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Editorial

Khaled M. Mahmoud
2009 Bridge Structures  
The shocking collapse of the I-35W Bridge over the Mississippi River in Minneapolis, Minnesota, USA, on August 1, 2007, served another wakeup call to the bridge engineering community. The collapse took place during rush hour plunging dozens of cars and their occupants into the river. Each bridge failure, since the Tacoma Narrows Bridge disaster in 1940, has prompted radical changes in the standards of design and construction. However, a paradigm shift is necessary in the inspection, monitoring
more » ... ection, monitoring and preventive maintenance practices to restore the public's confidence in the safety of bridges. Issues of bridge safety and reliability are shared by bridge engineers from different countries. This special issue of Bridge Structures presents a number of selected papers that were presented at the Fifth New York City Bridge Conference, held on August 17-18, 2009. These papers provide invaluable contributions to the state-of-the-art in bridge engineering. The issue leads off with off with a paper by Hopwood et al. "Addressing SCC-susceptible ASTM A514 steel on the I-275 twin bridges over the Ohio River". Failure analyses of cracked splice plates made from ASTM A514 quenched and tempered steel revealed that the steel was inadequately tempered resulting in excessively hardened, brittle defective steel. Consequently, this steel was also susceptible to stress corrosion cracking/hydrogen stress cracking. The I-275 twin bridges contained large quantities of A514 steel that needed testing to identify any remaining defective steel. A test plan was developed that incorporated hardness testing to discriminate between acceptable and the defective A514 steels. The plan incorporated the use of the ultrasonic contact impedance and impact hardness test methods. Field hardness testing was conducted over a 10-week period beginning in October 2008. During the testing, two additional cracked splice plates were discovered that contained defective A514 steel. The paper presents details of the testing plan to identify defective A514 steel plates on the two bridges. The structural response of a steel orthotropic bridge deck is characterized by the complex interaction between its components. In the case of ribs passing continuously through cutouts in the floor beam web, the floor beam exhibits a Vierendeel type truss Bridge Structures
doi:10.1080/15732480903183223 fatcat:oqnf625cgbct3ijdfbk2ftbe5m