Study On Cumulative Damage In Fatigue Of Building Structures Caused By Mine-quakes

Mineral earthquake is a kind of seismic activities caused by mining. Research on effect of mineral earthquake on building structures to diminish and control the damage is of great importance for national economy and people's safety. At present, the intensity designed for buildings and structures is divided according to natural earthquake intensity, that is, to ensure the structures can sustain a strong earthquake without collapsing, a moderate earthquake with repairable structural damage, and a minor earthquake without any damage. But for buildings and structures experiencing frequent mineral earthquake, there is no code to follow. Based on Fu Shun mineral earthquake and the motoring data from Fu Shun earthquake bureau, rules of frequent mineral earthquake and its cumulative damage in fatigue are studied in this dissertation. The main works done are as follows:(1) Time series feature of b value in mineral earthquake and its energy creep curve are analyzed. It is found that the scale and intensity of Fu Shun mineral earthquake tends to increase. From analysis of distribution laws of 1st magnitude frequency mineral earthquake, 1st grade frequency mineral earthquake in Fu Shun conforms to the G-R relation. Study on attenuation relations for seismic intensity in mineral earthquake source show that oval-shaped model with long-axis and short-axis attenuating respectively can apply to Fu Shun mineral earthquake intensity. And the relevant coefficients are presented as well.(2) Mineral earthquake predictive model based on improved fuzzy neural network is established. For the first time, the greatest magnitude is predicted using the fuzzy neural network. The results are compared well with those obtained from real monitoring. It paves a new way for predicting mineral earthquake.(3) Using BAQ—PI—321 seismic testing instrument equipped with seismometer, dynamic testing technique is for the first time carried out real test to determine the influence of mineral earthquake on urban buildings. A residential building at Yu Lin Road in Fushun is analyzed. From the results of twice test, it is found that the inherent vibration period and drift displacement of the building increase. While story stiffness , story strength, story stress and story shear all diminish. It demonstrates that seismic resisting capacity of buildings is on the decline under frequent mineral earthquake.(4) Experimental study is done of the column specimen under horizontal low reversed cyclic loading. With various axial compression ratio, the failure process and form, characteristic of resilience, skeleton curve, steel strain, etc. are studied.(5) From viewpoint of engineering damage, the process of damage in fatigue of building structures under frequent mineral earthquake is studied. Started from rotation factor of the structural component's end intersection, the damage model of the components is constructed under frequent mineral earthquake. The damage index of reinforced concrete components is defined and standardized. Using linear weighted summation, the damage model of reinforced concrete frame is constructed under frequent mineral earthquake.(6) An artificial designed cycle loads is adopted to simulate the mineral earthquake loads. FEA analysis software ADINA is for the first time used to simulate the damage evolution of the reinforced concrete frame, and has the conclusion:the damage evolution curve trend of each Component is similar; the damage of the structure and components is growing as the cyclic load goes on; the Natural frequency of the structure reduced when Imposing cyclic loading; the damage of the beam component is further than that of the column component through numerical analysis and it provides the reference for the Earthquake Prevention.