Study On Dynamic Characteristics Of Historic Buildings

Historic building is a carrier of the urban development, which has high value ofarchitectural art and historical culture. According to the data of their dynamiccharacteristic tests, and combined with the current seismic design code and appraisalstandard, a comprehensive analysis and study on dynamic characteristics of the threehistoric buildings was made. The main content and related conclusions are listed asfollows.1. Firstly, dynamic characteristic tests of the three buildings were carried out, andthe fore several frequencies and shapes of vibration were gained. Afterwards, we caninfer the three buildings are in a good overall stability, with no obvious defectsaccording to the test data.2. According to the tested frequencies and shapes of vibration, the whole stiffnessmatrixes of the three buildings were obtained through inversion analysis. Thenthrough concentrated mass method, the measured values of their floor lateral stiffnesswere gained. Finally, a contrast analysis between the measured values and thetheoretical values was made, and the measured value increased by about15%than thetheoretical value. Therefore, this paper considers that the simplified method on thecalculation of floor lateral stiffness in the current seismic design code is worth todiscuss, which an actual space model is simplified to the plane model with thelongitudinal and transverse directions.3. According to the two-stage appraisal method of compound seismic capabilityof multi-story masonry building in the current seismic appraisal standard, the seismicappraisals of the three buildings were made. Considering spatial cooperation impactof longitudinal wall, transverse wall and floor, namely considering the existence ofthe wing wall on the calculation of seismic capacity index in the second levelappraisal, the seismic appraisals of the three buildings were made again. We foundthat the results of the last met better with the actual situation. As a consequence, thispaper suggests that spatial cooperation impact should be considered in the seismicappraisal of multi-story masonry building in the current seismic appraisal standard.4. According to the first measured amplitude, the in-plane deformation in thewooden floors of the three buildings was narrated firstly. Then the relationshipbetween the in-plane deformation and the in-plane stiffness in the wooden floor was analyzed in details. Finally, combined with the above results that the wooden floorcould effectively transfer seismic action, this paper thinks that the practice that theusage of wooden floor is not suitable in the current seismic design code isquestionable.5. According to the two-stage appraisal method of compound seismic capabilityof multi-story masonry building in the current seismic appraisal standard, the firstlevel appraisals of the three buildings were made firstly. Afterwards, combined withthe floor comprehensive seismic capacity indexes of the three buildings，the mainfactors of overall seismic performance of historic buildings were analyzed fromthe structural requirements. Finally, we conclude that the main factors are the heightof the building and layer number, the plane and elevation layout, the distance betweenseismic cross walls, the overall joint construction, not the strength grade of masonrymortar.