Concrete Products

JUL 2012

Concrete Products covers the issues that attract producers of ready mixed and manufactured concrete focusing on equipment and material technology, market development and management topics.

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FEATURE CONCRETE TECHNOLOGY to handle not so much the [super girders'] length, but the weight," he adds. All told, an 18-wheel trailer connected to the fifth- wheel cradled the front of the girder, a rear, driveable, 32-wheel trailer maneuvering the back. A driver manned the cockpit of the rear trailer, which looked akin to a vehicle out of a Mad Max movie. V. Van Dyke used a pair of identically spec'd Kenworth T800s with 550-hp en- gines driven through 18-speed transmis- sions. Heavy duty is the name of the game with one pusher and two drive axles, each rated at 46,000 lbs., plus 20,000 lb.-rated front axles. "With minimal hills to navigate and basically a straight shot on Highway 99 from Tacoma to Seattle, the T800 had plenty of power to pull the load," says Bates. "We were fortunate that the only corner we needed to navigate was near the Port of Tacoma where we picked up the girders. The tricky part was running the 16- foot tall load between traffic signals. There wasn't a lot of room for error and there was a lot of pressure for the rear driver to nav- igate a straight line." Continued on page 66 To ramp up for the Alaskan Way Replacement southern mile girder shipments, V. Van Dyke added front trail- ers and steerable rear trailers to its fleet, anchored by 18 Kenworth T800 heavy haulers. Equipped with hy- draulically actuated axles, expandable to 16 ft. wide, the new trailers exhibit stiffness negating load rollover and combine for 270,000 lbs. of legal hauling capacity—14,500 lbs. above the 205-ft. girders' weight. Con- crete Tech engineers have helped optimize delivery contracts by updating in-house algorithms factoring new or existing Van Dyke trailers' rotational stiffness. Shipping stresses, coupled with stability and lifting factors, compelled WSDOT designers to run eight temporary pretensioned strands in the longest WF100G beams. The strands are bonded for 10 ft. from each end, running through debonding sleeves the remainder of the girders. Lifting hardware is set at 19 ft. from each end. Support locations for hauling were at 25 ft. from one end and 30 ft. from the other. To mitigate traffic concerns, a police escort tripped stoplights so Van Dyke drivers could pass inter- sections unencumbered. The girders were moved at dusk with loads leaving Tacoma between 7 p.m. and 8 p.m. "Still that's pretty early and there was traffic out there, but we needed to get the girders to the job site so they could start putting those in place at night, when they didn't tie up much traffic," says Van Dyke's Cliff Bates. WWW.CONCRETEPRODUCTS.COM JULY 2012 | 65

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