Displacement Constraint Design in GT STRUDL

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Displacement Constraint Design in GT STRUDL

• Andrew S. Maham Dr. Kenneth M. Will
• CASE Center
• GTSUG 2003
• June 2003

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Presentation Outline

• Background Information
• Goals
• Solution Technique
• User Input Requirements
• Demonstration
• Future Enhancements
• Questions?

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Background Information

• What is Sensitivity Analysis?
• The method of determining the Best solution for
  satisfying a given constraint
• The Best solution will depend on the goal of the
  analysis
• Example Goals
• To limit displacements while minimizing weight
  increase
• To minimize weight while limiting displacement
  increases or meeting stress requirements

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Goals

• Provide a procedure for limiting displacements in
  a structure
• Attempt to quantify a users needs when using the
  procedure to limit displacements
• Supply an efficient, effective, and rational
  implementation plan for the procedure into
• GT STRUDL

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Solution Technique

• Goals of Sensitivity Analysis
• Limit structural displacements while minimizing
  structural weight increase
• Ways of achieving goals
• Alter member sizes
• Alter slab / shear wall thickness
• Alter compressive strength of concrete
• Alter structure geometry

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Member Displacement Sensitivity Coefficient
Definition
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Displacement Sensitivity Coefficient
Member i Strain Energy
Strain Energy Summation
Member i Change in Strain Energy
Member i Displacement Sensitivity Coefficient
How to select next size?
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Physical Member Sensitivity Coefficient
Physical Member Strain Energy
Physical Member Change in Strain Energy
Physical Member Displacement Sensitivity
Coefficient
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Member Selection Process

• Issues to keep in mind
• How to select Next largest member size?
• Next largest AX, IZ, or both?
• Program will initially select member based on
  next largest AX
• Negatives on diagonal of DK
• How will this affect sensitivity coefficients and
  constrained displacements?
• How will user be able to control member selection
  process?
• User-defined tables
• MEMBER CONSTRAINTS
• Symmetrical constraints

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Procedure Flow
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User Input Specifications

• Joint Displacement Constraints
• Member Information
• Member Updating Cycle Information
• Output Options

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User Input Specifications cont.

• New PARAMETERS
• CHGMEM
• Allow member changes Default YES
• Sample
• CHGMEM YES MEMBERS 1 to 10
• MAXCHGN or MAXCHGP
• MAXCHGN specifies number of members and MAXCHGP
  specifies percent of total members
• Sample
• MAXCHGN 5 ALL MEMBERS
• or
• MAXCHGP 0.1 ALL MEMBERS
• Default update members until all constraints are
  satisfied based on estimated displacement changes

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User Input Specifications cont.

• New PARAMETERS
• TBLNAM
• Specify table from which subsequent members will
  be selected
• Sample
• TBLNAM WBEAM9 MEMBERS 1 to 50
• MAXANALS
• Maximum number of structural analysis allowed
• Default 10
• Sample
• MAXANALS 15 ALL MEMBERS
• CHGTYPE
• Update most sensitive member for all (ALLCONS) or
  each (EACHCONS) constraint
• Sample
• CHGTYPE ALLCONS ALL MEMBERS

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User Input Specifications cont.

• New PARAMETERS
• DEFLCONX, DEFLCONY, DEFLCONZ
• Specifies constraint in either global X, Y, or Z
  direction at a joint
• Sample
• DEFLCONX 2.5 FOR JOINT 54
• DEFLCONZ -6.5 FOR JOINT 118
• No default
• LOADCONX, LOADCONY, LOADCONZ
• Specifies load(s) associated with a specified
  constraint at a joint in a global direction
• Sample
• LOADCONX 54 FOR LOADS Wind1 Wind2
• LOADCONZ 118 FOR LOADS EQ1
• No default

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Demonstration Overview

• Braced plane frame
• All parameters specified
• Minimal user input
• Unbraced plane frame
• Without MEMBER CONSTRAINTS
• With MEMBER CONSTRAINTS
• Braced space frame
• Effect of symmetric constraints

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General Example
Initial Member Properties (in.)
Profile AX IZ Beams W10x15 4.41
68.9 Columns W6x20 5.87 41.4 Braces
L4x4x3/8 2.859
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User Input
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Initial Program Output
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Final Iteration Output
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Display Constraint Information
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Display Results
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Display Summary of Results
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Display Summary of Results cont.
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Minimal User Input
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MEMBER CONSTRAINTS Example

Initial Member Properties TBLNAM
Profile Beams WBEAM9 W18x35 Columns
WCOLUMN9 W14x53
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MEMBER CONSTRAINTS Discussion

• Member Selection with Member Constraints
• Profile AX IZ
• Initial W18x35 10.3 510.0
• W16x36 10.6 448.0
• W14x38 11.2 385.0
• W10x39 11.5 209.0
• W8x40 11.7 146.0
• Final W18x40 11.8 612.0

MEMBER CONSTRAINTS 31 TO 54 CONSTRAIN 'ND' GE
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Initial User Input
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User Input with MEMBER CONSTRAINTS
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Symmetrical Structure Example
Unsymmetrical Constraint about plane of symmetry
Define Displacement constraint 'DEFLCONZ
-2.0 JOINT 119 'LOADCONZ 119'
LOADS WIND'
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Unsymmetrical Constraint Input
Define a Unsymmetrical constraint
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Unsymmetrical Member Changes
Updated Members
plane of symmetry
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Symmetrical Constraints
Symmetrical Constraint about plane of symmetry
Define Displacement constraints 'DEFLCONZ
-2.0 JOINT 119 'LOADCONZ 119'
LOADS WIND 'DEFLCONZ -2.0 JOINT 118
'LOADCONZ 118' LOADS WIND
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Symmetrical Constraints Input
Change updating type
Define a Symmetrical constraint
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Symmetrical Member Changes
Updated Members
plane of symmetry
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Future Enhancements

• Other member change options
• Finite element alterations
• Concrete strength increase
• Member size decrease
• Constraint specification options
• Column-line usage for interstory drift
  constraints
• Floor constraints specified by joint lists
• Loadings specified in same global direction

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Questions?