Civil Engineering
Civil Engineering in IESL Part I covers structural analysis and design, concrete and steel members, geotechnical bearing, hydraulics, surveying and transportation fundamentals. The paper favours short calculations where units, load combinations and effective dimensions decide the answer.
Core rules and concepts
- Simply supported beam with a uniform load w over span L: Mmax = wL²/8 and Vmax = wL/2. For a cantilever, M at support = wL²/2.
- Reinforced concrete self-weight ≈ 24–25 kN/m³; design uses factored loads such as 1.4DL + 1.6LL under BS 8110 practice.
- Effective depth d = h − cover − bar diameter/2. Lever arm z is often approximated as 0.9d for a preliminary check.
- Bearing pressure q = P/A; bearing capacity and settlement are separate checks.
- Surveying: reduced levels from rise and fall; traverse closure and misclosure are checked before adjustment.
- Hydraulics: continuity Q = AV; Bernoulli with head losses.
Worked example
A 300 mm × 500 mm simply supported beam spans 6 m and carries a total uniform load of 20 kN/m, including self-weight. Mmax = 20 × 6² / 8 = 90 kN·m. With 40 mm cover and 20 mm bars, d ≈ 500 − 40 − 10 = 450 mm. Taking z = 0.9d = 405 mm and fy = 460 N/mm², As ≈ M / (0.87 fy z) = 90 × 10⁶ / (0.87 × 460 × 405) ≈ 556 mm². The reasoning is to find the bending moment first, then use the lever-arm approximation to estimate steel area.
Traps that cost marks
- Omitting self-weight or using the wrong span (clear versus effective).
- Mixing kN and N, or mm and m, in the moment equation.
- Treating bearing capacity as a settlement check.
- Forgetting minimum reinforcement and durability cover.