Construction Control Of Steel-concrete Composite Tied Arch Bridge And Its Performance Optimization

Tied arch bridges,a type of combination bridges,are widely used in traffic engineering.Construction of tied arch bridges is very complicated.To ensure the structural safety under construction and achievement of the design,accurate and effective construction control is the key point.With the increase of service time,tied arch bridges are likely to be faced with various diseases,some of which may even result in progressive collapse.Therefore,it is necessary to carry out preventive maintenance to reduce the risk of progressive collapse of tied arch bridges caused by local failure.Because of limitation of the materials adopted,long-span steel-concrete composite bridges have great weight and easily crack in the negative moment zone of concrete.Thus high performance materials should be introduced.This dissertation is based on Bayan Nur Xianfeng Bridge.Research on construction control of tied arch bridges was implemented by the adaptive control method and the construction simulation analysis.Several maintenance suggestions were given on the basis of bridge redundancy.And it was also studied the performance optimization of UHPC(Ultra-high Performance Concrete)Waffle deck panel to the static and dynamic performance of tied arch bridges in comparison with a flat concrete slab.The main contents of this dissertation are as follows.1.The construction simulation model was built using Midas Civil.Then the pre-camber of steel arches and the beam system was obtained as well as the fabrication length of suspenders and tie bars for reference during component processing.The tensile force of suspenders were acquired with the forward iteration method,and the suspender tension scheme was optimized considering the tension order so as to guide the suspender tension.Stress and displacement at critical positions during construction was calculated to evaluate the structural safety.Besides,the influence of construction error and environmental temperature on the completed bridge was quantitatively analysed,which replies the main design parameters.2.The results of construction simulation analysis were compared with the measured data.The former was consistent with the latter,and the completed bridge generally achieved the design intent,which prove that the construction control worked well.3.With the example of Xianfeng Bridge,the deterministic measures and the deterministic direct analysis method in NCHRP Reports were chosen to carry out the redundancy evaluation.The effect of different damage modes on capacity and functionality of the bridge structure was analyzed as well as the redundancy indices.It is advised for Xianfeng Bridge that the maintenance level be heightened,that the supervision of overloading be strengthened,and that suspenders be specially maintained.4.Based on Xianfeng Bridge,the static and dynamic performance of steel-concrete composite beam tied arch bridges with UHPC Waffle deck panel was compared to that with a flat concrete slab.The formulas to estimate the ultimate flexural capacity of a T beam with a wide flange and low rib were brought up,which considered the tensile strength of UHPC and the double reinforcement.And a simplifying method was raised to simulate Waffle deck panel with an equivalent anisotropic plate during overall bridge modeling.