The smooth-walled box structure system described in this paper represents a new approach to the problem of providing efficient transport of water beneath ground cover with limited crown clearances. The smooth walls of these structures provide significantly increased hydraulic efficiency over that achieved by current conventional corrugated metal box culverts. This hydraulic efficiency offsets the decreased structura efficiency (decreased flexural capacity) of the composite smooth plate/rib section and permits the use of a significantly smaller smooth-walled box structure cross-sectional area to transport the same maximum design flow volume as would be transported by a significantly larger corrugated box culvert cross-sectional area. Use of this smooth-walled box structure, in turn, minimizes overall structure size and cost, requires smaller clearances for installation under shallow cover constraints, and minimizes the excavation and backfill volumes required for installation. A summary of the studiesinvolved in the analysis and preliminary design and testing of thisnew type of box culvert system is presented in this paper. Includedare an overview of the design procedures used to develop the new smooth-walled box structural system, a summary of the scale-model hydraulic testing program performed to evaluate hydraulic performance, asummary of the results of full-scale laboratory structural tests ofthe various new box culvert system components, and a discussion of finite element analyses performed to evaluate the proposed new culvert system. In addition, a full-scale prototype structure was constructed, backfilled, and then subjected to repeated cycles of hs-20 design loading. The results of this full-scale prototype test, as well as finite element analyses of this test, are also presented and discussed. This paper appears in transportation research record no. 1231, Analysis, design, and behavior of underground culverts.
Abstract