STUPIDSID
Answer any one question from Q1 and Q2
1 (a)
Explain with neat sketches various systems of Pre stressing.
5 M
1 (b)
Explain in detail various types of losses in post tensioned member.
5 M
1 (c)
An Unsymmetrical I-Section of size top flange 500×200 mm, Bottom flange 350×250 mm and web 150×600 mm is used to support an imposed load of 15 KN/m over a span of 16 m. the effective pre stressing force of 1250 KN is located at 90 mm From soffit of the section at mid span. Cable profile is parabolic and concentric at Support calculates the extreme fiber stresses in concrete at mid span at initial and final stages. Take loss ratio as 0.82.
15 M
2 (a)
State what are the remedial measures to be taken to reduce losses in prestress.
8 M
2 (b)
A post tensioned prestressed concrete beam is simply supported over a span of 20m having cross sectional dimensions of top flange as 500 × 200mm, web 150 × 800 mm and bottom flange 400× 250 mm. the beam is prestressed with 5 no? of 12/5 Freyssinet parabolic cables with their C.G at 120 mm from extreme bottom fire cables are stressed one at a time from one end only with pre stressing force of 1000KN. Calculate total loss of prestress and jacking force at the age of 100 days, if coefficient of friction is 0.3, coefficient of curvature and wave effect = 0.0026/m length of cable, slip of anchorage at jacking end = 2 mm, creep coefficient = 2.4, Es=200 Gpa, Creep and relaxation of steel= 1 % of initial prestress, Concrete grade=M 40.
17 M
Answer any one question from Q3 and Q4
3
Design a post tension prestressed concrete beam using I section for flexure to carry a live load of 15 KN/m over a simply supported span of 18 m with M 40 grade of concrete and Freyssinet cables of 12/5 (fy =1750 Mpa) or 12/7 (fy =1500Mpa), design the end block also. Draw sketches showing details of cable profile, end block reinforcement, check fiber stress in concrete and deflection.
25 M
4 (a)
Explain need of High strength steel and high strength Concrete in Prestress Concrete construction.
7 M
4 (b)
A post tension prestress concrete two way slab of 7m×9m with discontinuous edges to support imposed load of KN/m2 use S3 cable having area of each 100 mm2, and fy=1800 Mpa. Check the safety of slab against collapse and deflection at service load. Use M40 concrete.
18 M
Answer any one question from Q5 and 6
5
Fig (1) Shows an intermediate frame of multistory building the frames are spaced at 4.5 m center analyze a rigid jointed frame taking live load 3 KN/m2 and dead load as 4 KN/m2 for panels AB and BC respectively. Self weight of beam may be taken as for 7m span=5 KN/m and for 5m Span=4KN/m. the relative stiffness of the member are as shown in the fig. use portal method for horizontal loads and proper substitute frame for vertical loads. Design the beam ABC for combined effect of horizontal and vertical loads. Use 20% redistribution of moments for vertical load moments. Use M25 and Fe 500.
25 M
6 (a)
Write detail note on substitute frame method.
8 M
6 (b)
Analyze the rigid jointed frame as shown in fig (3) by cantilever method for Lateral loads. Flexural rigidity for all members is same. Analyze beam GHI using Proper Substitute Frame, if it is subjected to vertical ultimate live & Dead load including its self weight of intensities 15 KN/m and 12 KN/m on Span GH and 20 KN/m and 15 KN/m on HI respectively. The horizontal forces are as shown in fig. Calculate maximum span moment for HI and support moment at H. design section for combined effect of vertical and horizontal loads. Adopt 15% redistribution of moments for vertical load moments. Use M20 and Fe 500.
17 M
Answer any one question from Q7 and Q8
7
Design a T-shaped retaining wall for two layered leveled backfill for the following Data
Upper layer, Height=2.5m, ϕ=30°, density of material=16KN/m3. Lower layer, Height=2.5m, ϕ=32°, density of material=18KN/m3. Safe bearing capacity of underlying strata is 195 KN/m2 the coeff. Of friction between base and underlying strata is 0.45 .Draw lateral pressure diagram and details of reinforcement in stem and base slab including curtailment if any. Use M25 and Fe 500.
Upper layer, Height=2.5m, ϕ=30°, density of material=16KN/m3. Lower layer, Height=2.5m, ϕ=32°, density of material=18KN/m3. Safe bearing capacity of underlying strata is 195 KN/m2 the coeff. Of friction between base and underlying strata is 0.45 .Draw lateral pressure diagram and details of reinforcement in stem and base slab including curtailment if any. Use M25 and Fe 500.
25 M
8
Design a slab and Beam type rectangular combined footing for two columns A and B carrying working load 650 KN and 80 KN respectively column A is 230 mm × 375 mm and column B is 230 mm × 40 mm. center to center distance between the columns is 3.0 m and the property line is at 0.9 m from the faces of column A. assume SBC of soil is 180 KN/m2 Use M20 and Fe 500. Draw details of reinforcement in slab and central beam.
25 M
More question papers from Structural Design & Drawing- III