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2.0 ANALYSIS AND DESIGN 2.2 STRUCTURAL ELEMENT Reinforced Concrete Column Rearrangement by :- NOR AZAH BINTI AIZIZ KOLEJ MATRIKULASI TEKNIKAL KEDAH.

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Presentation on theme: "2.0 ANALYSIS AND DESIGN 2.2 STRUCTURAL ELEMENT Reinforced Concrete Column Rearrangement by :- NOR AZAH BINTI AIZIZ KOLEJ MATRIKULASI TEKNIKAL KEDAH."— Presentation transcript:

1 2.0 ANALYSIS AND DESIGN 2.2 STRUCTURAL ELEMENT Reinforced Concrete Column Rearrangement by :- NOR AZAH BINTI AIZIZ KOLEJ MATRIKULASI TEKNIKAL KEDAH

2  Column is defined as a structural members subjected to compressive force.  Strut – a small compressive member in a framed structure.  Column – a larger member, such as the main support for a beam in a building. INTRODUCTION

3  Axially loaded compressive member can fail in two principal ways: -short fat member fail by crushing or splitting of the material. -long thin members fail by sideways buckling. INTRODUCTION

4 i) Braced column(tiang dirembat) – the lateral loads are resisted by wall or some other form of bracing ii) Unbraced column(tiang tidak dirembat) – the lateral loads are resisted by the bending of the column iii) Short Column (tiang pendek) ● l ex /h and l ey /b < 15 for a braced column ● l ex /h and l ey /b < 10 for an unbraced column iv) Slender(Long) Column ( tiang langsing) ● l ex l ey /b >15 for a braced column ● l ex l ey /b >10 for an unbraced column Types of column

5  Short column (p> pcr)usually fail by crushing when the material achieved its ultimate strength.  Slender column is liable to fail by buckling  The end moment on slender column cause it to deflect sideways exceed a critical values until the column buckles. Failure Mode

6  Slender Column - fails by sideways buckling - The load at which a slender column buckles, is known as its critical buckling load, P crit. P crit.= ΩEI / L 2 Where; E = Modulus of Elasticity I = second moment of area L = length between pins Failure Mode

7 Column detail

8 Longitudinal steel bar - A minimum of 4 bars is required in a rectangular column and 6 bars in a circular column. -The size of the bars should be not less than 10mm Links -Minimum size = ¼ x size of the largest compression bar but not less than 6mm -Maximum spacing = 12 x size of the smallest compression bar Reinforcement detail

9 Rectangular column Circular column Types of Reinforced Concrete Column

10 Load transfer on column for design

11 Factored Axial Load (N) for Column Design ● Interior Column – 1.25 ● Edge/face column – 1.5 ● Corner column – 2 Corner column Interior column Edge /face column

12 Short Axially Loaded Column Design Equation N = 0.4 f cu A conc +0.8 f y A sc Where N – Ultimate Axial load f cu – Characteristic of concrete strength A conc – area of concrete cross section f y – Characteristic of reinforcement strength A sc – area of reinforcement cross section N

13 Example: A column with 200 mm x 200 mm resists a factored axial load 500kN. Calculate the area of steel required if f y = 460 N/mm 2 and f cu = 30 N/mm 2 Table 1 Diameters and areas of reinforcing bars Bar dia.(mm) C/s area (mm 2 ) Table 1 Diameters and areas of reinforcing bars Bar dia.(mm) C/s area (mm 2 )

14 Formula for design column N = 0.4 f cu A conc f y A sc 500x10 3 = 0.4 (30) ( A sc ) (460) A sc = – 12 A sc A sc = A sc A sc = 56.18mm 2 A sc (for each bar) = 56.18mm 2 /4 = 14mm 2 A sc = Πj 2 = ΠD 2 /4=14mm 2 D = 14 x 4 / Π = 4.22mm Standard required 4 number of steel reinforcement bars size 10mm minimum). So size column = 4 T 10 4T10


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