Reinforced Concrete I. Operation of Rational Numbers  Addition: = 8 (The equation expressed in English is five plus three equals eight, in which 5 is defined as addend, 3 as addend or augend, and 8 as sum or total.  Subtraction: 7 – 3 = 4 (The equation expressed in English is seven minus three makes four, in which 7 is defined as minuend, 3 as subtrahend, and 4 as remainder or difference.)  Multiplication: 3 x 4 = 12 (The equation expressed in English can be three times /by/ multiplied by four makes twelve, in which 3 is defined as multiplicand, 4 as multiplier, and 12 as product.) 1 Friday, June 03, 2016

Reinforced Concrete I. Operation of Rational Numbers 4. Division: 1) 8 ÷ 4 = 2 (The equation expressed in English can be eight divided by four makes two, in which 8 is defined as dividend, 4 as divisor, and 2 as quotient.) 2) 9 ÷ 4 = 2 … 1: (The equation expressed in English can be nine divided by four makes two and one over, in which 9 can be called partial dividend and 1 as remainder.) 4. Power 3 2 = 3 x 3 = 9 Three squared equals three times three equals nine. 2 3 = 2 x 2 x 2 = 8 Two cubed equals two times two times two equals eight. 2 4 = 2 x 2 x 2 x 2 = 16 The fourth power of two equals two times two times two times two equals sixteen. 2 Friday, June 03, 2016

Reinforced Concrete I. Disadvantages of plain concrete Weak in tensile strength II. *The disability of plain concrete is overcome in two ways: reinforced concrete (RC) and prestressed concrete (PC).reinforced concrete 1. Reinforced concrete is plain concrete in which steel rods or bars ("rebars") have been incorporated to reinforce the naturally brittle concrete.concretesteelrebars III. *Function of Steel and concrete in RC 1.Steel takes up a small quantity but a major part of the cost (the cost of the formwork, the cost of the concrete and the cost of the steel are approximately the same) 2.Concrete takes the compression, steel takes the tension. 3 Friday, June 03, 2016

Reinforced Concrete III. Function of Steel and concrete in RC 3. Steel is the vital part of the structure due to the deficient tensile strength of concrete; 4. The coverage of concrete prevents steels from rapid rusting; 5. The proper adhesion between the steel and the concrete is of the greatest importance, and bars should be of a sufficiently small diameter; 6. The bars should be limited so that they do not obstruct the proper placing the concrete and so as to provide adequate space for the reinforcement to develop the stress by transmission from the concrete; 4 Friday, June 03, 2016

Reinforced Concrete 7. Individual reinforcing bars generally do not exceed 12 m (39ft) in length. IV. *Advantages of RC 1. Advantages of concrete: low cost, good weather and fire resistance, good compressive strength, excellent workability/formability 2. Advantages of steel: high tensile strength, greater ductility, toughness 3. Advantages of combination of steel and concrete 1) Relatively low cost 2) Good weather and fire resistance 3) Good compressive strength 4) Excellent formability 5) Considerably high tensile strength 5 Friday, June 03, 2016

Reinforced Concrete V. *Disadvantages of RC 1. Cracking is inevitable which is induced by the mere process of the reinforcing steel being stressed under the normal working loads 2. The higher steel stress increases the strain of the concrete 3. Stress v.s. Strain 1) stress: the force per unit area 2) Strain: the elongation per unit length VI. HomeworkHomework 6 Friday, June 03, 2016