Characteristics of Building Seismic Damages in M_s6.4 Yangbi Earthquake Affected by Ground Motion Directivity and Site Condition

After the M_s6.4 earthquake in Yangbi,Yunnan,on May 21,2021,the seismic damage survey,mobile strong motion observation of aftershocks,and characteristic analysis of ground motion and building damage were carried out.The characteristics of building damage in the earthquake-stricken region especially in the meizoseismal area were summarized,the correlation between the building damage and the ground motion characteristics was explored,the effect and mechanism of topographic condition and ground motion directivity on the building seismic damage characteristics and disaster distribution were revealed.Due to the topographic effect of local site,buildings located on the steep slope and the top of mountains were encountered more severe damage than those on the mountain foot.The directivity effect of ground motion is the main reason for the damage difference of buildings with different orientations.By summarizing the seismic damage characteristics in this earthquake,measurements and suggestions for improving the seismic performance of the mud and wood houses in Yunnan Province were proposed.