Check by calculation

10.2.3.1 Calculation of steel stress and strain

Steel stress:

c ct.eff ct

where

A = area of reinforcement within the tensile zone k =

^ct.eff

Therefore area of concrete within tensile zone 1000 x 200 = 200 x 103 mm2 a coefficient taking account of stress distribution 1.0 for pure tension a coefficient allowing for the effect of non-uniform self-equilibrating stresses

0.8 for tensile stresses due to restraint of intrinsic deformations (h < 300 mm)

tensile strength of concrete effective at first cracking 3.8 N/mm2 (taking fctk Q95 but see Section 10.2.3.4)

Mean strain:

^sm where E

Therefore e =

modulus of elasticity of steel 200 kN/mm2

a coefficient taking account of bond properties of the bars 1.0 for high bond bars a coefficient taking account of load duration 0.5

the stress in the reinforcement based on a cracked section under the load causing first cracking a for intrinsic imposed deformation

0 0

Post a comment