## Section Lightweight Concrete

11.1 General-------------------------------------------------------------11-1

11.3 Materials------------------------------------------------------------11-1

SECTION 1 SYMBOLS SECTION 1. SYMBOLS

For the purposes of this document, the following symbols apply. Note: the notation used is based on ISO 3898:1987

Latin upper case letters

A Accidental action

A Cross sectional area

Ac Cross sectional area of concrete

Ap Area of a prestressing tendon or tendons

As Cross sectional area of reinforcement

As,min minimum cross sectional area of reinforcement

Asw Cross sectional area of shear reinforcement

D Diameter of mandrel

DEd Fatigue damage factor

E Effect of action

Ec, Ec(28) Tangent modulus of elasticity of normal weight concrete at a stress of Oc = 0

and at 28 days

Ec,eff Effective modulus of elasticity of concrete

Ecd Design value of modulus of elasticity of concrete

Ecm Secant modulus of elasticity of concrete

Ec(t) Tangent modulus of elasticity of normal weight concrete at a stress of Oc = 0 and at time t

Ep Design value of modulus of elasticity of prestressing steel

Es Design value of modulus of elasticity of reinforcing steel

El Bending stiffness

EQU Static equilibrium

F Action

Fd Design value of an action

Fk Characteristic value of an action

Gk Characteristic permanent action l Second moment of area of concrete section

L Length

M Bending moment

MEd Design value of the applied internal bending moment

N Axial force

NEd Design value of the applied axial force (tension or compression)

P Prestressing force

Po Initial force at the active end of the tendon immediately after stressing

Qk Characteristic variable action

Qfat Characteristic fatigue load

R Resistance

S Internal forces and moments

S First moment of area

SLS Serviceability limit state

T Torsional moment

ÏEd Design value of the applied torsional moment

ULS Ultimate limit state

V Shear force

VEd Design value of the applied shear force Latin lower case letters

a |
Distance |

a |
Geometrical data |

Aa |
Deviation for geometrical data |

b |
Overall width of a cross-section, or actual flange width in a T or L beam |

bw |
Width of the web on T, I or L beams |

d |
Diameter; Depth |

d |
Effective depth of a cross-section |

dg |
Largest nominal maximum aggregate size |

e |
Eccentricity |

fc |
Compressive strength of concrete |

fcd |
Design value of concrete compressive strength |

fck |
Characteristic compressive cylinder strength of concrete at 28 days |

fcm |
Mean value of concrete cylinder compressive strength |

fctk |
Characteristic axial tensile strength of concrete |

fctm |
Mean value of axial tensile strength of concrete |

fp |
Tensile strength of prestressing steel |

fpk |
Characteristic tensile strength of prestressing steel |

fp0,1 |
0,1% proof-stress of prestressing steel |

fp0,lk |
Characteristic 0,1% proof-stress of prestressing steel |

fo,2k |
Characteristic 0,2% proof-stress of reinforcement |

ft |
Tensile strength of reinforcement |

ftk |
Characteristic tensile strength of reinforcement |

fy |
Yield strength of reinforcement |

fyd |
Design yield strength of reinforcement |

fyk |
Characteristic yield strength of reinforcement |

fywd |
Design yield of shear reinforcement |

h |
Height |

h |
Overall depth of a cross-section |

i |
Radius of gyration |

k |
Coefficient; Factor |

l (or l |
or L) Length; Span |

m |
Mass, reduced moment |

n |
reduced axial force |

r |
Radius |

1/r |
Curvature at a particular section |

t |
Thickness |

t |
Time being considered |

to |
The age of concrete at the time of loading |

u |
Perimeter of concrete cross-section, having area Ac |

u,v,w |
Components of the displacement of a point |

x |
Neutral axis depth |

x,y,z |
Coordinates |

z |
Lever arm of internal forces |

Greek lower case letters a Angle; ratio

P Angle; ratio; coefficient y Partial factor

Ya Partial factor for accidental actions A

yc Partial factor for concrete

Yf Partial factor for actions, F

YF,fat Partial factor for fatigue actions yc,fat Partial factor for fatigue of concrete

Yg Partial factor for permanent actions, G

Ym Partial factor for a material property, taking account of uncertainties in the material property itself, in geometric deviation and in the design model used

Yp Partial factor for actions associated with prestressing, P

Yq Partial factor for variable actions, Q

ys Partial factor for reinforcing or prestressing steel ys,fat Partial factor for reinforcing or prestressing steel under fatigue loading

Yf Partial factor for actions without taking account of model uncertainties

Yg Partial factor for permanent actions without taking account of model uncertainties

Ym Partial factors for a material property, taking account only of uncertainties in the material property

5 Increment/redistribution ratio

£ Reduction factor/distribution coefficient

£c Compressive strain in the concrete

£ci Compressive strain in the concrete at the peak stress fc

Ecu Ultimate compressive strain in the concrete

£u Strain of reinforcement or prestressing steel at maximum load

Euk Characteristic strain of reinforcement or prestressing steel at maximum load

### 0 Angle

X Slenderness ratio p. Coefficient of friction between the tendons and their ducts v Poisson's ratio v Strength reduction factor for concrete cracked in shear

Ratio of bond strength of prestressing and reinforcing steel p Oven-dry density of concrete in kg/m3

P1000 Value of relaxation loss (in %), at 1000 hours after tensioning and at a mean temperature of 20°C pl Reinforcement ratio for longitudinal reinforcement pw Reinforcement ratio for shear reinforcement CTc Compressive stress in the concrete

CTcp Compressive stress in the concrete from axial load or prestressing tfcu Compressive stress in the concrete at the ultimate compressive strain Ecu x Torsional shear stress

^ Diameter of a reinforcing bar or of a prestressing duct ^n Equivalent diameter of a bundle of reinforcing bars 9(t,fo) Creep coefficient, defining creep between times t and fa, related to elastic deformation at 28 days Final value of creep coefficient y Factors defining representative values of variable actions y 0 for combination values y i for frequent values y 2 for quasi-permanent values

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