Articles

Design and Detailing of Nebraska's First UHPC Ribbed Slab Decked I-Beam Bridges

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Abstract

The state of Nebraska has embarked on an ambitious program to design a series of bridges using ultra-high-performance concrete. Several bridges are under various stages of design, with the first one scheduled for release to bidders in August of 2023. The design is based on previously completed research by the University of Nebraska to create a cost effective UHPC mix. The non-proprietary mix only costs a fraction of prebagged proprietary mixes. It achieves very high tensile properties and adequately high compressive strength. It also achieves excellent durability. Using this mix along with a highly optimized decked I beam cross section achieves a cost competitive UHPC superstructure system that also features rapid construction and highly durable deck. This presentation covers the features of design of four bridges being designed for NDOT. The first bridge is the Belvidere North Bridge, in Belvidere, Nebraska. The other three are overpasses over I-480 in Omaha, Nebraska. The Belvidere North Bridge is the first one to be designed with this system. It will be the focus of the presentation. It consists of three spans, 75-85-75 ft. It is 42 ft-8 in. wide. Each span consists of four 54 in. deep by 10 ft-2 in. wide decked I-beams with 8 in. wide UHPC closure pours. The I-480 bridges vary in length and width. Typically, they are two-span, 250 ft long bridges. The presentation covers design and detailing in the longitudinal direction and the transverse direction. It shows analysis for the closure pours to meet two conditions: permanent net compression across the joint between precast and CIP components using transverse post-tensioning, and full strength resistance with rebars embedded in the CIP joint. Design and detailing over the piers for continuity due to superimposed dead loads and live load will be discussed. Design and detailing of an open railing system for crash loading will be covered. Resistance of the top flange ribs to this extreme loading will be shown to be satisfactory without need for converting the overhang in this area to a solid slab. Two types of longitudinal prestressing will be covered. The first type is a segmental match-cast post-tensioning system. The second type is an innovative incrementally cast pretensioned system. Both systems are motivated by the desire to accommodate precasters in the US where mixers are limited to about 2-3 cubic yards per batch and where production of a full span product involves higher risk than production of short segments.

Keywords: UHPC decked I beam, forming system, accelerated bridge construction, segmental construction, standardized girders shape

How to Cite:

Stubbe, A., Sevenker, A., Abo El-Khier, M., Jaber, F. & Zillig, K., (2023) “Design and Detailing of Nebraska's First UHPC Ribbed Slab Decked I-Beam Bridges”, International Interactive Symposium on Ultra-High Performance Concrete 3(1): 38. doi: https://doi.org/10.21838/uhpc.16663

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