Abstract
In this paper, the stress-related damping ratio formula of box girder with corrugated steel webs is introduced. Using response spectrum method, an iterative algorithm is proposed to calculate the seismic response and the stress-related damping ratio under different seismic intensities. Based on a simply supported composite box girder bridge with corrugated steel webs, the stress-related damping ratios are calculated under different seismic intensities through iteration. The analysis and comparison show that the stress-related damping ratio increased with the seismic intensity, which is smaller than 0.05 under the lower seismic fortification intensity, and larger than 0.05 under the higher seismic intensity. Different damping ratios should be considered under different seismic intensities for the seismic response analysis of the bridge.
Highlights
Box girder with corrugated steel webs represents a new innovative system which has emerged in the past decade for short and medium span bridge
The new system usually combines the usage of corrugated steel plates as webs and reinforced/prestressed concrete slabs as flanges for plate or box girders [1]. This bridge type has been widely applied since the French built the first box girder bridge with corrugated steel webs in 1986 [2]
Liu Baodong proposed that appropriately adding the diaphragm can improve the torsional behavior of corrugated steel webs through comparing the natural frequency of different diaphragm schemes [7]
Summary
Box girder with corrugated steel webs represents a new innovative system which has emerged in the past decade for short and medium span bridge. Hart identified the first three modes of damping ratio according to the earthquake records data of 12 high-rise buildings [11] He found that the damping ratio of the structure increases when the ground motion got stronger. Lagomarsino collected damping ratio measured data of 182 buildings, and found that the damping ratio value relates to the natural frequency of structure[13]. Considering the structural characteristic of the box girder with corrugated steel webs, this paper introduces a stress-related damping ratio formula based on the loss energy per unit volume of metal material [24] and reinforced concrete material [25]. An iterative algorithm is proposed and the damping ratios under different seismic intensities are iteratively calculated based on a real supported composite box girder bridge with corrugated steel webs. The seismic responses with stressrelated damping ratio and constant damping ratio are compared using response spectrum method
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