Research On Damping Performance Of Composite Box Girder With Corrugated Steel Webs

Box girder with corrugated steel webs, which uses corrugated steel webs instead of concrete webs, is a new composite structure. This type of structure has a great deal of advantages, such as light self-weight, excellent anti-seismic performance, high effective prestressing system, short construction period. The static properties of it get a lot of research results both domestic and overseas, but the research on dynamic properties is less. Damping is the parameter characterizing the energy dissipation in vibration of systems. Therefore, damping performance of composite box girder with corrugated steel webs is studied in this paper.Firstly, the equivalent damping ratio of composite box girder with corrugated steel webs using different section forms is solved through the relationship between complex frequency and hysteresis damping coefficient in this paper. In general anti-seismic analysis, damping ratio of such bridge is suggested to take 0.04.Based on stress related damping theory, the material damping ratio of reinforced concrete bending member is solved and compared to experimental results. It show that: the loss factor of reinforced concrete bending member increases non-linearly with stress level's increasing, and the higher the reinforcement ratio, the smaller the stress related damping ratio.Based on stress related damping theory, the damping ratio of composite box girder with corrugated steel webs under different working conditions is solved by energy method, and the impact of different structural parameters on it are discussed. The analysis results show that: damping ratio is recommended to take 0.3% when the composite box girder with corrugated steel webs in a low stress state; the thicker the corrugated steel plate, the larger the strength of concrete, and the decreasing of corrugated steel folding angle, the damping ratio decreases.Based on standard response spectrum of seismic code, the response spectrum revised from the equivalent damping ratio calculated by complex frequency and from the damping ratio iteratively calculated using the stress related theory; the seismic response of composite box girder with corrugated steel webs is calculated using different response spectrum. The comparative analysis shows that the results calculated from the response spectrum revised from the damping ratio iteratively calculated by using the stress related theory tends to safety and the damping ratio can reflect the energy consumption of structures in different stress level.