Hi valpat,
Below is a simple code snippet to demonstrate the basic workflow for Modal analysis via the Dlubal API. This should already cover what you need in terms of Modal analysis and getting effective modal masses per mode shape.
Regarding the Response Spectrum, there is still some work to do, so let us know what specifically you need in this area to clarify it in detail.
from dlubal.api import rfem, common
from math import inf
def initialize_model():
# Create new empty model
rfem_app.close_all_models(save_changes=False)
rfem_app.create_model(name="Modal Analysis")
# Set global model settings:
base_data: rfem.BaseData = rfem_app.get_base_data()
# Activate add-ons
base_data.addons.modal_analysis_active = True
# Set standard
base_data.standards.dynamic_analysis_standard = rfem.BaseData.Standards.DYNAMIC_ANALYSIS_NATIONAL_ANNEX_AND_EDITION_EN_1998_1_DIN_2023_11_STANDARD
# Adjust general settings
base_data.general_settings.gravitational_acceleration = 9.81
# Activate combination wizard
base_data.combinations_settings.combination_wizard_active = True
rfem_app.set_base_data(base_data=base_data)
rfem_app.delete_all_objects()
def create_structure():
structure = [
# Material
rfem.structure_core.Material(
no=1,
name="S235 | EN 1993-1-1:2005-05",
),
# Section
rfem.structure_core.Section(
no=1,
name="IPE 550 | DIN 1025-5:1994-03 | Ferona",
material=1,
),
# Nodes
rfem.structure_core.Node(
no=1,
coordinate_2=-2,
),
rfem.structure_core.Node(
no=2,
coordinate_2=-2,
coordinate_3=-4,
),
# Line
rfem.structure_core.Line(
no=1,
definition_nodes=[1, 2],
),
# Member
rfem.structure_core.Member(
no=1,
line=1,
section_start=1,
),
# Support
rfem.types_for_nodes.NodalSupport(
no=1,
user_defined_name_enabled=True,
name="Fixed",
nodes=[1],
spring=common.Vector3d(x=inf, y=inf, z=inf),
rotational_restraint=common.Vector3d(x=inf, y=inf, z=inf),
)
]
rfem_app.create_object_list(structure)
def create_loading():
loading = [
# Load Case | LC1
rfem.loading.LoadCase(
no=1,
name="Static | Self-weight",
static_analysis_settings=1,
),
# Nodal Loads | LC1
rfem.loads.NodalLoad( # Force
no=1,
nodes=[2],
force_magnitude=1000,
load_direction=rfem.loads.NodalLoad.LOAD_DIRECTION_GLOBAL_Z_OR_USER_DEFINED_W_TRUE_LENGTH,
load_case=1,
),
rfem.loads.NodalLoad( # Mass
no=2,
load_type=rfem.loads.NodalLoad.LOAD_TYPE_MASS,
nodes=[2],
individual_mass_components=True,
mass=common.Vector3d(x=100, y=100, z=100),
mass_moment_of_inertia=common.Vector3d(x=100, y=100, z=100),
load_case=1,
),
# Static Analysis Settings
rfem.loading.StaticAnalysisSettings(
no=1,
analysis_type=rfem.loading.StaticAnalysisSettings.ANALYSIS_TYPE_SECOND_ORDER_P_DELTA,
mass_conversion_enabled=True,
),
# --- Combinatoric for Seismic Mass ---
# Combination Wizard
rfem.loading.CombinationWizard(
no=1,
static_analysis_settings=1,
consider_imperfection_case=True,
),
# Design Situations
rfem.loading.DesignSituation(
no=1,
name="Seismic/Mass Combination - psi-E,i",
design_situation_type=rfem.loading.DesignSituation.DESIGN_SITUATION_TYPE_SEISMIC_MASS,
combination_wizard=1,
),
]
rfem_app.create_object_list(loading)
def define_modal_analysis_cases():
modal_analysis = [
# Modal Analysis Settings
rfem.loading.ModalAnalysisSettings(
no=1,
name='User-defined | Mode=2',
user_defined_name_enabled=True,
acting_masses_about_axis_x_enabled=False,
acting_masses_about_axis_y_enabled=False,
acting_masses_about_axis_z_enabled=False,
acting_masses_in_direction_z_enabled=False,
activate_minimum_initial_prestress=True,
solution_method=rfem.loading.ModalAnalysisSettings.SOLUTION_METHOD_ROOT_OF_CHARACTERISTIC_POLYNOMIAL,
number_of_modes=2,
),
rfem.loading.ModalAnalysisSettings(
no=2,
name='Automated | Mass=95%',
user_defined_name_enabled=True,
acting_masses_about_axis_x_enabled=False,
acting_masses_about_axis_y_enabled=False,
acting_masses_about_axis_z_enabled=False,
acting_masses_in_direction_z_enabled=False,
activate_minimum_initial_prestress=True,
solution_method=rfem.loading.ModalAnalysisSettings.SOLUTION_METHOD_ROOT_OF_CHARACTERISTIC_POLYNOMIAL,
number_of_modes_method=rfem.loading.ModalAnalysisSettings.NUMBER_OF_MODES_METHOD_EFFECTIVE_MASS_FACTORS,
effective_modal_mass_factor=0.95
),
# Modal Load Cases
rfem.loading.LoadCase(
no=2,
analysis_type=rfem.loading.LoadCase.ANALYSIS_TYPE_MODAL_ANALYSIS,
name="Modal | Self-mass",
modal_analysis_settings=1,
),
rfem.loading.LoadCase(
no=3,
analysis_type=rfem.loading.LoadCase.ANALYSIS_TYPE_MODAL_ANALYSIS,
name="Modal | Mass=95%",
modal_analysis_settings=2,
),
]
rfem_app.create_object_list(modal_analysis)
def import_masses_to_cases():
rfem_app.generate_combinations()
object_list = rfem_app.get_object_list(
objs=[rfem.loading.LoadCase()]
)
for obj in object_list:
lc: rfem.loading.LoadCase = obj
if lc.analysis_type is rfem.loading.LoadCase.ANALYSIS_TYPE_MODAL_ANALYSIS:
lc.import_masses_from.no = 1
lc.import_masses_from.object_type = rfem.ObjectType.OBJECT_TYPE_LOAD_COMBINATION
rfem_app.update_object_list(object_list)
def get_effective_modal_masses():
rfem_app.calculate_all(skip_warnings=True)
results = rfem_app.get_results(
results_type=rfem.results.ResultsType.MODAL_ANALYSIS_EFFECTIVE_MODAL_MASSES
)
print(f"\nEffective Modal Masses:\n{results.data}")
with rfem.Application() as rfem_app:
# Modal Analysis Procedure
initialize_model() # Activate add-on, ...
create_structure() # Column IPE 550 (fixed)
create_loading() # Force + Mass
define_modal_analysis_cases() # Self-mass (Mode=2) | Mass=95% (Mode=auto)
import_masses_to_cases() # Import masses from generated combination
get_effective_modal_masses() # Calculation + reading results
Hope this helps! Let me know if you need any further clarification or if you'd like additional information in this area.
