Finite Element Analysis Of Static Performance Of Steel-UHPC Lightweight Composite Girder

Although the traditional steel-concrete composite beam is lighter weight compared with the concrete beam, and has considerable superiority on economy compared with steel beams, there are heavy self-weight and concrete beam deck cracking problems existing in the traditional steel-concrete composite beam.To solve these two problems, our research team proposed a steel-UHPC lightweight composite beam structure which used the waffle UHPC beam deck to replace ordinary concrete slab and had a novachip on its surface.This paper conducted preliminary investigations on the technical and economic performance and effects of the car loads of the Steel-UHPC Lightweight Composite Beam Deck through numerical analysis. The main research work is as follows:Firstly, based on the design of the Shengtian Bridge’s steel-concrete composite beam, the steel-UHPC lightweight composite beam structure was proposed. A no transverse surface tension joint scheme and a one-way flexural scheme of the steel-UHPC lightweight composite beam structure were also proposed, in order to ensure the integrity of the composite beam.The technical performance comparison of the steel-UHPC light composite beam and the traditional steel-concrete composite beam, and the economic performance comparison with other three kinds of deck structures were carried out.The analysis results showed that the steel-UHPC light composite beam can significantly reduce the self-weight and extend the range of the economic application span of the composite beam. The crack-resisting ability of the steel-UHPC light composite beam was superior to the traditional steel-concrete composite beam. The whole life cost of the steel-UHPC lightweight composite beam is only slightly higher than that of the traditional steel-concrete composite beam.Secondly, because the UHPC waffle deck panel is thin, in order to study the effects of the car loads, three different methods were used to capture the stresses in the UHPC waffle deck, i.e. the stress superposition method, the precise overall bridge FE method and mixed FE method based on the Dongting Lake Bridge. The FE analysis was focused on the tensile stress and compressive stress in the concrete deck at the most unfavorable load positions.The analysis shows that: The analysis results obtained from the mixed FE method are quite close to the results derived from the precise overall bridge FE method and the stress superposition method leads to a safe result.The maximum tensile stress of UHPC deck is lower than the nominal tensile stress of UHPC that have a maximum crack width of 0.05 mm and the maximum compressive stress is much less than the compressive strength of UHPC under vehicle load.Thus, the UHPC deck is in the line elastic stress state and can meet the design requirements under the most unfavorable vehicle loading conditions.Thirdly, in order to verify the safety of the steel-UHPC lightweight composite beam, the static analysis of the Shengtian Bridge was carried out.The analysis shows that: Under the frequent combination of normal use limit state, the longitudinal tensile stress of the UHPC deck is lower than the nominal tensile stress of UHPC that have a maximum crack width of 0.05 mm. The UHPC deck can meet the requirements of the standards, and the steel-UHPC lightweight composite beam can effectively solve the problem of easy cracking of composite beam bridge decks.