.. _atr_human_induced_vibrations-label:

===============================
Human induced vibrations module
===============================
This module contains functionality for analyses of human induced vibrations.

Step walking load analysis
==========================
In structural engineering, a step walking load analysis is used to understand and predict the impact of pedestrian
traffic on structures like floors, bridges, and walkways. The procedure for the determination of an acceptable floor
response to excitation induced by walking persons is based on the following:

1. The characteristics of the loading by identifying the appropriate features of the walking process by describing the
   load-time-history as a function of body weight, step frequency and their statistical demographic distribution,
2. The identification of the dynamic floor response from representative 'Single degree of freedom'-models for different
   typologies of floors, to which actions in the form of parameterized time-histories of step forces are applied; these
   responses are given as time-histories or frequency distributions for further evaluations,
3. The comfort assessment of the floor responses taking into account human perception and condensation of data to a
   single representative response parameter (OS-RMS-value90) which defines a certain fractile of the distribution of
   responses to actions and is suitable for being compared with response requirements depending on the type of building
   and its use.

For more background information refer to [1]_ and [2]_.

.. note:: Current functionality provides tools for the first item, providing for the characteristics of the loading.

You can use the functionality by importing the human induced vibrations module:

.. code-block:: python

    from haskoning_atr_tools.human_induced_vibrations import *

References
----------
.. rubric:: References

.. [1] `Trillingen van vloeren door lopen Richtlijn voor het voorspellen, meten en beoordelen, SBR, d.d.
       September 2005 <https://corporateroot.sharepoint.com/:b:/s/Knowledge-GroupIBStructuralDesign/EbwZyct2frpBkQg9ffIKiikBvbKEkFz9L6XlnlxiYBIJOA?e=doW4Xm>`_
.. [2] **Background Document for Floor Vibrations** RFS2-CT-2007-00033, Hivoss, d.d. 2007

Calculate the walking load
==========================
The walking load can be created with the 
:py:func:`~haskoning_atr_tools.human_induced_vibrations.walking_load.calculate_walking_load` function:

.. code-block:: python

    walking_load = calculate_walking_load(step_frequency=2.0, body_mass=70, nr_steps=20, load_reduction=True)

=======================  =====  ========================================================================================
step_frequency           float  The frequency of the steps, in [Hz]. The frequency should be between 1.64 and 3Hz.
body_mass                float  The mass of the body, in [kg]. The body mass should be between 40 and 125kg.
nr_steps                 int    The number of steps to apply in the walking load.
load_reduction           bool   Toggle to apply a load reduction is applied to the first four and last four steps.
                                Default value is False
=======================  =====  ========================================================================================

Plot
----
The walking load can be visualised with the plot
:py:meth:`~haskoning_atr_tools.human_induced_vibrations.step_walking_load.StepWalkingLoad.plot` method.

.. code-block:: python

    walking_load.plot()

.. figure:: _static/walking_load.png
    :align:   center

    Generated plot of the walking load over time.

Also a plot can be generated for the load of a single step.

.. code-block:: python

    walking_load.step_load.plot()

.. figure:: _static/step_load.png
    :align:   center

    Generated plot of a single step over time.

Conversion to FEM
-----------------
A method is available to convert the walking load to an instance of the Timeseries class in the haskoning_structural
package. This object can be used in structural engineering software to analyse the walking load. To apply this
functionality the user should install the haskoning_structural module separately as it does not come standard with the
ATR tools module.

.. code-block:: python

    timeseries = walking_load.to_fem(project=fem_project)

Reference
---------

.. automodule:: haskoning_atr_tools.human_induced_vibrations.walking_load
   :members: calculate_walking_load

StepLoad class
==============
The StepLoad class represents the load generated by a single walking step.

Reference
---------
This is the documentation of the class and methods of StepLoad:

.. autoclass:: haskoning_atr_tools.human_induced_vibrations.step_load.StepLoad
   :members:

   .. automethod:: __init__

StepWalkingLoad class
=====================
The StepWalkingLoad class represents the load generated by a series of walking steps.

Reference
---------
This is the documentation of the class and methods of StepWalkingLoad:

.. autoclass:: haskoning_atr_tools.human_induced_vibrations.step_walking_load.StepWalkingLoad
   :members:

   .. automethod:: __init__