Upload
brennen-crowther
View
226
Download
0
Tags:
Embed Size (px)
Citation preview
Project #4 Energy Dissipation Capacity of a Wood-frame Shear Wall
CEE 3702 - Numerical Analysis
Session Objectives
• Provide background on the performance of wood-frame structures subjected to earthquakes (Northridge)
• Provide the specifics of an experimental research program aimed at reducing damage
• Define the scope of the numerical analysis project
Historical Performance of Wood-Framed Structures Under Seismic Loads
• Properly designed and constructed structures perform “adequately”
• Significant secondary damage to structures following an earthquake
• Catastrophic failures in non-engineered or poorly constructed structures
Performance of Wood-frame Structures in the Northridge Earthquake, January 17, 1994
• 19 deaths
• Collapse of Hillside and Tuck-Under Parking
• $40 billion loss (primarily due to secondary damage)
Northridge Ground Motion
Ground Damage
Ground Damage
Structural vs. Nonstructural Damage
• Structural Systems– Beams
– Columns
– Slabs
– Steel, Concrete, Masonry, Wood
What is nonstructural damage?
Nonstructural Damage
• All damage that is not structural
• Secondary damage
• More costly than structural damage
• Includes nonphysical damage
Window Frames
Elevator and Door Frames
Collapse
Cripple Walls
Typical Wood Shear Wall
Wood-frame Shear Walls
Wood-frame Shear Walls
Wall Openings
Anchor Bolts
• Quantity and Location
• Splitting of Bottom Plate
• Splitting of Posts
• Construction/Installation Errors
Anchor Bolts
Nonstructural Damage
Problems in Wood Structures
• Cripple Walls
• Shear Walls
• Wall Openings
• Anchor Bolts
• Nonstructural Damage
How do we improve these trouble areas?
Northridge Fallout
• City of Los Angeles Inspections• Code Changes (after every EQ)
• Research - $6.9 million from FEMA to CUREe (California Universities for Research in Earthquake Engineering)
• Innovative Systems
Improvements
• Strong Walls
• Anchor Bolts
• Add Strength
Objective of the Experimental Research Program
• Investigate and evaluate methods for increasing the energy dissipation capacity of wood-framed shear walls using viscoelastic dampers.
Viscoelastic Dampers
• Viscoelastic dampers manufactured by 3M
• Prevalent in Steel and Concrete Structures
* Never been applied to wood-frame structures
Damping Schemes
• Corner
• Sheathing-to-stud
• Diagonal
• X-brace
VE Dampers Applied to Wood Walls
Dynamic Test Setup
Wood Shear Wall
Hydraulic Actuator applying the “EQ”
Experimental Investigation
• Full-scale testing of conventional wood shear walls (no dampers)
• Full-scale testing of wood shear walls with viscoelastic dampers
• Compare structural properties of both
Dynamic Test Procedure
Displacement (in)
-3 -2 -1 0 1 2 3
Loa
d (l
b)
-10000
-8000
-6000
-4000
-2000
0
2000
4000
6000
8000
10000
Typical Results
Calculation of KE and ED
-400
-300
-200
-100
0
100
200
300
400
-0.015 -0.01 -0.005 0 0.005 0.01 0.015
Displacement (in)
Loa
d (l
b)
KE
ED
Numerical Analysis Project
• The data for two individual hysteresis loops is on the website.– 1 set for a conventional wall– 1 set for a diagonally damped wall
• Calculate the energy dissipation for each wall• Determine whether or not using VE dampers as a
means for increasing the energy dissipation capacity of wood-frame shear walls is feasible.
Final Project
• Executive Summary
• Problem Description
• Detailed Solution Methodology
• Results
• Conclusions
Project Due at the beginning of class
on Monday December 11th