Analysis Of Temperature Effect And Closure Technology Of Rigid Frame-Continuous Composite Beam Bridge In Cold Region

China has a vast territory,so the climate varies widely.While the climate in the cold regions is variable and diurnal range is obviously,resulting in a unique temperature field distribution of the box girder in the region.It is obviously unreasonable to adopt a single temperature gradient model in China’s specifications.Temperature effect is one of the main reasons for cracking of concrete box girder bridge.And the temperature crack seriously jeopardizes the safety and durability of the bridge structure.Therefore,it is very significant that the analysis of the temperature distribution and temperature effect of the rigid frame-continuous composite beam bridge,in which the temperature gradient curve of the concrete box girder which is more in line with the actual situation of the cold region.The rigid frame-continuous composite beam bridge has many closure section and long continuous length.What’s more,the construction technology is complex,and the construction period is long.Meanwhile,the structural system and the force are variable.Therefore,it is very significant to study on closure scheme of the rigid frame-continuous composite beam bridge.For the temperature effect and the closure technology of rigid frame-continuous composite beam bridge in cold region,this paper takes the Jinmeng Yellow River Bridge in the cold area as the engineering background,and mainly carries out the following work:(1)Based on the previous research on the temperature field,this paper determines the important parameters of the numerical analysis of the temperature field,such as solar radiation intensity,heat exchange coefficient,ambient temperature,thermal parameters,and uses the finite element software MIDAS/FEA to simulate the transient temperature field of the beam.Then,this paper compares the calculated results and the measured values to verify the feasibility of analysis temperature field by finite element software in engineering.(2)This paper analyzes the temperature distribution of each plate of the box girder,and based on the principle of least squares method,fits the temperature rise and fall temperature gradient curves suitable for the bridge site.At the same time,the paper analyzes the influence law of latitude,longitude,solar radiation intensity and ambient temperature on the temperature field of box girder.(3)This paper establishes the full-bridge MIDAS/Civil model,and calculates the temperature effect of the box girder in the maximum cantilever stage and the completed bridge state by using the fitted temperature gradient curve and compares the calculation results with the China Highway Code(JTG D60-2015).At the same time,the paper analyzes the effect of system temperature rise and fall on the stress and deflection of the whole bridge under different closure temperatures.(4)This paper analyzes the stress distribution law of rigid-continuous beam bridge under live load.Then,the line shape and mechanical behavior of the full-bridge are compared by adjusting the order of the closure section and the demolition timing of temporary consolidation of the continuous piers.At last,this paper proposes the optimal closure plan for the Jinmeng Yellow River Bridge.