage of force reduction of the bridge deck with 10% perforated girders and 60% perforated parapets is found to be close to the percentage of perforation area in the deck. However, it is also noted that perforations in the bridge deck can substantially reduce the tsunami forces acting on it throughout the force time history. Thus, less damage to the bridge is anticipated for the bridge deck with perforations in girders and parapets

An assessment of the diversity in scenario-based tsunami forecasts for the Indian Ocean

This work examines the extent to which tsunami forecasts from different numerical forecast systems might be expected to differ under real-time conditions. This is done through comparing tsunami amplitudes from a number of existing tsunami scenario databases for eight different hypothetical tsunami events within the Indian Ocean. Forecasts of maximum tsunami amplitude are examined at 10 output points distributed throughout the Indian Ocean at a range of depths. The results show that there is considerable variability in the forecasts and on average, the standard deviation of the maximum amplitudes is approximately 62 of the mean value. It is also shown that a significant portion of this diversity can be attributed to the different lengths of the scenario time series. These results have implications for the interoperability of Regional Tsunami Service Providers in the Indian Ocean. © 2013 Elsevier Ltd