Seismic Response And Fragility Analysis Of High-rise Structures Under Long-period Ground Motion

In recent years,with the continuous development of China’s economy,various high-rise and super high-rise buildings have emerged in an endless stream.Long-period ground motions are ground motions with significant low-frequency components.In recent years,reports have pointed out that long-period ground motions have caused more serious damage to high-rise and super high-rise structures with larger natural vibration periods than ordinary ground motions.Moreover,in my country’s seismic design code,there is no specific regulation on how to control the more serious damage that may be caused by long-period ground motions.This paper proposes a convolutional neural network model that can quickly and accurately identify long-period ground motions,analyzes the response of high-rise structures under long-period ground motions,and analyzes the structural seismic vulnerability of structures under long-period ground motions.And calculated the loss of structure.Specifically completed the following research content:From the literature,1,320 long-period ground motions recognized worldwide were selected,and 1,320 ordinary ground motions were selected,and the ground motions were corrected and filtered.The distributions of PGA,PGV,PGD,PGV/PGA,PGD/PGV values of far-field,near-field long-period ground motions and ordinary ground motions are respectively analyzed.Earthquake: Perform Fast Fourier Transform(FFT)and normalize the Earthquake,and use the obtained data as training data for deep learning.A convolutional neural network for identifying long-period ground motions is built,and the recognition of long-period ground motions is realized,and the recognition accuracy is higher than traditional methods.The 19-story and 52-story steel structure frames were built and modal analysis was performed.Two typical far-field,near-field long-period and ordinary ground motions are selected,and the 19-story and 52-story structures are compared and analyzed under the effects of long-period and ordinary ground motions under frequent and rare conditions respectively.The results show that under the action of long-period ground motions,the structure will produce greater displacement,interlayer displacement angle and acceleration response than ordinary ground motions,and the improvement of displacement response is more obvious than acceleration response.IDA(incremental dynamic analysis)is carried out on 19-story and 52-story steel structures.According to the results of incremental dynamic an alysis,the seismic vulnerability curve of the structure is obtained.The results show that the failure probability of the structure under the action of long-term ground motion in the far field is greater than that of the near-field long-cycle earthquake Under the action of near-field long-period ground motion,the damage probability of structure is greater than that of ordinary ground motion.The probability density curves of different failure states of the 19-story and 52-story structures are calculated,and the average loss rate of the structure under different ground motions is obtained.The results show that long-period ground motions will cause greater loss to high-rise and super high-rise buildings.