CE-601 Structural Design and Drawing (RCC-I) - Dec 2024 Question Paper

Under each question, How to answer lists the points an answer should cover, outlined by CampusPrep from the syllabus. Check the details against your textbook.

1. 5 Marks
   aDerive Stress Block Parameters as per the Limit State Method.
   How to answer

   • Define limit state stress block as per IS 456: parabolic-rectangular for M-grade concrete
   • Maximum strain 0.0035 at extreme compression fibre
   • Derive C1 for rectangular part and C2 for parabolic part, location of resultant
   • Obtain parameters: total compression 0.36 fck b xu, centroid at 0.42 xu from top
2. 5 Marks
   bCompare 'Working Stress Method' and Limit State Design of RCC Structures. Explain the answer with suitable examples.
   How to answer

   • Define Working Stress Method: elastic, allowable stresses
   • Define Limit State Method: ultimate load + serviceability, partial safety factors
   • Compare on assumptions, safety, economy, serviceability
   • Give suitable examples e.g., beam design by both methods
3. 4 Marks
   cWhat is meant by Limit State? Mention different limit states to be considered in R.C.C design.
   How to answer

   • Define limit state: state beyond which structure no longer satisfies design criteria
   • List limit state of collapse: flexure, shear, torsion, buckling
   • List limit state of serviceability: deflection, cracking, vibration, durability
   • Mention IS 456 consideration in R.C.C design
4. 10 Marks
   aSimply supported beam of C/S $350 \times 700$ mm is provided with (5#25 + 5#20) on the tension side and 4#25 on the compression side. Calculate moment of resistance. Grade of concrete is M25 with severe exposure. Grade of reinforcement is Fe550.
   How to answer

   • Calculate Ast tension for (5#25 + 5#20) and Asc for 4#25
   • Determine effective depth with severe exposure cover, find xu from equilibrium
   • Check xu vs xu,max for Fe550, decide doubly reinforced case
   • Calculate moment of resistance $M_u = 0.36 f_{ck} b x_u (d-0.42x_u) + f_{sc} A_{sc}(d-d')$
5. 4 Marks
   bExplain about limit state design for serviceability.
   How to answer

   • Define serviceability limit states: deflection, cracking, vibration
   • Explain IS 456 clauses for span/effective depth, crack width limits
   • Explain durability and exposure considerations
   • Summarize design checks to ensure serviceability
6. 14 Marks
   Design a dog legged staircase for an office building, given the following data: Height between floor = 3.2 m; Riser = 160 mm, Tread = 270 mm; Width of flight = 1.25 m; Live load = $5 kN/m^2$ ; Finishes load = $0.6 kN/m^2$ . Assume the stairs to be supported on 230 mm thick masonry walls at the outer edges of the landing, parallel to the risers. Adopt mild exposure with M20 grade concrete and Fe415 steel. Also sketch the reinforcement details.
   How to answer

   • Calculate flights, going, effective span for 3.2 m floor height
   • Compute loads: dead + finishes $0.6 kN/m^2$ + live $5 kN/m^2$ factored
   • Design waist slab thickness, calculate Mu and Ast with M20/Fe415
   • Detail reinforcement and sketch plan, section and distribution steel
7. 14 Marks
   Design a R.C. slab for a room measuring $4 m \times 6.5 m$. The slab carries a live load of $2.5 kN/m^2$. The slab is simply supported at all the four edges with corners free to lift. The width of the supporting walls is 300 mm. Use M 30 grade concrete and Fe 500 grade steel. Adopt Limit State method. Sketch the reinforcement details. Assume mild exposure condition.
   How to answer

   • Determine ly/lx for $4 m \times 6.5 m$ room, classify two-way slab
   • Compute effective span, depth from deflection control, factored loads
   • Calculate Mx, My using IS 456 coefficients, design Ast both ways
   • Sketch reinforcement details including torsion steel at corners
8. 14 Marks
   Design a circular column of diameter 300 mm to carry a factored axial load of 1500 kN by using: (a) Helical reinforcement, (b) Hoop reinforcement. Use M20 concrete and Fe415 steel.
   How to answer

   • Calculate factored load $P_u = 1500 kN$, determine gross area required
   • Design longitudinal steel and (a) helical pitch as per IS 456
   • Design (b) hoop / tie alternative with diameter and spacing
   • Check minimum eccentricity and detailing for 300 mm dia column
9. 7 Marks
   aList the steps involved in the design of combined footings.
   How to answer

   • Define combined footings need, proportion base area from SBC
   • List steps: shear and moment diagrams, width, depth check
   • List steps: design longitudinal and transverse reinforcement, detailing
10. 7 Marks
    bList the steps involved in the design of Strap footing.
    How to answer

    • Define strap footing concept: two isolated footings connected by strap beam
    • List steps: proportion footings, analyze strap beam as inverted
    • List steps: shear/moment design, detailing of strap and footings
11. 5 Marks
    aDraw the cross-section of singly reinforced rectangular beam and show the strain and stress diagrams.
    How to answer

    • Draw rectangular section with steel at effective depth
    • Draw linear strain diagram 0.0035 to steel strain
    • Draw parabolic-rectangular stress block with 0.36 fck and 0.42 xu
    • Label neutral axis, compression and tension zones
12. 4 Marks
    bExplain the critical sections for design shear as per IS 456 with requisite sketches.
    How to answer

    • Define nominal and design shear strength per IS 456
    • Identify critical sections: support face, d away for uniform load
    • Explain sections in continuous beams, point loads
    • Provide requisite sketches of sections
13. 5 Marks
    cExplain the approaches for control of deflection in bending members as per IS 456. What are the measures for reducing deflection?
    How to answer

    • State IS 456 span/depth ratios for deflection control
    • Explain modification factors for tension and compression steel
    • Explain cracking, span, loading effects and camber
    • List measures: increase depth, compression steel, reduce span, high grade
14. 4 Marks
    aLever arm and Moment of resistance.
    How to answer

    • Define lever arm $z = d-0.42x_u$ and $M_u$ expression
    • Explain balanced/under/over-reinforced significance
    • Give formula and diagram reference
15. 4 Marks
    bAnchorage and Development length
    How to answer

    • Define anchorage and development length $L_d = \phi \sigma_s / 4\tau_{bd}$
    • Explain factors: bond stress, hooks, bends
    • Mention IS 456 codal values and checks
16. 6 Marks
    cShear reinforcement and Torsion reinforcement
    How to answer

    • Define shear reinforcement: stirrups, bent-up bars design
    • Define torsion reinforcement: longitudinal + transverse per IS 456
    • Differentiate purpose and detailing
    • Give sketches/formulas for spacing