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fmckenna edited this page Jan 2, 2018 · 8 revisions

MDOF (Multi-Degree of Freedom)

Tool Audience(Users):

Students taking course in structural dynamics, earthquake or wind engineering. Researchers/Practitioners trying to understand a building response

Tool Purpose:

This educational application allows the user to explore the effects of different building parameters on the time history response of a building subjected to earthquake, wind or other loadings that generate a transient response of the structure, i.e. time varying response.

The building itself is represented by a shear building model: an idealization of a structure in which the mass is lumped at the floor levels and the beams are assumed infinitely stiff in flexure and axially inextensible, and the columns are axially inextensible. The user inputs the floor weights and story properties (stiffness, yield strength, hardening ratio) of the stories, and a damping ratio for the elastic modes of vibration.

The user can quickly explore the effect of changing weight, height, and stiffness on the tine history response. In addition nonlinear effects due to P-Delta and soft story mechanisms can be studied.

Earthquake Excitation: For this input excitation the user can select from some existing ground accelerations or the user can add and select from their own motions. Internally the equations of motions are set up using the uniform excitation approach, i.e. MA + CV + KU = -MAg. A consequence of this approach is that the floor displacements solved for are relative displacements. These equations are solved using the Newmark constant acceleration method and Newton-Raphson solution algorithm.

Requirements:

A user group consisting of Professors teaching courses in dynamics, wind or earthquake engineering and graduate students who have previously taken such courses:

SimCenter members:Prof. Steve Mahin, Dr. Frank McKenna Non-SimCenter: Prof. Michael Scott (Oregon State Univeristy), Prof. Kevin Mackie (University of Central Florida)

The following are the main requirements identified.

  1. User able to modify properties of building and see effect on response:
  • Number of Floors
  • Building Height and Weight
  • Stiffness and Yield properties of Stories
  • Floor Masses
  • Optionally include PDelta effects
  1. User able to save current building properties into a file and subsequently load at any later instance in time.
  2. User able to view how response parameters change with time:
  • Floor displacements and story shear forces.
  1. User able to subject building to earthquake response:
  • User able to select from a range of ground motions stored as files on user system.
  • User able to scale motion magnitude.
  1. User able to subject building to harmonic excitation:
  • User able to vary magnitude and frequency of harmonic excitation
  1. User able to subject the building to wind loading
  • Wind loads from file on user system.
  1. User able to select from various base isolation models to see effect of base isolation on response of building.
  2. User able to add floor and interstory damper systems to building to see effects of dampers on response of building.
  3. User able to able to view modal quantaties for "elastic" building:
  • Modal participation and modal mass
  • Modal responses

Intended Users: Graduate Students/Researchers/Practicing Engineers.

Requirements for Building Tool

  1. User must install Qt
  2. User must download and place in source code directory qcustomplot.h and qcustomplot.cpp

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