Civil Engineering Core Subjects
What is tested
The Civil core paper covers Building Materials, Surveying, Structural Analysis, RCC and Steel Design, Geotechnical Engineering, Hydraulics, Transportation and Environmental Engineering. Expect code-based numbers: grades, permissible stresses, partial safety factors and IRC values.
High-yield rules
- Cement: OPC 33/43/53 grade; initial setting time 30 minutes, final 600 minutes; soundness by Le Chatelier apparatus.
- Concrete: M20 means 20 N/mm² characteristic cube strength at 28 days; a common nominal mix is 1:1.5:3. Limit-state partial safety factors are 1.5 on loads, 1.5 on concrete fck and 1.15 on steel fy.
- Bending: simply supported with UDL gives M = wl²/8 and V = wl/2; a central point load gives M = Wl/4.
- Geotech: Atterberg limits, IS soil classification, SPT N-value, Terzaghi bearing capacity q = cNc + γDfNq + 0.5γBNγ.
- Hydraulics: Bernoulli p/γ + v²/2g + z = constant; Manning v = (1/n)R^(2/3)S^(1/2); Q = AV.
- Transportation: superelevation e = V²/(127R), IRC cap 7% (10% on hill roads without snow).
- Environment: BOD measured at 20 °C over 5 days; sedimentation overflow rate = Q/surface area; chlorine residual about 0.2 mg/L.
Worked example
Superelevation for V = 80 km/h on R = 300 m: e = 80²/(127 × 300) = 6400/38,100 ≈ 0.168, i.e. 16.8%. That exceeds the 7% limit, so the answer needs a larger radius or a speed restriction - always give both parts.
Traps
Feeding design speed in m/s into the superelevation formula, which takes km/h; mixing characteristic and design strengths; quoting 7-day strength as the 28-day value (it is roughly two-thirds); forgetting the partial factor on the material side as well as the load side.