Vertical Temperature Difference of Steel Box Girder Bridge Considering Asphalt Thickness of Concrete Deck

콘크리트 바닥판의 아스팔트 두께에 따른 강박스거더교의 상하 온도차

Abstract

The purpose of this study was to calculate the temperature difference of the sectional elevation according to the asphalt thickness of the steel box girder bridge deck and provide data on the design basis accordingly. Asphalt thicknesses produced four steel box girder model specimens of 0mm, 50mm, 100m and 150mm. In each model, 17 to 23 temperature sensors were attached to upper concrete and steel box girders. Six temperature gauges were selected to compare the temperature difference with Euro codes. The maximum and lowest temperature were calculated at the reference atmospheric temperature of each model, and the temperature difference (slope) was calculated based on this calculation. Four models of temperature difference are presented at each model. The 0mm to 100mm temperature difference models showed a -0.9 to -1.5 degree lower temperature difference compared to the temperature difference of Euro codes at the top of the slab. Overall, the measured temperature difference was found to be between 5.45% and 8.33% compared to the Euro code. The standard error coefficient, which was calculated by multiplying the average temperature with the standard error, was calculated from a range of 2.50 to 2.51 times the average at the top and bottom. It is estimated that the proposed temperature difference model can be used as a basic data when calculating temperature difference criteria for bridges in Korea.

본 연구에서는 강박스거더교 바닥판의 아스팔트 두께에 따른 단면 상하 온도차를 산정하고, 이에 따른 설계기준의 자료를 제공하고자 하였다. 아스팔트 두께 0mm, 50mm, 100m, 150mm의 4개 강박스거더 모형시험체를 제작하였다. 각 모형에 17~23개의 온도 센서를 상부 콘크리트와 강박스거더에 부착하였다. 이 센서 중 Euro code와 온도차를 비교 할 수 있는 6개의 온도 게이지를 선정하였다. 각 모형의 기준 대기온도에서 최대 온도와 최저 온도를 계산하고, 이를 바탕으로 온도차(경사)를 산정하여, 4개 각 모형에서 온도차 모델을 제시하였다. 0mm ~ 100mm 온도차 모델은 슬래브 최상단에서 Euro code의 온도차와 비교할 때 -0.9~-1.5도 더 낮은 온도차를 보였다. 전체적으로 측정된 온도차는 Euro code와 비교하여 5.45%~8.33%정도의 오차가 있음을 확인하였다. 산정된 온도와 평균온도의 차를 표준오차의 배수로 산정한 표준오차 계수는 최상단과 최하 단에서 평균 2.50 ~ 2.51배의 값으로 일정한 범위에서 산정되었다. 제시된 온도차 모델은 국내 교량 온도설계 온도차 기준 산정 시 기본 자료로 활용될 수 있을 것으로 판단된다.

Fig. 1. Complete view of bridge specimens (a) 2016 (b) 2017

Fig. 2. Plan of the bridge models with azimuth angle.

Fig. 3. Section and gauge numbers of 50mm specimen

Fig. 4. Temperature difference for Group 3, Concrete deck on steel box (Euro code)[4]

Fig. 5. Vertical variation of temperature on concrete and upper steel structures

Fig. 6. The measured temperature data of 2 years summer (a) 2016 (b) 2017

Fig. 7. Connection of the cross section of a specimen with the Euro code

Fig. 8. Distribution of temperature at each point (a) SC24 (b) SC3 (c) SC13

Fig. 9. Distribution of temperature at SC24 of each model (a) 0mm (b) 50mm (c) 100mm (d) 150mm

Fig. 10. The models of temperature difference at each asphalt thickness in present model and Euro code (a) 0mm (b) 50mm (c) 100mm (d) 150mm

Table 1. Temperature difference ( T₁ ) for Group 3 (Euro code)[4]

Table 2. Basis for temperature gradients

Table 3. Calculation of temperature difference in 0mm

Table 4. Calculation of temperature difference in 50mm

Table 5. Calculation of temperature difference in 100mm

Table 6. Calculation of temperature difference in 150mm

Table 7. The average maximum atmospheric temperature of the weather station

Table 8. Calculation of Temperature difference in the present model and the Euro code