Research on the Impact Effect of the Breakage of Hangers in Suspension Footbridges
The breakage of hangers in suspension footbridges not only causes local collapse in bridge deck,but also leads to continuous breakage in hangers due to excessive stress redistribution in remaining components.The structural dynamic response of a suspension footbridge was analyzed using numerical simulation methods under the breakage of a single hanger and two adjacent hangers.The impact effect of the breakage of hangers was comprehensively evaluated through static redistribution factor(SRF),dynamic redistribution factor(DRF),oscillation factor(OF),and dynamic amplification factor(DAF).The results show that after a single hanger fractures suddenly,the static and dynamic redistribution degree of adjacent remainder hangers on the same side and the longitudinal girder under the broken hanger is obvious,but the impact on the main cable and hanger on the opposite side is relatively small;For the remaining hangers and the longitudinal girder under the broken hangers,the breakage of two adjacent hangers on the same side has a greater impact than that of the two adja-cent hangers on the same side;Except for the edge hanger and mid-span hanger,the SRF and DRF of all remai-ning hangers are around 50%and 100%,respectively;The DAF values of the remaining hangers near the mid-span area are all around 2.0,but the DAF of the edge hanger is increased by about 25%compared to that of the mid-span area.Using a DAF of 2.0 for the edge hanger is not safe.The DAF values of the bending moment of the longitudinal girder below the broken single hanger are all between 1.20 and 1.40.
bridgesuspension footbridgebreakage of hangerdynamic responseimpact effect
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