GSA 8'2 New Features

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GSA 8.2 New Features

• February 2007

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GSA 8.2Analysis Features
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GSA 8.2 Footfall Analysis

• Footfall analysis is to calculate the vertical
  responses (response factor, acceleration
  velocity etc) of floors or stairs subjected to
  the dynamic loads of human footfalls
• It is a serviceability limit state check to
  evaluate the disturbance level of the vibrations
  to humans or precision equipments in the
  buildings
• Both resonant and transient responses are
  calculated in GSA footfall analysis

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GSA 8.2 Footfall Analysis

• Options available in doing GSA footfall analysis
• Setting response and excitation nodes separately
• Three damping options constant, from modal
  analysis and user defined damping for individual
  modes
• Body weight of the walker
• Method to calculate footfall loads - Arup or SCI
  method
• Range of walking frequency

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GSA 8.2 Footfall Analysis

• Footfall is considered as periodic loads and it
  is decomposed into a number of harmonic loads,
  e.g.
• f(t)
• f1 sin(?0tf1) f2 sin(2?0tf2) f3
  sin(3?0tf3) f4 sin(4?0tf4)
• Footfall analysis is carried out for each of the
  harmonic components of footfall loads using
  harmonic analysis and adding the responses from
  each of the harmonic analyses using square root
  of the sum of square method to get the total
  response from the footfall

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GSA 8.2 Footfall Analysis

• Evaluation of footfall responses
• Human perception to acceleration is not the same
  for the same acceleration level, it varies with
  the forcing frequencies
• The most sensitive frequencies to human are from
  4 to 8 Hz
• It is logical to use a dimensionless parameter
  response factor rather than the absolute
  acceleration to determine the disturbance level
  to humans
• A general indication of human perception to
  acceleration is shown on the right

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GSA 8.2 Footfall Analysis

• Response factor is the ratio of the calculated
  responses to the base response curve (the base
  response curve for acceleration is shown on
  right)
• Response factor is used to evaluate the
  disturbance level to human by the footfall loads

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GSA 8.2 Footfall Analysis

• Outputs of footfall analysis
• Maximum response factor
• Peak acceleration
• Peak velocity
• RMS and RMQ velocity
• Critical walking location (node) and critical
  walking frequency
• Participation factor
• Outputs can be viewed on
• Contour
• Diagram
• Table
• Chart View (new output in 8.2)

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GSA 8.2 Footfall Analysis

• Doing footfall analysis in GSA
• Footfall analysis utilises modal dynamic analysis
  results such as natural frequencies and mode
  shapes etc
• The construction of GSA model for footfall
  analysis is the same as that for modal analysis.
  To make sure that there are enough vertical
  vibration modes in modal analysis, a sub-model
  may be used for footfall analysis
• Footfall analysis is to evaluate the vertical
  responses, so it is very common to just model a
  single floor with horizontal constraints to
  activate the vertical vibration modes
• The modal analysis used for footfall analysis
  should cover all the vertical modes with
  frequencies up to 15 Hz

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GSA 8.2 Footfall Analysis floor response
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GSA 8.2 Footfall Analysis stair response
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GSA Footfall Analysis examples of chart views
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GSA 8.2 Harmonic Analysis

• Harmonic analysis is to calculate the structural
  responses at steady state under harmonic loads
• Harmonic load is any load that its magnitude
  varies according to sine or cosine curves
• Outputs from harmonic analysis are the peak
  values of displacements, velocities,
  accelerations, forces and moments etc.
• A range of harmonic load frequencies can be given
  in a harmonic analysis, so the critical harmonic
  frequency can be determined from the analysis
  results

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GSA 8.2 Non-linear spring element

• Available for GSA non-linear analysis solver
  GsRelax
• The non-linear behaviour of the spring element is
  defined by non-linear spring curves in terms of
  force displacement or moment rotation
• Tension and compression curves can be different

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GSA 8.2 Sparse Solver

• New GSS solver option
• Allows much larger models to be analysed than the
  traditional active column solver
• Appropriate for all GSS analysis options
• Sparse storage technique is less memory hungry,
• - but not as memory efficient as the conjugate
  gradient solver.
• Direct solution, so no convergence issues.

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GSA 8.2 Sparse Solver setting
Click Advanced on the last page of the
Analysis Wizard to get to
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GSA 8.2 Constraint Equations

• Allow constraint to be applied to a node (the
  slave) as a function of the displacement of other
  nodes (the masters).
• Constraint equations generalise the constraint
  types in GSA Restraints, Settlements, Joints,
  Rigid Constraints.
• General form

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GSA 8.2 Constraint Equation input
Node 11 will be forced to move in the x direction
by the average of the node 10 and 12 x
translation.
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GSA 8.2Links with 3D Modelling CAD Packages
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GSA 8.2 Revit Structure link

• GsRevit is a Revit Structure plug-in
• The following options are offered from within
  Revit
• Export from Revit to GSA
• Update Revit model from GSA model
• Import from GSA to Revit
• (Uses GSA COM interface to communicate directly
  with GSA)

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GSA 8.2 GsRevit Export to GSA

• Export selection or whole model
• Export to design layer (members areas) or
  analysis layer (elements)
• Design layer better Revit objects are more like
  members
• Export all properties or only referenced
• All is recommended allows different Revit
  property to be selected in GSA
• Allows sync with previously exported GSA model
• Extra data is not overwritten
• Export log reports errors and uncertainties

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GSA 8.2 GsRevit Update from GSA

• Updates Revit model with changes made in GSA
• Only works with GSA models that were originally
  exported from the Revit model
• Recognises changes to
• Levels (grid plane elevations)
• Column and beam positions
• Column and beam property references
• Logs changes that cannot be translated

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GSA 8.2 GsRevit Import from GSA

• Creates new Revit model from GSA model
• Import from Design layer or Analysis layer
• Import from saved GSA lists
• Import grid planes as levels
• Import catalogue sections as Family types
• User option to manually assign equivalent Family
  types from GSA sections

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GSA 8.2 Revit Model
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GSA 8.2 GsRevit Export interface
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GSA 8.2 GsRevit Export log
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GSA 8.2 GsRevit GSA model
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GSA 8.2 GsRevit Update interface
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GSA 8.2 GSA Model
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GSA 8.2 GsRevit Import interface
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GSA 8.2 Model imported into Revit
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GSA 8.2 GsRevit status

• RS4 is the current version of Revit Structure
• GSA 8.2 is compatible with RS4 and RS3
• RS5 is released at alpha status (Jan 2007)
• RS5 compatibility is scheduled for a GSA 8.2
  rebuild

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GSA 8.2 CAD Import/Export Enhancements

• Improvements to existing import/export facility
• Works with either DWG or DXF file
• Compatible with latest versions of AutoCAD
• More control over import
• Control over mapping of layers to properties
• Suggestion of model units
• Option to connect 1D elements
• Option to offset beams from columns
• align with top
• move to face
• Control of tolerances

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GSA 8.2 CAD Import
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GSA 8.2 CAD Import
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GSA 8.2 CAD Export
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GSA 8.2The GSA Modelling Platform
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GSA 8.2 Revised Grids

• Grid lines, grid layouts and grid planes are now
  independent.
• Grid lines are specified explicitly and,
  implicitly, lie in the global XY plane,
• - but are displayed projected on to the current
  grid plane.
• Better platform for receiving third party 3D
  model data.

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GSA 8.2 Revised Grids
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GSA 8.2 Revised Grids
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GSA 8.2 Revised Grids
Grid Lines projected on to current grid
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GSA 8.2 New Geometric Entities

• Geometric entities
• Grid Nodes, Lines, Areas, Regions
• For the representation of slabs and walls
• Specified on the Design Layer
• Grid Nodes are ordinary nodes that can be located
  with respect to Grid Line intersections
• Geometric entities include 2D mesh generation
  attributes

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GSA 8.2 New Geometric Entities
Adding Grid Nodes and Lines at intersection of
Grid Lines
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GSA 8.2 New Geometric Entities
Lines bounding an Area
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GSA 8.2 New Geometric Entities
A Region with bounding Area, an internal void
Area and Grid Nodes.
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GSA 8.2 - Improved 2D Element Meshing

• New, more powerful mesh generator
• Mesh now generated from Regions that are made up
  of Areas, Lines and Grid Nodes
• Mesher can pick up internal points (e.g. columns)
  and include these in the mesh
• More control over elements per side, element
  spacing,

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GSA 8.2 Region prepared for meshing
A Region with adjacent bounding Areas, internal
Grid Nodes, Lines and Areas, one of which is void.
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GSA 8.2 the meshed region
The resulting mesh takes into account the
internal Grid Nodes, Lines and Areas.
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GSA 8.2Miscellaneous new features
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GSA 8.2 Element snap
When adding elements you can snap to another
element.
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GSA 8.2 Ambiguous selection, properties
When toggling through the ambiguous selection
options the properties of the current item are
displayed.
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