Preventing the fall of skew and curved bridge decks during earthquake and predicting the pounding response

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During the Hyougo-Ken-Nanbu earthquake in 1995 and Northridge earthquake in 1994, many decks in skew and curved bridges collapsed. The research dealt with preventing the fall of deck structures by the means of supporting the bridges by rubber bearings and permitting pounding between the decks and the abutments. The crucial point in the research is to clarify the pounding phenomena and the result can predict damage level of deck ends and abutments and can verify the possibility of the proposed means.From the simulation analyses and the experiments, the research indicated that the pounding between deck and the abutments is a chaos phenomenon but has similarity between the three quantities of input intensity, clearance and response of a deck. Particularly, the clearance is most dominant in determining the maximum response and frequency characteristics of a deck and earthquake wave do not much influence the response.Since pounding of a deck is a chaotic phenomenon, time history of the response is not reliable but the maximum is rather important in an engineering viewpoint. Even if the response is chaotic, the maximum is governed by energy principle and is predicable. Therefore, the study proposes a predicting equation that satisfies the similarity between the three quantities. When comparing the predicting equation with simulated results and experimental results, the equation well agrees with them. Hence, the predicting equation can estimate the damage level of deck end and abutment during earthquake and can verify the effectiveness of shock absorber developed without simulating the pounding by using complicated model of collision.