Seismic Risk Assessment of Wooden Structures Near Faults Considering the Locational Uncertainty of Source Area Using the Non-Uniform Slip Model


Abstract eng:
Although the magnitudes of inland earthquakes are smaller than those of earthquakes in subduction zones, they have caused catastrophic disasters in the past. Seismic damage to structures strongly depends on the geometric relationship between a fault and the structure itself, especially near a fault. In recent years, the locations and activities of inland active faults have been identified in Japan. However, the position of a rupture-starting point and rupture extent are uncertain. Together with this uncertainty, we have to consider the difference in the seismic performances of structures, upon which the extent of damage also depends. In this study, seismic ground motions near a fault were simulated with consideration of the abovementioned uncertainty, and the geometric distribution of the damage probability of wooden structures near a fault was investigated. The effect of seismic performance was also investigated. First, the ground motion with directivity on an engineering bedrock was simulated with a non-uniform slip model of an earthquake-source fault using the stochastic Green’s function. Element seismic waves overtook the phases of neighboring waves. Then, a rupture-starting point was decided stochastically and we assumed that the location of the earthquake-source fault followed a uniform distribution in the possible range. Ground motion on the surface was created by inputting the ground motion into a surface-layer model composed of loam using the one-dimensional equivalent linear analysis. If the maximum shear strain was over 5% in the response analysis result, we trimmed the input waves to maintain their reliability. Wooden structures were modeled considering the restoring force characteristics in accordance with the criteria of three seismic grades. Time-history response analysis was carried out by inputting the ground motion to the building model. Binomial discrimination as to whether or not damage occurred was conducted on the basis of the maximum story drift angle of the building models. Using the results of binomial discrimination, fragility curves assuming a lognormal distribution were constructed for each site using a maximum-likelihood method. Here the peak ground velocity was used as a ground-motion intensity parameter. A stochastic model of earthquake occurrence time was defined in consideration of the uncertainty of the earthquake scale, assuming a stochastic model for the variation of the slip quantity of the earthquake-source fault. We used a Brownian passage time distribution for making these models. Hazard curves of the ground motion were evaluated by this probability model. Finally, the earthquake damage probability of wooden structures was calculated for each site based on the fragility curve and the hazard curve mentioned above. As a result, the influence of the geometric relationship between a fault and the wooden structures and the seismic performance on the earthquake damage probability was obtained. The damage probability of wooden structures was significantly higher in the vicinity of the center of the possible range of the earthquake-source fault. In the vicinity of the fault, earthquake damage probability was reduced more effectively by changing the seismic grade from 1 to 2 than from 0 to 1.

Contributors:
Conference Title:
Conference Title:
16th World Conference on Earthquake Engineering
Conference Venue:
Santiago (CL)
Conference Dates:
2017-01-09 / 2017-01-13
Rights:
Text je chráněný podle autorského zákona č. 121/2000 Sb.



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 Record created 2017-01-18, last modified 2017-01-18


Original version of the author's contribution as presented on USB, paper 4637.:
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