Study On Hydration Temperature Effect Of Block 0 Of Long-Span PC Continuous Box Girder Bridge

In recent years,with the development of the society and the progress of the construction technology,the span of the highway bridges built is becoming larger and larger.At present,the long-span concrete bridges are widely used in prestressed concrete continuous beam bridges.The pouring quality of No.0 block concrete plays an important role in the construction of the bridge.The hydration heat effect of mass concrete structure is analyzed,the distribution characteristics of temperature field are defined,and the time-history variation law of temperature stress is obtained.In order to ensure the quality of engineering structure and improve the durability of engineering structure,the preventive measures of temperature crack are discussed.Based on the theoretical analysis method of hydration heat of mass concrete and relying on solid engineering,this paper analyzes the temperature effect of hydration heat on block 0 of K3 pier of a large span PC continuous box girder bridge in Changchun.The main contents of the work are as follows:(1)by consulting the relevant data at home and abroad,collecting the knowledge of thermodynamics theory,the thermodynamic properties of concrete are summarized,and the three theoretical calculation methods of hydration heat temperature effect are briefly introduced.The advantages and disadvantages of various methods are analyzed,which provides theoretical support for the establishment of finite element model of block 0 of K3 pier and the analysis of temperature effect.(2)based on K3 Pier 0 block,the temperature monitoring cross section of K3 Pier 0 block transverse beam(with the largest cement content and the most remarkable hydration heat effect)section 1-1 and the end of No.0 block 2-2 section are selected,and the temperature measuring points of the monitoring section are arranged.The field measured data were collected and the variation law of temperature time history of each measuring point was analyzed.The temperature distribution characteristics of block 0 of K3 pier were summarized,which provided the measured data support for the control measures of hydration heat temperature.(3)the finite element model of block 0 of K3 pier is established by using Midas civil finite element software.The simulation results of the finite element model are compared with the measured data to verify the accuracy of the finite element model,and the distribution characteristics of the cloud diagram of hydrated heat field are analyzed.At the same time,the temperature stress of block 0 of block K3 is analyzed,and the tensile stress(caused by temperature)of block 0 is compared with the allowable tensile stress of the structure.By combining theory with practice,the relevant matters needing attention in concrete pouring process are put forward.(4)through collecting the relevant prevention measures of temperature crack and combining with engineering practice experience,the paper discusses the prevention and treatment measures of the temperature crack of K3 pier 0 block,in order to ensure the quality of concrete engineering structure integrity and durability.The conclusions can be used as reference for engineering practice.