9.4.2 User-supplied

Application of the Modified Maekawa model via a user-supplied subroutine is only useful of you want to change the model with respect to the standard implementation in the DIANA code, for instance to perform some scientific experiments. Application of the standard code of subroutine USRMNL, as supplied in the DIANA distribution,^9.3is equivalent to application via direct input.

    (syntax)

YOUNG

e is the Young's modulus E .

POISON

nu is the Poisson's ratio $\nu$ .

CRACKB

h is the crack bandwidth h .

RECLOS

activates the crack-reclosing option [§22.3].

USRMAT

MAEKAW indicates that the Maekawa concrete model must be applied via user-supplied subroutine USRMNL [§11.3.10].

USRVAL

are four parameters which will be passed to subroutine USRMNL via argument USRVAL.

fc

is the compressive strength f_c .

ft

is the tensile strength f_t .

gf1

is the fracture energy G_f^I for Mode-I.

b

is the correction factor b for plastic evolution ... (22.3).

USRSTA

is one parameter which will be passed to subroutine USRMNL via argument USRSTA.

fract

is the initial value of the fracture parameter K . You are advised to set this value to 1. With ongoing deformation this parameter will gradually reduce to zero.

USRIND

are two parameters to indicate the material models to be applied. These parameters will be passed to subroutine USRMNL via argument USRIND.

soften

indicates the softening model to be applied.

1

for linear softening [Fig.9.13c].

2

for multi-linear softening [Fig.9.13f]. This also requires the input of the multi-linear diagram via the TENPAR input item [§9.4.1].

3

for exponential softening [Fig.9.13d].

5

for Hordijk softening [Fig.9.13e].

13

for user-defined softening. This also requires the code of user-supplied subroutine USRCRV [§11.3.1].

14

for ideal softening [Fig.9.13a].

15

for brittle softening [Fig.9.13b].

crackm

indicates the crack model to be applied.

1

for the Total Strain Rotating crack model [§18.2.1].

2

for the Total Strain Fixed crack model [§18.2.1].

3

for the Total Strain Non-ortogonal crack model [§22.4].

SHRCRV

curve is the name of the shear retention function [§9.4.1.2]. The shear retention parameters are specific for the applied function.