By now, more than 12,000 people have watched this extraordinary time- lapse video of a C.D. Smith Construction team easing an 85-foot-high wall 35 feet outward to expand Milwaukee’s Grand Theater and trans- form it into the new Milwaukee Symphony Center. What few people may have thought about—and what GZA is proud to have played a key behind-the-scenes role successfully completing—is what needed to be done to ensure the soil could support the 1.25-mil- lion-pound weight of the historic wall being moved, including the precise installation of more than 45 truckloads of gravel to strengthen the soft, silty soils at the project location. GZA assists with move of million-pound wall for Milwaukee Symphony Orchestra’s new home By John Siwula Photo: C.D. Smith Construction, Inc.
The Grand Theater is cherished in Milwaukee as one of the city’s most iconic buildings and an architectural gem of Wisconsin Avenue. As the Milwaukee Symphony Orchestra began developing its $90 million plan to convert the theater into a new 1,750-seat performance space, there was never a question that the historic 1932 steel-frame wall, with its cream city brick infill and terracotta cladding, would be preserved and restored rather than demolished. Yet doing so would require some careful design. First, there was the wall move structure itself: Any system put in place needed to support the rails and jacks used to roll the wall outward, the 100 construc- tion workers supervising the move, and the 625-ton weight of the wall itself. Secondly, the wall move had to be designed to avoid any impact on an existing, 70-year-old underground steam-heat tunnel, and had to be coordinated with eight separate utility relocations within Second Street. Furthermore, the structural engineers’ specifications were that the move could allow for no more than ½ inch of settlement. Finally, the earth the building rested on presented its own challenges. The Grand Theater site is underlain with variable strength fill followed by compressible estuarine deposits which are subsequently underlain by high strength glacial till soil. The near surface estuarine soils con- sisted of very soft, highly organic, fine-grained soils (peat and OL- and OH-type soils) ranging from about 1 to 2 feet thick. Below the thin upper organic layer, soils were generally comprised of interbedded,
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february 2020
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