Temperature Crack Analysis Of Concrete Box Girder Bridge And Engineering Measures Of It

Temperature crack at early age in concrete is a realistic problem on practical engineering.It as to temperature effect on concrete box beam that directly affects the safety of highway concrete box beam bridage. The research showed that crack in some position of highway concrete box beam bridage was caused by temperature effect.That's because lacking of further research on temperature field of concrete box beam. This paper adopts large finite element analyse software ANSYS to analyse various factors about early stage temperature crack of concrete box girder by exclusive method.The engineering background is based on bottom plate vertical temperature crack appeared during winter construction in Hu-Hang-Yong highway.Meanwhile, some counter measures of construction are simply introducted. The main research work is as follows:1. According to engineering background, It divide the main analysis content into:structural load effect and non-structural load effect, structural load containning gravity,prestress; non-structural load effect contains the winter construction cabinet's internal and external temperature differential,concrete hydration heat,concrete's temperature shrinkage in early stage,early-strength agent's effect to temperature.The crack producted around practical engineering. Gripping related theories to perform finite element analysis to each element and their combination.Finally determine the reason leading to cracking is early temperature crack.caused by non-structral load effect.2. Execute detailed analysis to concrete temperature sterss caused by winter construction cabinet's internal and external temperature differential,and study on the realtions between both;use the method of material uniformed hypothermia in structral mechanics to simulate and analyze concrete box grider's temperature shrinkage effect shrinkage stress;study the effect of early-strength agent to concrete early stage temperature stress,mainly start from concrete linear expansion coefficient's change caused by early-strength agent,qualitatively and quantitatively analyze its effect to box grider temperature shrinkage stree and strain.3. To analyze concrete's temperature effect, it inevitably should study the effect of concrete hydration heat.After concrete's pouring, the hydration heat aggregating in the interior of concrete is uneasily to sporadic,the temperature in the interion of concrete significantly increased,which leads to great temperature diferential,and concrete's surface easily producting crack.this paper briefly take analysis on concrete hydration heat mechanism and its analysis method,brifly give some kinds of common concrete injury models,and take finite simulation on hydration temperature field.4. Throuogh above various factors's analysis,Aimming at practical engineering's crack control,brifly give some coping measures about early temperature shrikage crack.