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Design of Concrete Structure I Eng. Tamer Eshtawi First Semester 2008 Eng. Tamer Eshtawi First Semester 2008

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Lecture 3 Loads ACI 318-05

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Dead Load (Slab & Beam) Concrete structural system

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Dead Load (Slab & Beam) Slab types Solid slab One-way slab Two way slab Ribbed Slab one way or two way according to rib system The effect of slab type Oneway slab Two-way slab

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Solid slab Ribbed Slab One-way slabTwo way slab One-way slabTwo way slab

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Dead Load (Slab & Beam) Minimum thickness of Beams & one-way ribbed slabs Cantilever Both ends continuous One end continuous Simply supported Element L/8L/21L/18.5L/16 One-way ribbed slabs & Beams

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Different type of Ribbed slab according to thire position

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Total volume (hatched) = 0.52 x 0.25 x 0.25 = 0.0325 m 3 Volume of one hollow block = 0.4 x 0.20 x 0.25 = 0.02 m 3 Net concrete volume = 0.0325 - 0.02 = 0.0125 m 3 Weight of concrete = 0.0125 x 25= 0.3125 kN Weight of concrete /m 2 = 0.3125/(0.52)(0.25) = 2.4 kN/ m 2 Weight of hollow Blocks /m 2 = 20(10)/(0.52)(0.25)(1000) = 1.54 kN/ m 2 Total Slab dead load = 2.4 + 1.54 = 3.94 kN/m 2 (4 kN/m 2 ) depth 25 cm(17cm block +8cm concrete) Dead Load (Slab own weight ) assume depth 25 cm (17cm block +8cm concrete)

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Dead Load (Covering Material) thickness weight/m 2 Tiles2.5cm 1*1*0.025 * 22KN/m 3 =0.55KN Morter2.5cm 1*1*0.025 * 20KN/m 3 =0.50KN Sand6cm 1*1*0.060 * 18KN/m 3 =1.08KN Concreteh Plaster1.5cm 1*1*0.015 * 20KN/m 3 =0.30KN 2.41KN/m 2 2.5 kN/m 2 Covering material (dead load) = 2.5 kN/m 2 Total Dead Load = Slab own weight + Covering material = 4 + 2.5 = 6.5 kN/m 2

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Dead Load (Walls) Each of wall contains 12.5 blocks The weight of each block: 20 kg for block with thickness 20cm 10 kg for block with thickness 10 cm Each face of 1m 2 has 30kg plaster For 20 cm block wt. = 12.5 * 20 +2*30=310 kg/m 2 = 3.1 KN/m 2 For 10 cm block wt. = 12.5 * 10 +2*30=185 Kg/m 2 = 1.85 KN/m 2

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3 m 1 m Weight for 1 m length For 20 cm block wt. = 9.3 KN/m 3.1 KN/m 2 * 3 = 9.3 KN/m For 10 cm block wt. = 5.6KN/m 1.85 KN/m 2 * 3 = 5.6KN/m

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Minimum live Load values on slabs Type of UseUniform Live Load kg/m 2 Residential Residential balconies 200 300 Computer use500 Offices250 Warehouses Light storage Heavy Storage 600 1200 Schools Classrooms200 Libraries rooms Stack rooms 300 600 Hospitals200 Assembly Halls Fixed seating Movable seating 250 500 Garages (cars)250 Stores Retail wholesale 400 500 Exit facilities500 Manufacturing Light Heavy 400 600 Live Load

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A structural Design code A structural Design code is a code that involves the design of a certain type of structures (reinforced concrete, structural steel, etc.). The structural code that will be used extensively throughout this course is The American concrete Institute (ACI-318-05), which is one of the most solid codes due to its continuing modification, improvement, and revision to incorporate the latest advancements in the field of reinforced concrete design and construction.

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Design Methods The Ultimate – Strength Design Method At the present time, the ultimate-strength design method is the method adopted by most prestigious design codes In this method, members are designed such that the internal forces in the members produced by factored loads do not exceed the corresponding strength capacities and allowing for some capacity reduction.

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The Working-Stress Design Method Before the introduction of the strength-design method in the ACI building code in 1956, the working stress design method was used in design. This method is based on the condition that the stresses caused by service loads without load factors are not to exceed the allowable stresses which are taken as a fraction of the ultimate stresses of the materials, for concrete and for steel

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Load Factors In this course, we will us this load factor U =1.2 D + 1.6 L

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Strength reduction Factor

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