Many modern bridges use orthotropic steel bridge decks (OSBD), the decks being the surface sections of the bridge. OSBDs were designed to be lightweight and economical. However, this design has shown increasing issues with pavement cracking and fatigue damage at the welds that connect the bridge deck to the bridge superstructure. Fatigue damage is damage that accrues over time with use.
To ameliorate these problems, a new bridge deck was designed. The composite bridge deck system (CBD) added a layer of concrete to decrease the probability of damage due to fatigue. More recently the use of high-performance materials, such as ultra-high-performance concrete (UHPC) and engineering cementitious composites (ECC), have been incorporated into the CBD design.
Chinese scientists recently reviewed current research on the performance and durability of these two types of bridge deck designs and the effect of incorporating the new high-performance materials into the design of the newer CBD.
"Both new and traditional bridge deck systems possess distinct advantages and disadvantages, indicating their suitability for various application scenarios. A comprehensive review of these bridge deck systems can provide scholars and engineers with a deeper understanding and facilitate their effective application" said Jingzhong Tong, a researcher at the Institute of Advanced Engineering Structures.
Their review was published on April 29 in Intelligent Construction.
The researchers reviewed studies on the traditional orthotropic steel bridge deck systems, along with the newer composite bridge deck system which used one of three different materials: the original steel- concrete, and two high-performance materials, steel- UHPC and steel-ECC. UHPC and ECC are cementitious composites with properties that are very useful in bridges.
UHPC has ultra-high compressive strength allowing for the use of thinner slabs with greater bending strength and greater stiffness than regular concrete. It is therefore easier to build with and does a better job under stress. ECC is very tough and highly resistant to cracking.
The studies they reviewed used different measures of bridge deck fitness. Examples of the types of measurements used in the papers included a bridge deck's flexural behaviour, which is how the materials and design of the bridge deck react to loads that may cause bending, the fatigue behavior of critical welds on the bridge deck and the durability of the pavements, among many other factors.
The review found that fatigue performance was the greatest issue in the OSBD, and that the CBD design had comparatively greater fatigue resistance and sectional stiffness, which would be useful in long span bridges. When the UHPC was used in the CBD design instead of the steel-concrete, it increased the bridge decks' flexural performance. ECC use improved the bridge decks' crack resistance.
"The integration of these advanced cementitious composites into bridge deck systems significantly enhances their mechanical properties and durability, thereby mitigating the high maintenance costs associated with repetitive damage," said Yunlong Chen, the paper's first author and a scientist at Zhejiang University.
Overall, on looking at the research that they had reviewed the scientists felt that "for critical infrastructure where frequent maintenance is impractical, the implementation of new bridge decks utilizing cementitious composites is highly recommended due to their superior durability," said Qinghua Li, a researcher at Zhejiang University. The cementitious composites are more expensive initially, but with the increased durability of the resulting bridge decks and their lower maintenance costs over the life span of the bridge, this would result in a lower cost in the longer term.
When asked what comes next Chen said "the next step is to reduce the cost of cementitious composites, thereby expanding their range of applications. Subsequently, the design method for the new bridge deck system utilizing cementitious composites could be validated through more practical engineering applications. The ultimate goal is to develop an ideal bridge deck that achieves affordability, long service life, lightweight construction, and convenience in installation."
Other Contributors include Shilang Xu from the Institute of Advanced Engineering Structures, Zhejiang University, Hangzhou, China and Luming Shen of the School of Civil Engineering, The University of Sydney, New South Wales, Australia.
This study was funded by Zhejiang Provincial Natural Science Foundation of China, the National Natural Science Foundation of China, and the ZJU-USyd Ignition Grants.
About Journal of Intelligent Construction
Journal of Intelligent Construction (JIC), sponsored by Tsinghua University and the China National Committee on Large Dams, published by Tsinghua University Press (TUP) and exclusively available via SciOpen, is a peer-reviewed journal for publishing original research papers, case studies, reviews and comments regarding the use of novel technologies in all domains of civil engineering, e.g., hydraulic engineering, structural engineering, geotechnical engineering, transportation, and construction management. The journal focuses on the application of advanced theories, methodologies, and tools, such as machine learning, sensors, robotics, 5G, the Internet of Things, artificial intelligence, building information modelling, and computational methods, etc., in all stages of the construction life cycle, which makes the process more intelligent and efficient. The journal also covers other essential areas of civil engineering, e.g., planning and design, operation and maintenance, and disaster mitigation.
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