Special Section on Performance of Bridges under Critical Natural Hazards

In recent years, extreme monsoon events and devastating earthquakes have caused serious damage to infrastructure, including bridges. Failures of bridges not only result in threats to vehicles and people traveling on them at the time of the failure but also interrupt emergency evacuation and rescue traffic, increasing the severity of the disaster and adding to casualties and economic loss. Often, awareness of the need for design or retrofit code revisions is raised immediately following extreme hazard events. Bridges that fail during extreme natural hazards usually have complicated failure causes, including environmental system collapses and massive structural malfunctions. Forensic investigations and performance analyses for bridges suffering such natural hazard events can be more challenging than those for bridges that fail in general service condition. General investigation guidelines or specific observational methods for such forensic investigations are not an easy task. Thus, actual performance of bridges under critical natural hazards is of great interest to practicing engineers and researchers.

This special section of the Journal of Performance of Constructed Facilities (JPCF) was proposed in an effort to introduce the current state-of-the-art for forensic investigations of bridge failures in recent extreme natural hazard events and to provide insights of performance analysis for the behavior of bridges under such extreme natural hazards. Fortunately, we were able to invite professional experts who had personally been involved in forensic investigation, failure analysis, and performance monitoring during recent extreme natural hazards including the 2011 Turkey Van Earthquake, the 2010–2011 New Zealand Christchurch Earthquakes, the 2011 Japan Tohoku Earthquake, the 2005 Hurricane Katrina in the United States, and the 2009 Typhoon Morakot that overran Taiwan. Case histories and performance data presented in these invited papers are invaluable to practicing engineers and researchers.

This special section includes case histories of bridge performance involving more than 20 bridges suffering from a variety of natural hazards such as strong ground motions, soil liquefaction, tsunami, storm surge, extreme winds, scour, and debris impact. Whether the bridge was damaged, failed, or luckily survived, such performance information and analysis results are instrumental to bridge design and retrofit against critical natural hazards, including great earthquakes and massive storms. Results of the forensic investigations and analyses have deterministic influences on upgrading guidelines of risk assessment, hazard mitigation, structural design, and retrofit.

Invited papers within this special section are generally divided into two major categories: bridge performance under seismic hazards and under storm hazards. The reported seismic hazards include strong ground motion in a recent Turkish earthquake and the Japan Tohoku Earthquake that caused severe damage to both highway and railroad bridges. These bridges were in locations that had undergone in-depth evaluations and design code revolutions in recent years. Very rare, yet devastating, failures caused by the tsunami accompanying the 2011 Japan Tohoku Earthquake are instructive not only to bridge engineers, but also to the general public. Studying these failures leads to a better understanding of the power of Mother Nature.

A research team from the University of Canterbury at Christchurch, New Zealand, introduces valuable performance data from bridges suffering from soil liquefaction and describes useful investigation practices. Such soil liquefaction causing bridge damage was broadly observed in previous large earthquakes, yet less detailed forensic investigation works were previously reported. Both the 2005 Hurricane Katrina and the 2009 Typhoon Morakot are recognized as critical storm events. Both resulted in substantial damage to bridges and a large number of bridge failures. Invited papers contributed by the Bridge Technology Office of the U.S. Federal Highway Administration (FHWA) and by Taiwanese research groups provide valuable forensic investigation and failure analysis techniques. Study efforts described in these papers are applicable internationally including advanced field investigation technologies and innovative computer simulations. Engineers rarely have such a valuable opportunity to conduct so many investigations. The resulting practice experience and investigation results are of great interest to bridge engineers and forensic engineering practitioners.

In the history of engineers fighting natural hazards, efficient safety warning is one of the greatest challenges. Development of smart sensors that can monitor bridge performance closely and punctually has been one of the top priorities of researchers in hazard mitigation. A research group from the National Taiwan University of Science and Technology presents a successful case history of recording bridge performance during Typhoon Morakot and verifying important performance characteristics of bridges under severe scouring. Such information is unique data that have never before been reported in an engineering journal.

Details of all forensic investigations, performance monitoring data interpretation, failure simulation, and design code verification are introduced in the included papers. Forensic investigations conducted on varying natural hazards and various performance analyses aiming to assess mechanisms of bridges damaged during recent major natural hazards are carefully presented. Typical failure patterns, generic failure causes, and behavior of bridges under strong ground motion, devastating tsunami, soil liquefaction, and torrential rain-induced multihazards are also thoroughly studied.

From this special section, readers may conclude that climate change and great earthquakes have been testing both the design and serviceability limits of bridges. Engineers are facing challenges because of the limited experience in mitigation of such extreme natural hazards, as well as in performance analyses of large-scale infrastructure failures. Improved forensic engineering knowledge in assessing the vulnerability and analyzing the performance of bridges under critical natural hazards is clearly needed. Information provided in this special section provides practical guidelines to engineers conducting investigations and analyses after such extreme natural hazard events. Moreover, the record of performance of bridges suffering from the natural hazards presented in this paper offers important information for future bridge design code revisions and improved risk analysis techniques for extreme natural hazards. We trust that instructive information presented in this section will be of great interest and assistance to engineers facing the challenges of designing against extreme natural hazards. Finally, we express deep appreciation to all the authors who have made enormous contributions to this special section and to the academic mentors who helped make connections to enable paper invitations, including Professor Kenji Ishihara at Chuo University and Director Myint Lwin at the FHWA Bridge Technology Office.

Dr. Wei F. Lee (Fig. 1) received his Ph.D. degree from the Department of Civil Engineering of the University of Washington in 2000. He is currently the Counselor and Task Force Executive for the Taoyuan Aerotropolis Project of the Taoyuan County Government, Taiwan. Before joining the Taoyuan County Government, Dr. Lee was a research professor at the National Taiwan University of Science and Technology. He is a supervisory board member of both the Taiwan Geotechnical Society and the Chinese Geosynthetics Association. He is also a member of several technical and board level committees of the International Society of Soil Mechanics and Geotechnical Engineering (ISSMGE). Dr. Lee is one of the pioneer researchers in Taiwan for maintenance engineering and forensic engineering of transportation infrastructure. Before joining the Taoyuan County Government, he directed more than 30 research projects per year. He has also been involved in organizing several international conferences and workshops, including the U.S.-Taiwan Bridge Workshop. During his professional career, Dr. Lee has been the principal investigator or project manager of more than 150 research and engineering projects, including subway constructions, seismic design and mitigation of foundations, transportation infrastructure management systems, and performance monitoring for bridges against aging and multihazards. Dr. Lee has authored more than 160 conference and journal papers. He is a member of the editorial advisory panel for the Institution of Civil Engineers (ICE) journal Forensic Engineering, an editorial review board member for the ASCE Journal of Performance of Constructed Facilities, and a manuscript reviewer for several other international journals.