Earthquake Risk Assessment of Bridge Based on Failure Probability Method

To study the possibility of destruction of a high-speed railway continuous girder bridge under the influence of seismic damage, a seismic risk assessment of the bridge was conducted. The failure probability method was used, in which seismic risk is defined as the product of seismic hazard and fragility (i.e., seismic risk=seismic hazard×fragility). The bridge seismic demand model was established using the strip coating method. The bridge seismic fragility curve was obtained based on the reliability function, and the probability density function of the bridge fragility was fitted. According to seismic risk data of the bridge site, the probability density function of seismic acceleration of the bridge site was derived. The probability density function of seismic acceleration was numerically integrated with that of the bridge structural vulnerability to accomplish the probability evaluation of the bridge earthquake risk. Taking a (32+48+32) m high-speed railway continuous girder bridge as an example, the system conducted the bridge risk assessment using the failure probability method. The results show that when earthquake risk data are lacking or insufficient, it is possible to deduce and improve seismic risk analysis data using the conversion relation between the earthquake intensity distribution function and the seismic peak acceleration. For the high-speed railway (32+48+32) m continuous girder bridge, within 100 years of use, the occurrence probability of slight damage is 5.16% and that of secondary damage is 4.46%. The probabilities of slight damage and secondary damage risk of the bridge are similar, whereas the probabilities of serious damage and complete destruction are very small, indicating that serious damage and complete destruction are almost impossible.