Civil Engineering Reference
In-Depth Information
Given the measured movements and related temperatures of the expansion
joint, we define the annual
Apparent Coefficient of Thermal Expansion
( A C T E ) of thejoint,
α
, as the slope of the linear regression line describing (at
95% upper confidence level) the relationship between joint movement and
temperature, divided by the expansion length of concrete.
A
10
Total Number of readings = 7181
Range = 14.1 mm
Std. Deviation = 0.778 mm
Std. Deviation Lines
5
Correlation Coeff. R = 0.968
Slope = 0.29324
0
Mean = - 1.7 (mm)
-5
Roof Level Sensor, South Side
-10
Neg. Displ. = Joint Contraction
Pos. Displ. = Joint Expansion
-15
10
Total Number of readings = 7180
Range = 15.51 mm
Std. Deviation = 0.715 mm
Std. Deviation Lines
5
0
Correlation Coeff. R = 0.976
Slope = 0.33579
Mean = - 0.272 (mm)
-5
Level C Sensor, South Side
-10
Neg. Displ. = Joint Contraction
Pos. Displ. = Joint Expansion
-15
-20
-10
0
10
20
30
40
Temperature,
o
C
Fig. 4.21
Annual Joint Movements vs. Temperature
The plots of displacement versus temperature for the entire monitoring period
of one year are shown in Fig. 4.21, along with the linear regression lines. The
annual Apparent Coefficients of Thermal Expansion (ACTE), reported in units of
percent per 100
C, are shown in Table 4.2.
The values of
°
α
obtained from the southern sensors measurements are nearly
70% of the average Coefficient of Thermal Expansion (CTE) of concrete. Said
values are comparable to the coefficients of thermal expansion found in an
unpublished report prepared in 1943-1944 by structural engineers of the Public
Buildings Administration, which presents the expansion joint movement in nine
A
