Fyd Desin Ield Strength Of Longitudinal Reinforcement

Characteristic tensile strength of prestressing steel

'yld

ywk fRdu Design value of ultimate bearing stress fs Stress in reinforcement ft Stress in concrete at top fibre fyd Design yield strength of reinforcement fyk Characteristic yield strength of reinforcement

Design yield strength of longitudinal torsion reinforcement Design yield strength of shear reinforcement or torsion links Characteristic yield strength of shear reinforcement or torsion links gk Characteristic dead load per unit area h Overall depth of section or liquid in tank h' Reduced value of h for separate check about minor axis of column section with biaxial eccentricities ha Active height of deep beam hc Overall depth of corbel at face of support

/j, Overall depth of flange hH Depth of column head

/imax Larger dimension of rectangular section hmin Smaller dimension of rectangular section hu Total height of structure in metres

/' Radius of gyration of section k Coefficient or factor

/fA Restraint coefficient at end A

kB Restraint coefficient at end B

'Wm Restraint coefficient at bottom kc Minimum reinforcement coefficient associated with stress distribution klop Restraint coefficient at top k, Crack spacing coefficient associated with bond characteristics k2 Crack spacing coefficient associated with strain distribution

I Length or span

V Length of tendon over which anchorage slip is taken up lb Basic anchorage length

'b.min Minimum anchorage length

/bnet Required anchorage length lc Diameter of circular column

/col Height of column between centres of restraints le„ Effective span

'eff.siab Effective span of slab

/H Distance from column face to edge of column head ln Clear distance between faces of support

I Distance between positions of zero bending or effective height of column ° or, for deep beams, clear distance between faces of support

/ Length of compression flange between lateral supports

/ Required lap length or floor to ceiling height in metres

I Minimum lap length s.min n ^

Greater of distances in metres between centres of columns, frames or walls supporting any two adjacent floor spans in direction of tie under consideration

Z Effective span in x direction

I Effective span in y direction

/ / Lengths between centres of supports or overall dimensions of rectangular column head mSd Minimum design moment per unit width n Ultimate design load per unit area or number of tendons or number of sub-divisions p' Average loss of prestressing force per unit length due to friction q Equivalent load per unit length due to prestressing force profile gk Characteristic imposed load per unit area r Radius of bend or radius of curvature rx Radius of curvature based on uncracked section rn Radius of curvature based on cracked section rcs Radius of curvature due to concrete shrinkage rcsI Radius of curvature due to concrete shrinkage based on uncracked section r Radius of curvature due to concrete shrinkage based on cracked section r Total radius of curvature s Spacing of shear reinforcement or torsion links or horizontal length of tendon profile sf Spacing of transverse reinforcement within flange of beam smax Maximum spacing of shear reinforcement or torsion links srm Average final crack spacing t Thickness of supporting element or wall of thin-walled section t . Minimum thickness of wall min u Circumference of concrete section or critical section for punching shear uk Circumference of area /4k vRd1 Design shear resistance per unit length of critical perimeter, for slab without shear reinforcement vRd2 Maximum design shear resistance per unit length of critical perimeter, for slab with shear reinforcement

\/Rcl3 Design shear resistance per unit length of critical perimeter, for slab with shear reinforcement vSd Design value of shear force per unit length of critical perimeter w Support width or quasi-permanent load per unit length wk Design crack width wmm Minimum width of support x Neutral axis depth or distance along span from face of support or distance along tendon or column dimension in x direction x' Maximum depth of concrete in compression in direction of minor axis for column section with biaxial eccentricities xc Depth of concrete in compression at position of minor axis for column section with biaxial eccentricities y Drape of tendon at distance x along profile or column dimension in y direction yt Distance from centroid of uncracked section to extreme tension fibre z Lever arm of internal forces zcp Distance from centroid of section to centroid of tendons a Reduction factor for concrete compressive stress or modular ratio or deformation parameter a, Value of parameter based on uncracked section au Value of parameter based on cracked section aa Effectiveness coefficient for anchorage ae Effective modular ratio an Reduction coefficient for assumed inclination of structure due to imperfections

"sx'^sy foment coefficients in x and y directions a1 Effectiveness coefficient for lap j3 Coefficient with several applications including shear resistance enhancement, effective height of column, St Venant torsional stiffness, punching shear magnification, design crack width

/3red Reduced value of shear resistance enhancement coefficient

|81 Coefficient associated with bond characteristics

/32 Coefficient associated with duration of load

7C Partial safety factor for concrete material properties

7f Partial safety factor for actions

7G Partial safety factor for permanent action or dead load

■Vc ini Partial safety factor for permanent action, in calculating lower design value

?g,sup Partial safety factor for permanent action, in calculating upper design value

7P Partial safety factor for actions associated with prestressing force

7q Partial safety factor for variable action or imposed load

7S Partial safety factor for steel material properties of reinforcement or prestressing tendons

5 Ratio of redistributed moment to moment before redistribution eb Strain in concrete at bottom of section ecs Basic concrete shrinkage strain ecs« Final concrete shrinkage strain ep Minimum strain in tendons to achieve design tensile strength epm Strain in tendons corresponding to prestressing force P

es

Strain in reinforcement

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