Static Analysis Of Super High-toughness Concrete Composite Steel Box Girder Of Self-anchored Suspension Bridge

Self-anchored suspension bridges have received much attention in urban bridge design schemes due to their beautiful appearance,flexible structural selection,and anchor-free structure.Steel box girder orthogonal shaped steel bridge decks are widely used in self-anchored suspension bridges,but steel bridges Panels generally have two typical problems: fatigue cracking and pavement damage.Based on the solution of these two types of problems,this paper leads to the concept of ultra-high performance lightweight composite bridge deck structure from the material properties of ultra-high toughness concrete(STC),and summarizes the classification and analysis theory of lightweight composite bridge deck system.Based on a self-anchored suspension bridge-Xiangtan Zhaohua Xiangjiang Bridge,the static behavior of the self-anchored suspension bridge super-high-toughness concrete composite steel box beam is analyzed.The main research contents are as follows:(1)Establish A full bridge model and a steel box girder segment model of the self-anchored suspension bridge were established,and the overall stress of the steel box girder under the combination of standard values,STC pavement system and ordinary asphalt pavement system was analyzed.The analysis results show that the main influence of the STC pavement system is the stress on the upper flange of the steel box girder.And the STC pavement system makes the steel roof longitudinal The stress distribution is more uniform.(2)The finite element software ANSYS was used to establish the orthotropic steel bridge deck model,and the local stress characteristics of the suspension bridge steel box girder under the two pavement systems were compared and analyzed.The results show that the STC The roof plate,spherical flat steel longitudinal ribs and transverse ribs have different degrees of reduction in longitudinal stress,transverse bridge stress and equivalent stress.The STC pavement system has the largest stress drop on the steel roof,the maximum transverse tensile stress drop is 81.3%,and the transverse maximum compressive stress drop is 82.4%.The STC pavement system can effectively improve the local and overall stiffness of orthotropic steel bridge decks.The improvement is more obvious.(3)A comprehensive review of the fatigue theory of steel bridges was conducted.The fatigue model of orthotropic steel bridge decks was established by the finite element software ANSYS.The hot spot stress method was used to analyze the typical fatigue details of orthotropic steel bridge decks under two pavement systems.Stress amplitude,the results show that the fatigue detail of STC pavement system at the connection of roof and longitudinal ribs(1),(2)has the largest stress reduction amplitude,and the fatigue detail of the light composite bridge deck is lower than the corresponding fatigue level value and less than the constant amplitude fatigue limit value.(4)Fatigue performance sensitivity analysis is performed on the thick Ness of the STC layer,the thick Ness of the steel roof,the thick Ness of the transverse ribs,the thick Ness of the longitudinal ribs and the form of the longitudinal ribs of the lightweight composite bridge deck structure,so as to achieve the optimal design of the lightweight composite bridge deck.The results show that choosing the STC layer with appropriate thick Ness to improve the fatigue detail stress is more effective than changing the thick Ness of the steel box girder roof;the change of the thick Ness of the spherical flat steel longitudinal rib has the smallest effect on each fatigue detail;Fatigue performance is better than closed U-rib light combination bridge deck.