Dynamic characteristic measurement of precast and cast in-situ walls in abandoned high-rise building using ambient and forced vibration methods

This study evaluates the dynamic characteristics of an abandoned reinforced concrete building with structural deterioration and defects in its precast and cast in-situ walls. Using ambient vibration and forced excitation, the dynamic characteristics (i.e., modal frequency, modal damping, and strain patterns) were extracted to evaluate existing performances. Then, the numerical modal analysis was conducted with the dynamic properties at the initial service stage since the joint degradation was not accounted. In general, modal frequency obtained from field measurement was approximately 19.8%-20.8% smaller than that obtained from the numerical analysis, indicating the degraded stiffness due to existing cracks at joint connections. In addition, the measured strain patterns and neutral axis location were eventually compared with the analytical results, proving the potential indicators for identifying local imperfections of the targeted high-rise buildings.

Automated summary

This study evaluates the dynamic characteristics of an abandoned reinforced concrete building with structural deterioration and defects in its precast and cast in-situ walls. Using ambient vibration and forced excitation, the dynamic characteristics (i.e., modal frequency, modal damping, and strain patterns) were extracted to evaluate existing performances. The results show that the measured modal frequency was smaller than the numerical analysis, indicating degraded stiffness due to existing cracks at joint connections. The measured strain patterns and neutral axis location were also compared with the analytical results, providing potential indicators for identifying local imperfections.