SPSC 2011 Assistant Engineer / Assistant Executive Engineer (Civil) BPS-17, Engineers Cadre CCE (2011) — Concrete Technology & Structure Design Paper

Assistant Engineer / Assistant Executive Engineer (Civil) BPS-17, Engineers Cadre CCE (2011) — Concrete Technology & Structure Design. Combined Competitive Examination for Engineers Cadre · Friday 25 March 2011, 10:00 am to 1:00 pm · Max marks 100. Attempt any 05 questions.

1. 1Explain various methods of concrete curing and their impact on final strength of concrete. (20)

2. 2(a) Why in earthquake regions spirally reinforced columns are better than tied columns? (05) (b) Design a square tied column for an ultimate load of 436 kips. Use f'c = 3 ksi, fy = 40 ksi and p = 0.02. (15)

3. 3Explain various types of cements along with their routine tests. (20)

4. 4(a) Determine the allowable ultimate load on a column of 20" diameter circular column section which is reinforced with 6 bars of 1" dia. f'c = 3 ksi, fy = 40 ksi. (10) (b) Design a square column with a cross-section of 12" × 12" and ultimate load of 200 tons; material properties are f'c = 3 ksi, fy = 40 ksi. (10)

5. 5(a) State the principle mechanism of shear Resistance. Explain the Beam and Arch action in shear span. (10) (b) A 20 ft span simply supported beam 10" × 30" carries dead and live load 5 k/ft and 1.5 k/ft respectively. Check the section for the shear and design necessary web reinforcement. Strength of concrete is 3 ksi and steel stress is 40 ksi. (10)

6. 6A rectangular beam has width of 10" and effective depth to the center of tension steel bars at d = 17". Tension reinforcement consists of 6 No. 1" diameter bars in two layers; compression steel consists of 2 bars of 7/8" placed at 2" from top. Calculate the ultimate moment capacity of the beam. f'c = 3 ksi, fy = 50 ksi. Concrete cover at the bottom is 3.5". (20)

7. 7(a) What are the factors which govern the maximum permissible size of the aggregates? Does the size of the aggregate affect the proportioning? (10) (b) What is water cement ratio? Explain in details various factors that affect the strength of concrete. (10)

8. 8Design a reinforced concrete combined rectangular footing for two columns, which are located 14' apart. The overall size of columns is 22" × 22" each and the load carried by each column is 160 tons. The space available for the footing is restricted to 6'. The safe bearing capacity of the soil is 2 tons/ft². Determine the necessary reinforcement and give necessary working drawing for the footing. (20)