The Local Mechanical Performance Of The Ultra-High Performance Light-Weight Composite Bridge Deck

Nowadays, many new built long-span bridges choose orthotropic steel decks as the deck system. However, in the engineering practice, it is proved that there are two major technical problems existing in orthotropic steel decks, i.e., steel deck fatigue cracking and conventional asphalt concrete pavement failure. To solve these two problems, our research team proposed an Ultra High-performance Light-weight Composite Bridge Deck structure, which was made by pouring ultra high performance concrete(UHPC) on the orthotropic steel decks equipped with stud shear connectors and dense steel mesh, and had a novachip on its surface. This new structure had excellent anti-fatigue performance, and it can not only be used for the renovation of old bridges, but also can be used for the construction of new bridges. This paper conducted preliminary investigations on the mechanical performance of Ultra High-performance Light-weight Composite Bridge Deck through model tests and numerical analysis, the main research works are as follows:Firstly, based on the design of the Dongting Lake Bridge's orthotropic steel deck several schemes were proposed for the Ultra High-performance Light-weight Composite Bridge Deck, including structures with close ribs and structures with open ribs. By using ANSYS software, finite-element models for those schemes were built and analyzed, and then the most suitable design of bridge system for Dongting Lake Bridge was chosen by comparing the displacements and stresses obtained from those finite-element models. The analysis results indicated that Ultra High-performance Light-weight Composite Bridge Deck has better mechanical performance, and compared with the initial design, it both had strengthened local stiffness and low level of structure stress; Moreover, among different schemes of Ultra High-performance Light-weight Composite Bridge Deck, compared with decks with close ribs, decks with open ribs had greatly reduced stress level on the crossbeam, and better anti-fatigue performance.Secondly, in order to study the static mechanical performance of Ultra High-performance Light-weight Composite Bridge Deck with close ribs, a full-scale test model was built based on based on the Dongting Lake Bridge. And the static loading tests were carried out both before and after pouring UHPC layer on the pure steel structure. The test results indicated that Ultra High-performance Light-weight Composite Bridge Deck greatly reduced the stress level of orthotropic steel deck's fatigue-sensitive parts, especially the steel deck whose stress level was reduced by 90%; however, it had little effect on the reduction of crossbeam's stress level.Thirdly, to study the static mechanical performance of Ultra High-performance Light-weight Composite Bridge Deck with open ribs, a full-scale test model was built based on based on the Dongting Lake Bridge. And the static loading tests were carried out both before and after pouring UHPC layer on the pure steel structure. The test results indicated that Ultra High-performance Light-weight Composite Bridge Deck greatly reduced the stress level of orthotropic steel deck's fatigue-sensitive parts; what's more, it also reduced the stress level of crossbeam by 60%, which was superior to that of the schemes with close ribs, meaning that the structure's anti-fatigue performance was improved.