TPT November 2017

G LOBA L MARKE T P L AC E

G LOBA L MARKE T P L AC E

Those sensors are expected to last at least a decade, Mr Maroney said. Divers will also use ultrasonic waves to monitor corrosion on the outside of the piles that extend from the base of bridge to the seafloor. › But the incident of the anchor rods in the tower seems to have given way to other questions about steel integrity. Mr Maroney said that the researcher who voiced the current concerns, Justin Ocel in the FHA’s structural steel research programme, did not express any anxiety about the safety of the Bay Bridge. A peer review panel is to study the results of tests on steel plates in service on the bridge, and these are expected to be made public before the end of the year. According to the Mercury News on 30 August, Mr Ocel declined to comment, saying his research was not yet complete. Elsewhere in steel . . . › Clarksons Platou analyst Lee McMillan estimated that some 200,000 automobiles and many appliances would be junked because of Hurricane Harvey-related flooding and that tighter scrap supplies in the Houston region could help boost steel prices. “There’s some incremental steel demand that will come of this,” he told Bloomberg First Word (30 August). “We just don’t know how much.” KeyBanc’s Philip Gibbs also envisioned a price rise, as Houston handles 30 to 35 per cent of US steel imports – creating a “relative tactical positive” for steel companies. US Steel, AK Steel, Nucor and Steel Dynamics were among the producers whose stock prices rose on speculation that flooded scrapyards in Houston could pinch feedstock supplies. › The Johannesburg-based daily Business Day reported (4 September) that Liberty House said it will pump A$1.26bn (US$995mn) into steelmaking capacity in Australia to meet the demands of a decade-long infrastructure boom in the country. The announcement came months after the British firm acquired an Australian steelworks that was in voluntary administration and billions of dollars in debt. Liberty’s executive chairman, Sanjeev Gupta, said a 100-day review would produce a plan to transform the Whyalla plant in South Australia, including providing for its power needs by harnessing waste gases and investing in pumped hydro and large-scale solar energy. Mr Gupta told the Australian Financial Review of plans for raising the steel plant’s capacity to 1.5 million metric tons. His broader ambition is to increase output from the electric arc furnaces and rolling mills on the east coast to accommodate an “immense” ten-year pipeline of new projects in Australia.

Steel In the finishing-touches phase of the new Bay Bridge in California, more questions about steel integrity and corrosion Nearly four years after the Oakland-San Francisco Bay Bridge opened to motorists, California Department of Transportation (Caltrans) engineers have declared the final structural repairs complete. The work involved the replacement of faulty grouting inside the bridge’s tower and brought to a close a saga of construction delays and complications that imposed a ten-year delay and additional costs of more than $5bn. But apparently the span used by some 270,000 motorists daily is not entirely free of steel and corrosion issues. As reported by Erin Baldassari, who covers transportation for the Mercury News (San Jose, California), an as-yet unpublished report by the Federal Highway Administration (FHA) found that the steel supporting that bridge traffic is weaker than required by Caltrans. (“Structural Work on Bay Bridge Complete, but Questions Remain about Subpar Steel,” 30 August) Brian Maroney, the chief engineer for Caltrans, rejected the suggestion that the agency had accepted substandard product and that the steel was not performing as it should. He told the Mercury News that some variation in steel strength – deriving from the thickness of the metal and the effect of welding on its properties – was not unusual. “It’s to be expected,” he said. “The inside may have a lower yield strength, but it’s just as strong in ultimate strength.” Summarising the history of the $6.5bn span since it started carrying passengers in September 2013, the Mercury News noted that the troubles started a few months after engineers tightened 96 steel bolts intended to stabilise the bridge during an earthquake. Finding 32 rods to be brittle and cracked, Caltrans put a fix in place; but further investigation revealed that bad grouting had allowed water to seep into the tower’s foundation, putting the more than 400 anchor rods at risk of corrosion. “It didn’t help that the threads on a few of the rods were stripped, further weakening them,” Ms Baldassari wrote. › Caltrans removed the faulty grouting and restored it. At the same time, Mr Maroney said, engineers tested every accessible rod and have given assurances that the rods can withstand the force of the largest earthquake likely to occur over a 1,500-year period. The agency will continue to monitor for corrosion in the tower’s anchor rods with 18 sensors embedded in the grout.

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NOVEMBER 2017