Thermal Stress Analysis And Rebar Design On Continuously Reinforced Concrete Pavement In Cold Region

Recently, along with the economic persistent and healthy developing, theconstruction of traffic basic establishment has also developed. Our freewaymileage has exceeded 34 kilometer, it is the second in the world. But in high-gradehighway, cement concrete pavement and bitumen concrete pavement are themostly type. Compared with bitumen concrete pavement, the cement concretepavement has long life. But as the juncture survives, the comfort is not as good asbitumen concrete pavement. And in the juncture, it is easy to bring many wrecks.To settle this problem, many scholars inside and outside the country do largeamount of experiment and research, then bring forward many new design methodsand theories. And CRCP is one of the new concrete pavement types.When the scholar inside and outside our country having research on thereinforced concrete structure, by a series of experiment they find the bond-slipbetween rebar and concrete. Many of these theories have applied on finite analysis.The study indicates that when we calculating the crack width, the calculatingresults of not considering the slip between rebar and concrete is well matches theexamination results. And when not considering the slip, the results are different tothe examination results. In CRCP, the crack width is an important design index.So in CRCP, we should not only consider bond and also consider the slip. Thispaper puts the bond-slip theory between rebar into CRCP design. Choose adifferential coefficient section to do mechanical analysis. In the analysis,considering the relative slip between rebar and concrete is small, for predigestingcalculation we adopt linearity model and use bond stiff coefficient k c. By analysisand calculate on differential coefficient model, do contrast analysis of the resultsof considering ground resistance and not considering ground resistance, then findout that the ground resistance has small impact on CRCP. So when we analyze thepractice problem, we could ignore the impact of ground resistance.This paper adopts the widely used finite-element analysis software ANSYS tosimulate and analyze CRCP. The model does not consider the ground resistance.In the finite-element analysis, concrete uses SOLID65 element, the rebar usesLINK8 element. Use COMBIN14 to simulate the bond and slip relation betweenrebar and concrete. When simulate the bond between rebar and concrete, we usespring element COMBIN14 of zero length. It could produce flexible alongx-direction. When the rebar and concrete come into slippage, it could simulate thebond and slip between rebar and concrete. This element is easier than contactelement, and could largely economize the counting time. By the finite-elementmodel we calculate on the crack width and temperature stress of CRCP. Contrastbetween the numerical value and resolving value. We can find that the two resultsare the same. So we consider that to use the SOLID65 element,LINK8 element,COMBIN14 element to set up the separated finite model is correct. We can usethis model to simulate the temperature stress and crack width of CRCP. In themodel, by changing varies of design parameter, we can find that: the crack spacehas obvious impact on crack width, rebar and concrete stress. If the crack space islong, the crack width, rebar and concrete stress is big, contrarily it is small;If thebond coefficient between rebar and concrete is large, the crack width is small;Ifthe concrete line expanding coefficient is large, the crack width, rebar andconcrete stress is large;The increasing of reinforcement ratio could decrease crackspace and crack width. At the same time, the rebar decreased and concrete stressincreased. The parameter of concrete road surface plate thickness and so on hassmall impact on crack width,rebar and concrete stress. Holding these changingrules is helpful to design the CRCP.Make use of the finite-element model and combine our criterion for crack spaceand crack width to design the CRCP reinforcing. From this paper we know that theCRCP thickness can directly adopt common concrete plate design rule and neednot consider the boosting-up effect of CRCP reinforcing to concrete plate. Whendesigning the reinforcing, we use the screw thread rebar. And put the rebar in h/2of the plate. When design the portrait rebar, we first assume the reinforcing ratioand rebar diameter, then calculate the crack space and use ANSYS to calculate thecrack width and rebar stress. If the crack width and rebar stress is not up to themustard, we should adjust the reinforcing ratio and rebar diameter. Finally wecalculate the project of reinforcing ratio is 0.70%, the rebar diameter is 20mm, thereinforcing space is 180mm is good. And we can know by contrasting severalreinforcing project that if the crack space satisfies the request, the rebar diametershould adopt small diameter. Small diameter and small space is in favor ofelevating the bond force between rebar and concrete.