4.14.2.3. Concrete02IS material¶

This command constructs a uniaxial concrete material with the same compressive envelope and tension/cyclic behavior as Concrete02, but with user-defined initial stiffness \(E_0\). In Concrete02 the initial stiffness is fixed at \(E_c = 2 f'_c / \varepsilon_{c0}\); Concrete02IS allows any \(E_0\) (for example \(57000\sqrt{f'_c}\) in psi units, or a secant stiffness to peak).

uniaxialMaterial('Concrete02IS', matTag, E0, fpc, epsc0, fpcu, epsU, *optional)¶: Optional trailing arguments (in order): ratio between unloading slope at epsU and initial slope, tensile strength ft, tension softening stiffness Ets.

Note

Compressive parameters are taken as negative; if given positive, they are converted internally. Input \(E_0\) affects unloading/reloading stiffness in compression. The ascending branch uses the Popovics equation (Concrete02 uses the Hognestad parabola).

Example

import openseespy.opensees as ops

fc, epsc0 = 4000.0, -0.002
fcu, epscu = -1000.0, -0.006
Ec = 2.0 * fc / (-epsc0)
ops.uniaxialMaterial('Concrete02IS', 1, Ec, fc, epsc0, fcu, epscu)
ops.uniaxialMaterial('Concrete02IS', 2, Ec, fc, epsc0, fcu, epscu, 0.1, 500.0, 1738.33)