Creep and Shrinkage in both Material and Cross-Section

API & Interfaces
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1

Dear Community,

I am currently struggling with defining creep and shrinkage properties via the RFEM 6 API, and I have encountered a few issues that I hope you can clarify:

  1. Time‑dependent properties appear in both the Material and Cross‑Section modules. Should both be used, or does one override the other?
  2. In the Material module, I can activate creep and shrinkage , but I cannot find any parameters for time development or relative humidity. Are these properties controlled elsewhere, or are they not accessible through the API?
  3. In the Cross‑Section module, most inputs are available , but when I run the script and check the model afterwards, the defined time value is still set to zero. Is this a known issue, or am I missing a required step in the API workflow?

Heres a snipped of the code



# Steel pile geometry
b = 0.5                                                     # Pile width [m]

# Quality
C_Q = "C30/37"

# Relative humidity
RH = 0.90
n_s = 100
t_max = 365*50


with rfem.Application() as rfem_app:
    rfem_app.close_all_models(save_changes=False)
    rfem_app.create_model(name="Påle_1")
    rfem_app.delete_all_objects()

    base_data: rfem.BaseData = rfem_app.get_base_data()


    material: rfem.structure_core.Material = rfem.structure_core.Material(
            no=1,
            time_dependent_properties_creep_enabled=True,
            time_dependent_properties_shrinkage_enabled=True,
            name=C_Q,
        )

    cross_section: rfem.structure_core.CrossSection = rfem.structure_core.CrossSection(
            no=1,
            material=1,
            type=rfem.structure_core.CrossSection.TYPE_PARAMETRIC_MASSIVE_I,
            parametrization_type=rfem.structure_core.CrossSection.PARAMETRIZATION_TYPE_PARAMETRIC_MASSIVE_I__MASSIVE_SQUARE__SQ_M1,
            b = b,
            rotation_angle=angle,
            advanced_time_dependent_properties_of_concrete_enabled=True,
            creep_enabled=True,
            shrinkage_enabled=True,
            relative_humidity=RH,
            function_data_function_type=rfem.structure_core.CrossSection.FUNCTION_DATA_FUNCTION_TYPE_SHRINKAGE_STRAIN_CA,
            function_data_number_of_steps=n_s,
            function_data_maximum_age_of_concrete=t_max,
        )

    rfem_app.create_object(material)
    rfem_app.create_object(cross_section)

Thanks in advance

3

Hi studentlnu11,

the best is to create a simple RFEM modell with the settings you want to achive. Then you can have a look at the settings and compare. This could also help: Generating Example Files for Using Objects in API (gRPC). Unfortunately not the whole modell is exported, but we're working on it.

If you cannot get it work, please send me a simple RFEM modell with all needed settings, and I'll have a deeper look into it.

Best regards
Robert Milrath

4

When I export the python file, the time dependant parts (creep and shrinkage) are not visible in the code. I get this for CS:

ERROR: Failed to export attributes: (advanced_time_dependent_properties_of_concrete_enabled: True), (creep_enabled: True), (shrinkage_enabled: True), (relative_humidity: 0.9), (function_data_function_type: "Creep Coefficient φ"), (function_data_maximum_age_of_concrete: 86400000), (function_data_number_of_steps: 100)

I resolved the last problem, the float value needs to be in seconds, I was entering the days..

I still dont understand why the time-dependent properties appear in both Materials and Cross-Section.

I will send you a file with the configurations

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