Civil Engineering Core Technical Subject
RRB JE CBT 2 Civil tests applied depth across structural analysis, concrete and steel design, geotechnical engineering, hydraulics, transportation, surveying, materials and construction management. Expect numericals and IS-code-based conceptual questions rather than isolated definitions.
Core rules and concepts
- Equilibrium: draw free-body diagrams and use ΣH=0, ΣV=0, ΣM=0. For a simply supported beam under UDL w over span L, maximum bending moment is wL²/8 at midspan and maximum shear is wL/2 at supports.
- IS 456 limit-state design uses partial safety factors: 1.5 for dead/live loads and 1.15 for steel strength; characteristic strength is not the same as design strength.
- Soil: effective stress σ′ = σ − u; use submerged unit weight below the water table. Compaction increases dry density; consolidation is time-dependent.
- Hydrology: rational method Q = CiA with consistent units; leveling reduces staff readings to reduced levels (RL).
- Materials and surveying: check least count, closing error, slump, 28-day cube curing, and nominal versus design mix.
Worked example
A 6 m simply supported beam carries a UDL of 10 kN/m. Maximum BM = wL²/8 = 10×36/8 = 45 kN·m. Maximum shear = wL/2 = 10×6/2 = 30 kN. The BM diagram is parabolic; the shear diagram is linear.
Traps
Mixing kN and N, entering L in cm, applying fixed-end moments to a simply supported beam, comparing characteristic concrete strength with design stress, and using total unit weight instead of effective unit weight below the water table.