Crews from C.W. Matthews Contracting Co., Marietta, Ga., are removing debris from an Interstate 85 bridge in Atlanta that collapsed during a March 30 rush-hour fire. No injuries were reported, but the incident forced an extended closure of the highway section. Investigators say the fire was intentionally set inside a fenced Georgia Dept. of Transportation surplus equipment storage area beneath the structure, and it intensified after spreading to a stockpile of polyethylene and fiberglass conduit. Flames and high temperatures subsequently compromised the bridge’s structural integrity. Authorities have charged one individual with arson and first-degree criminal damage to property, while two others were cited for criminal trespass.
On March 31, the Federal Highway Administration released $10 million in emergency relief funds to initiate site cleanup and bridge replacement work. GDOT engineers already have completed designs to replace about 700 ft of roadway and supports, while fabrication of 61 beams and other elements is underway. According to the agency, the use of 24-hour accelerated curing concrete and, where possible, reinforcement of surviving supports will help C.W. Matthews to expedite construction, with an eye toward reopening I-85 in mid-June. GDOT has not announced a cost for the emergency construction contract, which the agency says will include performance incentives and penalties.
Because it can moderate the damaging effects of earthquakes, base-isolation is a technique used primarily in seismically active regions. ENR takes a look at some of the largest applications of base-isolation technologies in the world.