Research On Influence Of Hydration Heat Of Concrete In Pipe Of Long-span Concrete-Filled Steel Tube Arch Bridge

Concrete-filled steel tube arch bridges have developed rapidly in recent decades.Because of their high bearing capacity,rapid construction,and adaptation to more complex terrain,they can be used in large-scale infrastructure construction.There are still problems to be studied in the concrete-filled steel tube arch bridge,and the influence of the heat of hydration on the concrete in the tube is one of them.Therefore,it is necessary to perform a refined analysis of the heat of hydration on the concretefilled steel tube arch bridge.On the one hand,it can enhance the understanding of the redistribution of internal forces in the structure,and on the other hand,it can improve the accuracy between the actual internal forces of the structure and the design internal forces.Based on the Hejiang Yangtze River Highway Bridge,this paper studies the influence of hydration heat in the pipe of a large-span concrete-filled steel tube arch bridge.Firstly,it focuses on the analysis of the distribution and change law of the hydration heat temperature field and temperature stress of the concrete-filled steel tube arch ribs,and explores the most suitable pouring time of the arch-rib concrete.Secondly,the pouring sequence interval time of the long-span concrete-filled steel tube arch bridge is discussed.Finally,the concrete hydration heat is discussed.The arch ribs under the influence are analyzed.The main research contents are as follows:(1)Based on the basic theories of heat conduction and thermal stress,the finite element method is used to study the temperature field and temperature stress of the hydration heat of concrete-filled steel tube,and the assumption of the temperature field of concrete-filled steel tube is proposed.(2)Analyze and select the simulation parameters of the concrete-filled steel tube model,establish a solid model of the concrete-filled steel tube arch rib,conduct a refined analysis of the temperature field and temperature stress of the hydration heat of the arch rib section,and determine the temperature field and stress field distribution characteristics and changing laws.Exploring the changing trend of different sensitivity parameters on the temperature field of the arch rib section,the results show that the thermal conductivity of concrete and the diameter of the steel pipe have a significant effect on the temperature field;the thickness of the steel pipe wall has a small effect on the temperature field and can be ignored.(3)The issue of concrete pouring time for concrete-filled steel tube arch ribs was explored,and the results showed that the pouring time of concrete arch ribs is suitable for pouring in a higher temperature climate of about 30℃.According to the influence of the temperature difference between day and night on the cross-sectional temperature field,it is concluded that the time of arch rib pouring should be considered in the higher temperature period of the day when the temperature peak occurs.(4)From the perspective of considering the influence of the heat of hydration of concrete,discuss the force change of the concrete-filled steel tube arch bridge under the action of the heat of hydration,and explore the influence of the interval time of the two arch rib pouring sequence on the arch rib line type according to the actual engineering problems.The most suitable interval time for the single arch rib pouring is determined,and the stress and deformation of the arch rib are collected during the pouring process,and the actual collected data is compared and analyzed with the calculated data.(5)Discuss the influence of concrete hydration heat on the vacancy of arch ribs.The analysis results show that the influence of surface hydration heat in the radial direction is negligible,and slippage will occur in the longitudinal direction.Ultrasonic testing equipment is used to detect and calculate the void of the concrete in the pipe after the actual arch rib is poured on site.