Development of Damage Evaluation Techniques for Geotechnical Structures(II)–A Case Study of the old Jhong-Jheng Bridge in Hsinchu

Development of Damage Evaluation Techniques for Geotechnical Structures(II)–A Case Study of the old Jhong-Jheng Bridge in Hsinchu

This report presents a verification of damage evaluation techniques for geotechnical structures based on structural dynamic responses developed in previous years through an actual case study. In Taiwan, several failures of highway bridges related to foundation scour occurred in recent years, which have caused considerable casualties and property loss. Therefore, the focus of this study is on the damage evaluation of bridge foundations, and the old Jhong-Jheng Bridge in Hsinchu, of which the caisson foundations have suffered severe exposure due to scouring, was adopted as the object of study. Firstly, microtremor measurements were made on the superstructure of the bridge, and the influence of foundation scouring was revealed by spectrum analysis and modal analysis. In addition, because the design drawings were unavailable and the foundation depth is thus unknown, the impulse response method was utilized to estimate the depth of the caisson foundation and a satisfactory result was obtained. According to all the above results, the feasibility of the non-destructive testing methods in the damage evaluation of structural foundations can be validated.