5.2 Analysis methods 5.2.1 Basic assumptions .Plane cross section remain plane during bending(Bernoulli assumption) .There is full bond between concrete and steel .Concrete behavior in the compressive zone is described by an uniaxial stress-strain curve .The tensile strength of concrete is ignored .The behavior of steel is described by the stress-strain curves for steel in compression or tension .Failure accurse when the strain of concrete of the extreme compressive fiber attains a critical value su usually taken to be equal to 0.00335.2 Analysis methods • 5.2.1 Basic assumptions •Plane cross section remain plane during bending (Bernoulli assumption) •There is full bond between concrete and steel •Concrete behavior in the compressive zone is described by an uniaxial stress-strain curve •The tensile strength of concrete is ignored •The behavior of steel is described by the stress-strain curves for steel in compression or tension •Failure accurse when the strain of concrete of the extreme compressive fiber attains a critical value εu usually taken to be equal to 0.0033