You are given the job of designing a bridge that is to be made of concrete slabs that rest on a steel support frame. The total length of the bridge is 304 m, and you want to be sure that the expansion joints are sufficiently large. If the temperature increases by 28°C, what is the difference in the new lengths of the concrete and steel components of the bridge?
concrete _______m
steel ______m
Which of these components will have the largest increase in length? (The two components are considered expanded by the same amount if their expansions are within 5% of each other. a)concrete b)steel c)they both expand by the same amount
Solution
change in length are perposational to the coefficient of terminal expention alpha with
deltaL/L 0 = alpha*deltaT ........1
given that
L o = 304 m
coefficient of thermal expantion of steel alpha = 12*10^-6 k -1
coefficient of thermal expantion of concrete alpha c = 12*10^-6 k -1
change in the temperature delta T = 28 K
consider the length of the bridge and neglet the expention of the total joints in the bridge
expantion of steel support frame is caculated by using equ. 1
delta L = L 0 *alpha*deltaT
= 304*12*10^-6*28
= 10.2144*10^-2 m
expansion of concrete slabes is calculated by using equ. 1
deltaL = L 0 *alpha c *deltaT
= 304*12*10^-6*28
= 10.2144*10^-2 m
from the calculation that the steel and concrete expance equally bcs of the same coefficient of the linear expantion the difference in the length of the steel and concrete expantion is zero.as both expand equally.
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You are given the job of designing a bridge that is to be made of conc (1).docx
1. You are given the job of designing a bridge that is to be made of concrete slabs that rest on a
steel support frame. The total length of the bridge is 304 m, and you want to be sure that the
expansion joints are sufficiently large. If the temperature increases by 28°C, what is the
difference in the new lengths of the concrete and steel components of the bridge?
concrete _______m
steel ______m
Which of these components will have the largest increase in length? (The two components are
considered expanded by the same amount if their expansions are within 5% of each other.
a)concrete b)steel c)they both expand by the same amount
Solution
change in length are perposational to the coefficient of terminal expention alpha with
deltaL/L 0 = alpha*deltaT ........1
given that
L o = 304 m
coefficient of thermal expantion of steel alpha = 12*10^-6 k -1
coefficient of thermal expantion of concrete alpha c = 12*10^-6 k -1
change in the temperature delta T = 28 K
consider the length of the bridge and neglet the expention of the total joints in the bridge
expantion of steel support frame is caculated by using equ. 1
delta L = L 0 *alpha*deltaT
= 304*12*10^-6*28
2. = 10.2144*10^-2 m
expansion of concrete slabes is calculated by using equ. 1
deltaL = L 0 *alpha c *deltaT
= 304*12*10^-6*28
= 10.2144*10^-2 m
from the calculation that the steel and concrete expance equally bcs of the same coefficient of the
linear expantion the difference in the length of the steel and concrete expantion is zero.as both
expand equally.
