Preservation of Historic Thin-Shell Concrete Structures

Thin-shell concrete structures were developed in the mid-twentieth century in response to the need for economy in large-span structures and in response to the design and aesthetic program of the modern movement in architecture. Although of European invention, these structures were widely employed in the United States for industrial and military structures, stadiums, auditoriums, and shopping centers. Because of changing building economics and changing tastes, significant thin-shell concrete structures have not been built in the United States since the mid-1970s. In spite of their relatively recent construction, many surviving thin-shell structures can be considered as historic according to the Criteria for Eligibility for the National Register of Historic Places. However, a lack of awareness of the significance of these structures has caused the recent removal of two important thin-shell concrete structures, the New Orleans Convention Center and "The Paraboloid," an entrance canopy for the May D&F store in downtown Denver. Others, such as Seattle's Kingdome Stadium, are clearly threatened. In this paper, we examine the historical and social context of thin-shell concrete structures, discuss the threats to the preservation of these structures, and outline a strategy of professional and public awareness and strategic repair.