Elastoplastic TFRS And TFRS Analysis Method For Structural Dynamic Analysis

The earthquake ground motion is characterized by its three tightly correlated attributes: amplitude, frequency content, and duration. Its panorama can hardly be viewed from a single perspective. Currently, Response Spectrum Analysis (RSA) is the most popular method of dynamic response analysis. In a customary response spectrum curve, the maximum response value, i.e. acceleration, velocity, and displacement, is a function of only period. However, one of the significant shortcomings of the current elastic as well as inelastic design spectrum is the fact that it does not account for the duration of the input ground motion. Time-Frequency Response Spectrum (TFRS), whose response value is a function of not only period but also time, addresses this drawback. With its advantage of considering the effect of earthquake duration, it is possible for TFRS to analyze structural damage mechanism and damage accumulation effect under earthquake attacks. As a recently developed analysis method, although it has promising prospects, research with reference to it remains short. In order to picture the nexus of the three interrelated characteristics in an earthquake ground motion more comprehensively, by penetrating into TFRS, this thesis aims to develop a more rational analysis method for structural dynamic analysis. Cataloged by contents, this thesis can be outlined as the following parts.In chapter 1, the emerging background of TFRS is reviewed and its research necessity is presented.In chapter 2, the concept, fundamental, and creating procedure of TFRS is introduced. Several typical earthquake ground motions are applied to create their own time-frequency response spectrums. Finally, the impact of damping on it is analyzed.In chapter 3, attention is put on elastoplastic time-frequency response spectrum. Its concept, fundamental, and creating procedure is specified. How the yielding displacement influences it is anatomized.In chapter 4, studies are given to the application of TFRS in estimating the seismic response of multi-degree-of-freedom structures. The computing accuracy between response spectrum analysis method and time-frequency response spectrum analysis method to calculate the seismic responses of two testing examples is compared. A modal combination method that considers time correlation is proposed.In chapter 5, efforts are paid to retrospect the work completed in this thesis and point out the research that can be further conducted.Principal contributions of this thesis to TFRS can be summarized as follows.(1) Elastoplastic time-frequency response spectrum is proposed for the first time. Its creating procedure is also presented.(2) Attempt is made to employ TFRS to evaluate the seismic response of multi-degree-of-freedom structures. A modal combination method that considers time correlation is also proposed.