When conducting the seismic response analysis on a long elevated structure, if the transmitting boundary is set at both ends of the analysis region, there is a condition that the response becomes larger than in the case of the free boundary. In this research, we studied the influence of the effective duration time of earthquake motion on the maximum displacement amplitude of earthquake response and the response energy of earthquake when carrying out similar analysis using viscous boundary. As a result, it was confirmed that the correlation between the effective duration and the relationship between the viscous boundary and the maximum displacement amplitude ratio of the free boundary is low. On the other hand, for the relationship between the effective duration time and the response energy ratio between the viscous boundary and the free boundary, the variance was small and a certain correlation was confirmed.

Extended Accumulated SIBIE in order to improve the limit of visibility of Accumulated SIBIE method is a method to significantly improve the performance of measurements by extension the region of visibility to a low-frequency region. Decrease of resonant frequency displayed in the lower frequency region than the thickness frequency is due to reduction in rigidity by essentially degradation and cross-sectional loss of members. It is necessary to clarify the relationship between the resonance frequency and the deterioration or damage patterns to learn these patterns. In this research, by obtaining the vibration mode and the natural frequency by the eigenvalue analysis, it was confirmed that dynamic analysis which take time and effort can be minimized.

Image created by stack imaging spectral amplitudes based on the impact-echo (SIBIE) method is largely one-dimensional because a single frequency domain spectrum for wave reflected below a single point of impact is used to create the image. The method has limitations for representing defects in a cross section of a concrete structural element using two-dimensional coordinates. This study focused on defect detection and visualization in a concrete structural element using multiple impacts and accumulated SIBIE. An impactor was used to induce energy at multiple points at positioned at prescribed intervals along the structural element. A modified SIBIE method was applied to the collected data of each point and the modified SIBIE images were accumulated to generate one image (an accumulated SIBIE image). As a result, the defect positions could be represented in the cross section of the structural element using a two-dimensional coordinate system.