ADMIXTURE AND CONCRETE MIX PROPORTIONS

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ADMIXTURES Admixtures are added to the concrete before or during mixing, to modify one or more of the specific properties of concrete in the fresh or hardened states. IS:9103-1979 lays down the procedures for evolution of admixtures for concrete The different types of admixtures used are given below. 1. Accelerating Admixtures: These are added to … Read more

CONCRETE AND INGREDIENTS OF CONCRETE

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CONCRETE Concrete structures have become very common in Civil engineering construction Concrete has established as a universal building material because of its high compressive strength, its adoptability to take any form and shape and resistant to fire and corrosion with negligible maintenance cost. Concrete is very strong in compression but very weak in tension. Its … Read more

Q.Draw S.FD and B.M.D for the following beam and also calculate the position of the point of contra flexure.

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Q.Draw S.FD and B.M.D for the following beam and also calculate the position of the point of contra flexure. SOLUTION: Total load = 30×11+80= 330 + 80 = 410 To find reactions: Taking  moments about A: RB * 9 = (30 * 11) * 11/2 + 80 * 11 = 1815 + 880 = 2695 … Read more

Q. A beam ABCD is supported at A and D such that AB = 1.5 BC = 2.5 m and AD = 5m . It carries point loads of 30 kN and 20 kN at B and C respectively. It also carries a udl of 10 kN/m including self weight on entire span. Draw SFD and BMD.

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SOLUTION: Total load= 10 * 5 + 30 + 20 = 100kN To find reactions: R{D} * 5 = (10 * 5) * 5/2 + 30 * 1.5 + 20 * 4 = 125 + 45 + 80 = 250 R{D} = 250/5 = 50kN R{A} = 100 – 50 = 50kN SFD (SHEAR FORCE … Read more

Q.A simply supported beam of span 10 m is subjected to 20 kN, 30 kN, 50 kN and 20 kN loads respectively at 1 m, 3m, 5 m and 8 m from left hand support. Draw the S.F.D and B.M.D indicating the values at salient points.

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SOLUTION: Total load = 20 + 30 + 50 + 20 = 120kN To find reactions: Taking moments about A R{B} * 10 = 20 * 1 + 30 * 3 + 50 * 5 + 20 * 8 . .= 20 + 90 + 250 + 160 = 520kN R{B} = 520/10 = 52kN … Read more

Q. A cantilever beam of span 2 m carries three point loads of 2 kN, 1 kN and 1 kN at a distances of 0.3 m. 1.2 m and 2 m respectively from fixed end. Draw S.F and B.M diagrams and find maz, bending moment and indicate where it occurs.

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SOLUTION: Total load on the beam = 2 + 1 + 1 + 4 KN S.F.D: (SHEAR FORCE DIAGRAM) S.F at A = 4kN SFat C = 4 – 2 = 2kN(just right of C) SF at C = 4kN (just left D) SF at D = 2 – 1 = 1kN(just right of D) … Read more

Q. A cantilever beam of span 3 m carries a udl of 2kN / m over a span of 2 m from fixed end. In addition a point load of 2 kN placed at the free end. Draw the S.F and B.M diagrams with critical dimensions.

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Q. A cantilever beam of span 3 m carries a udl of 2kN / m over a span of 2 m from fixed end. In addition a point load of 2 kN placed at the free end. Draw the S.F and B.M diagrams with critical dimensions. SOLUTION: Total load = 2 * 2 + 2 … Read more

Q. A beam 9 m long carries an udl of 20 kN/m on the entire span. The beam has an overhang of 1.5m and 1.5 m after left hand support and right hand support respectively. The spacing between the supports is 6 m. Draw the SFD and BMD indicating the values at salient points.

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SOLUTION: Total load = 20 * 9 = 180kN To find reactions As the loading on the beam is symmetrical then R{A} = R{B} = 180/2 = 90kN SFD ( SHEAR FORCE DIAGRAM) F{C} = F{D} = 0 F{A} (just left of A)= – 30kN F{A} (just right of A)=+ 60kN F{B} (just left of … Read more

Q. A beam ABCDE of 8 m length with double over hang is loaded as shown in figure. Draw SFD and BMD.

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Q. A beam ABCDE of 8 m length with double over hang is loaded as shown in figure. Draw SFD and BMD. SOLUTION: Total load= 10 + 40 + 20 + (6 * 6) = 106 kN To find reactions Taking moments about B (Anticlockwise moment = clockwise moment) R{D} * 5 + 10 * … Read more

Q. An overhanging beam is shown in the following figure. Draw she force and bending moment diagrams.

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Q. An overhanging beam is shown in the following figure. Draw she force and bending moment diagrams. SOLUTION: Total load = 3 * 2 + 20 + 10 + 5 * 4 = 56kN To find the reactions Taking moments about A Anticlockwise moments = clockwise moments R{B} * 7 + (3 * 2) * … Read more