Study on Seismic Retrofitting and Effect Evaluation of a School Building after the Eastern Japan Earthquake
Computational analysis and experimental study were performed on the strengthening of a school building in Japan after the earthquake in 2011 in eastern Japan.First of all,the structural characteristics and seismic appraisal results of the currently existing school buildings were expounded.Then,a strengthening scheme was proposed:the strength was improved by using a longitudinal steel braced frame and adding transverse shear walls on the first floor.Next,a wireless vibration test system was used to perform the microtremor determination experiments to the school building before and after the strengthening.Moreover,the changes of the parameters like the acceleration spectrum,inherent period,and vibration mode of the school building were analyzed from both global and local perspectives.Finally,the computational simulation and test results were comparatively analyzed,the seismic strengthening method and the influence of the strengthening position on the original building were expounded,and the effect of this seismic strengthening method was verified.Results show that the strengthening method with a steel braced frame can improve the strength of the existing school building,the acceleration response value after the strengthening declined to about 1/3 of that before the strengthening.The changes in the inherent period and the amplification factor of acceleration response accord with those of the seismic strengthening method for this school building,indicating that the research method based on the vibration test can effectively evaluate the strengthening effect of seismic strengthening work.The study results may provide a reference for the selection and evaluation of seismic strengthening schemes of the existing school buildings.
vibration and waveschool buildingsteel braced frameretrofittingmicrotremor observationstructural calculation