UHPFRC Strengthening Method for Existing Bridges

摘要

Ultra-high performance fiber reinforced concrete (UHPFRC) is an optimal selection for bridge strengtheningrnprojects, because of the distinguished material properties like high compressive and tensile strengths,rnductility, durability, compactness, and low creep. This paper focuses on a strengthening method for bothrnsteel bridges and concrete bridges using UHPFRC. For steel bridges, UHPFRC overlay is proposed tornstrengthen orthotropic steel bridge decks. The UHPFRC layer acts in composite action with the steel deckrnplate by applying an epoxy resin glue at the interface of the two materials, which is verified to be anrneffective way to improve structural rigidity by means of experiments. For concrete bridges, UHPFRC layer isrncast on the top surface of the deck slab. This technology has already been applied to several bridges asrnwaterproofing layer and to effectively increase the ultimate resistance of the deck slab of bridges. Besides,rnfor the bottom flange of concrete girders in the tensile state, UHPFRC and steel composite strengtheningrnmethod is proposed. Studs are anchored in the bottom flange of the original concrete girder and a Ushapedrnsteel plate with studs is arranged such as to cover the bottom flange and part of the web. This Ushapedrnsteel plate also serves as a formwork for UHPFRC casting between original concrete girder and steelrnplate, such that an overall cross section is formed and the UHPFRC-steel plate strengthening part work inrncomposite action with the original girder. A concrete bridge box girder section is selected as a case study tornvalidate the UHPFRC strengthening method for both steel and concrete bridges with the objective tornimprove structural performance effectively.