GATE 2019 CE (CE1) – Question 58
Tie bars of diameter 12 mm join concrete pavement slabs. Working tensile stress is 230 MPa, average bond strength 2 MPa and joint gap 10 mm. Ignoring loss of bond and tolerances, find tie-bar design length (mm), to the nearest integer.
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Correct answer: 700 to 700
Explanation
For each side, bar tensile capacity balances bond: $\pi d^2\sigma/4=\pi d\tau l_d$. Hence $l_d=d\sigma/(4\tau)=12(230)/(4\times2)=345$ mm. Two embedment lengths plus the joint gap give $2(345)+10=$ **700 mm**.