Tsunami Analysis of Structures: Comparison Among Different Approaches

Abstract eng:
The widespread damage caused by past tsunami, e.g. 2004 Indian Ocean Tsunami and 2011 Great East Japan tsunami, has motivated several research activities in tsunami engineering. The behaviour of buildings subjected to tsunami actions has received particular attention. Some studies have been published regarding the estimation of tsunami action; many papers, as well as existing building codes suggest modelling the tsunami-structure interaction with an equivalent force approach. These literature papers propose that the tsunami force and its distribution along the height of the structure are strictly related to the features of the tsunami flow, e.g. flow velocity and inundation depth. However, there is a lack of published literature concerning the analysis methodologies to adopt for estimating the response of buildings to these tsunami loads. A question therefore arises as to which analysis method is the most appropriate in the case of tsunami inundation of buildings and whether the nonlinear static analysis method, commonly used in earthquake engineering, is suitable for this case. This paper presents a study aimed at shedding light on analysing buildings subjected to actions due to tsunami inundation. In particular, three different analysis methodologies of constant-height pushover (CHPO), variable-height pushover (VHPO), and time-history (TH) analyses are compared in terms of their abilities to predict structural response. An existing 10-storey reinforced concrete tsunami evacuation building in Japan is considered as case study. A distributed plasticity approach is adopted to model the RC frame structure. Two different load patterns, i.e. triangular and trapezoidal, are adopted to distribute the tsunami force along the height of the structure. The two pushover analysis methodologies, i.e. CHPO and VHPO, are compared to TH analysis in terms of their abilities to predict structural response for an extensive set of simulated tsunami inundation time-histories. It is found that the results of VHPO provide a good prediction of the engineering demand parameters obtained from the TH analysis under a wide range of tsunami time-histories. CHPO gives a worse prediction of the demand; it overestimates interstorey drift ratio and underestimates column shear by about 5-20%. It is concluded that pushover methods are a good proxy for TH. In particular, it is recommended that VHPO be used in future analysis of buildings subjected to tsunami. It should be also highlighted that pushover methods may be inadequate in cases where the tsunami inundation force time-history is characterised by a double-peak, which subjects the structure to a twocycle load.

• Export as: BibTeX | MARC | MARCXML | DC | EndNote | NLM | RefWorks
• Add to your basket