Effects of structural characterizations on fragility functions of bridges subject to seismic shaking and lateral spreading

This paper evaluates the seismic vulnerability of different classes of typical bridges in California when subjected to seismic shaking or liquefaction-induced lateral spreading. The detailed structural configurations in terms of superstructure type, connection, continuity at support and foundation type, etc. render different damage resistant capability. Six classes of bridges are established based on their anticipated failure mechanisms under earthquake shaking. The numerical models that are capable of simulating the complex soil-structure interaction effects, nonlinear behavior of columns and connections are developed for each bridge class. The dynamic responses are obtained using nonlinear time history analyses for a suite of 250 earthquake motions with increasing intensity. An equivalent static analysis procedure is also implemented to evaluate the vulnerability of the bridges when subjected to liquefaction-induced lateral spreading. Fragility functions for each bridge class are derived and compared for both seismic shaking （based on nonlinear dynamic analyses） and lateral spreading （based on equivalent static analyses） for different performance states. The study finds that the fragility functions due to either ground shaking or lateral spreading show significant correlation with the structural characterizations, but differences emerge for ground shaking and lateral spreading conditions. Structural properties that will mostly affect the bridges＇ damage resistant capacity are also identified.

Disaster Risk Management Through the Design Safe Cyberinfrastructure

Design Safe addresses the challenges of supporting integrative data-driven research in natural hazards engineering.It is an end-to-end data management,communications,and analysis platform where users collect,generate,analyze,curate,and publish large data sets from a variety of sources,including experiments,simulations,field research,and post-disaster reconnaissance.DesignSafe achieves key objectives through:(1)integration with high performance and cloud-computing resources to support the computational needs of the regional risk assessment community;(2)the possibility to curate and publish diverse data structures emphasizing relationships and understandability;and(3)facilitation of real time communications during natural hazards events and disasters for data and information sharing.The resultant services and tools shorten data cycles for resiliency evaluation,risk modeling validation,and forensic studies.This article illustrates salient features of the cyberinfrastructure.It summarizes its design principles,architecture,and functionalities.The focus is on case studies to show the impact of Design Safe on the disaster risk community.The Next Generation Liquefaction project collects and standardizes case histories of earthquake-induced soil liquefaction into a relational database—Design Safe—to permit users to interact with the data.Researchers can correlate in Design Safe building dynamic characteristics based on data from building sensors,with observed damage based on ground motion measurements.Reconnaissance groups upload,curate,and publish wind,seismic,and coastal damage data they gather during field reconnaissance missions,so these datasets are available shortly after a disaster.As a part of the education and community outreach efforts of Design Safe,training materials and collaboration space are also offered to the disaster risk management community.