Research On The Earthquake Vulnerability Of Masonry Structure And Its Application To Insurance

With a long history,the masonry structure is a kind of building structure form which is distributed broadly in the rural area and suburb towns.It has been showed that the masonry structure could suffer the greatest losses in earthquake due to its lower seismic behavior.Making an earthquake vulnerability analysis for the masonry structure could get the fragility curves and the vulnerability matrixes,evaluate the seismic behavior of structure quantitatively and predict the loss due to earthquake damage.The loss caused by earthquake is always disastrous,so the relief way from governmental financial supervision is unsustainable.The earthquake vulnerability analysis could be applied not only to reasonably determine the insurance rate of earthquake,but also to design and complete the earthquake insurance system adapted to the situation in our country.Concentrating on earthquake vulnerability of masonry structure and its application to insurance,the main work done in this thesis is as following:(1)Based on available earthquake damage prediction data,weight of the building layer,age and use into earthquake damage matrix is calculated by entropy method in this paper.With the help of Euclidean distance and nearness degree in fuzzy mathematics,the analogy analysis model founded on the earthquake damage matrix is established for rapid prediction of earthquake damage in Panzhihua area.(2)Based on feature of shear failure within masonry structure and study of equivalent bar elements,the wall of masonry structure is simplified to three spring element with a certain degree of accuracy and high practicality.By calculating the experimental data about the masonry wall at home,the parameter calibration of the Lu-Qu restoring force mode and the hysteretic rule have been finished,which is suitable for masonry structure.(3)Based on model of three spring element,the numerical model of the masonry walls with common solid,structural column and the opening are established respectively.The simulation results show that the hysteresis curve and skeleton curve agree well with the experimental data.Further,the degenerate laws of strength and stiffness are more consistent and the characteristics of pinch and slipping also conform to the testing.Based on the test using platform vibrator and the data of entity modeling,the modality of three-spring model has been validated.It shows that their vibration mode is closed to natural frequencies.So,the three-spring model could be applied to nonlinear dynamic time history analysis on masonry structure.(4)The finite element numerical model of masonry structure is established in Marc software platform by using the three-spring model.In order to analyze the earthquake vulnerability of masonry structures with 24 seismic waves,the PGA is regarded as intensity index of ground motion and the inter-story displace is regarded as vulnerability damage control index.The fragility curves and the vulnerability matrixes show that the code of “no damage in minor earthquake”,“repairable in moderate earthquake” and “no fail in major earthquake” could be reached for the numerical masonry model.(5)Considering the influence of opening rate,the layout of structural column and the number of stories for masonry seismic behavior,the earthquake vulnerability is calculated respectively and the regularity caused by this factory is concluded quantitatively.The result shows that the above three factories have an enormous effect on earthquake vulnerability which should be concerned by designers.(6)The risk sharing system with three levels which are involved in the insurance company,the escrow company and the government is established.Based on curve of vulnerability,the seismic insurance rate of the structure is computed.According to the result,the total rate,deductible rate and compensate expression of earthquake insurance are given in this paper.The result shows that the insurance rate has a great relationship with the seismic vulnerability of the structure,and its value will increase with the increase of seismic vulnerability.