There has been significant advancement in the design and development of cable-stayed bridges thus attracting interests in the field of civil engineering. Generally, they comprise of high-strength steel wires together with anchor systems. Unfortunately, these systems are susceptible to various forms of damages and failures due to causes such as fatigue damage, corrosions and vibration. Therefore, researchers have been looking for effective alternatives to improve their efficiency, functionality, and lifecycle.
This is specifically to reduce the need for frequent maintenance and cable replacements. In a recently published literature, carbon fiber reinforced polymer has been identified as a suitable replacement for steels owing to their efficient mechanical properties and high corrosion resistance.
This has seen the rapid increase in the use of carbon fiber reinforced polymers in the design and construction of cable-stayed bridges across the globe. However, their feasibility for long-span cable-stayed bridges is not certain. To this end, engineers assessed the stability and dynamic performance of long-span bridges through structural analysis and optimization procedures to minimize accidents related to failures. Also considering the increasing traffic volumes, understanding the fatigue behavior of the stayed cable systems is highly desirable in the design and evaluation of high-performance bridges.
To this note, Southeast University researchers: Dr. Bo Feng, Professor Xin Wang and Professor Zhishen Wu assessed the relationship between the fatigue life and safety factor in long-span cable-stayed bridges. In particular, they investigated the fatigue behavior of different types of materials i.e. carbon fiber reinforced polymers, basalt fiber reinforced polymers and steel. They aimed at improving the overall performance and life span of cable-stayed bridges through developing effective design and maintenance guidelines. Their work is currently published in the research journal, Composite Structures.
In brief, the research team cross-examined the fatigue cycles of the cables during design life. Secondly, the finite element analysis method was used to determine the stress amplitudes of the most unfavorable cable position. Next, the fatigue behavior of the cables was assessed based on the design stress and service life taking into account the sagging effects. Lastly, they evaluated the fatigue life of different cable made of different materials under varying safety factors by the equivalent transformation.
The authors observed that for long-span bridges going up to 2000m, fiber reinforced polymer cables exhibited longer fatigue life as compared to steel cables. The behavior of he sagging effects of the three materials: carbon fiber reinforced polymer, and basalt fiber reinforced polymer were reported to be significantly smaller than steel cable when the main-span increasing to 2000m. In addition, the fatigue life was noted to depend on the safety factors. For instance, carbon fiber reinforced polymer showed a higher increase in fatigue life with an increase in the safety factors as compared to basalt fiber reinforced polymer and steel in that order.
In summary, Professor Xin Wang and the research team investigated the fatigue life behavior of fiber reinforced polymers cables for the design of long-span cable-stayed bridges. To actualize their study, they accessed the 100-300 year fatigue life of the cables. In general, they came up with various safety factors for basalt fiber reinforced polymer, carbon fiber reinforced polymer and steel cables, as 3.27, 2.55 and 3.64 for 100-year fatigue life respectively. Altogether, the study provides vital information that will advance the design and maintenance of long-span cable-stayed bridges.
Feng, B., Wang, X., & Wu, Z. (2019). Fatigue life assessment of FRP cable for long-span cable-stayed bridge. Composite Structures, 210, 159-166.Go To Composite Structures