Stability Analysis on Single-column Steel Cable Pylon during Construction
In order to find out and verify the structural stability and ultimate bearing capacity performance of the single-column steel pylon of cable-stayed bridge during construction,and to guide the design and construction,taking the steel cable pylon of Shangba Jiajiang Bridge as the engineering background,based on the finite element method,the study is conducted on the elastic and elastic-plastic stability performance of the main bridge during construction.The structural overall stability is analyzed by using a frame model,and the structural local stability is analyzed and verified by using a multi-scale model.The free-standing pylon working condition,maximum double cantilever working condition and maximum single cantilever working condition are analyzed.The main instability modes of the structure are obtained through elastic stability analysis,the continuous formation process of the structural plastic hinge is obtained through elastic-plastic stability analysis,and the structural ultimate bearing capacity and failure location are clarified.The result shows that(1)dead load is the main factor determining the stability coefficient by comparing the influence of dead load and wind load on the stability of single-column steel pylon,and wind load has a small impact on the elastic stability coefficient of the steel pylon during the construction stage,but has a large impact on the elastic-plastic stability coefficient;(2)with the process of construction,the overall elastic stability and elastic-plastic stability of structure gradually decrease,with the elastic stability coefficient decreasing from 18.5 to 16.3,and the elastic-plastic stability coefficient decreasing from 3.03 to 2.57;(3)the final failure mode of the single-column steel pylon is that the large area of the middle and lower pylon region reaches the yield strength,forming a plastic hinge,the bearing capacity of the pylon rapidly decreases,the structure loses its bearing capacity,and the possible failure locations are probably the middle and lower pylon region;(4)the minimum elastic stability coefficient of the single-column steel pylon in the construction stage is 16.34,and the minimum elastic-plastic stability coefficient is 2.57,both of which meet the stability requirements.
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