BUILDING PERFORMANCE

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BUILDING PERFORMANCE
Bob Leicester (CSIRO, Melbourne, Australia)
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STRUCTURAL TIMBER
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Local slope of grain
Juvenile wood
knot
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Adelaide Golf Club-house (2003)
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In-grade measurements
10,000 specimens (all properties)
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Total population of timber
frequency
strength
Design strengths
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ELECTRONIC SCANNING
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CSIRO MICROWAVE SCANNER
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SINGLE PARAMETER GRADING (Grading for stress
grades)
High strength and stiffness
Data points
Tension strength
beam stiffness
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MULTIPLE PARAMETER GRADING (Grading for
products)
high strength
floor joists
high stiffness
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Value Adding
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A Philippines sawmill
Logs and lumber are stacked according to country
of origin and not by species.
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SAMPLING PROGRAM

• number of mills 8
• number of species 52

Tropical hardwoods
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Graded Green, Tested Dry
120
4.74
6.60
8.46
10.31
12.17
M25
M20
M15
M10
100
M5
80
Bending Strength (MPa)
60
40
20
0
0
1
2
3
4
5
6
7
8
9
10
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13
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Grading Modulus (GPa)
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ENGINEERED WOOD PRODUCTS
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Laminated Veneer Lumber
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Parallam
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Used in 80 of new housing in USA
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PERFORMANCE
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BUILDING FIRES
Prior to 1994, combustible materials were not
permitted in fire-separation walls between
occupancies
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Not permitted
SOU single occupancy unit
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FURNITURE TEST
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ROOM BURN
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SOME COMPONENTS OF A RISK MODEL

• fire growth
• occupant warning
• fire brigade response
• evacuation
• smoke hazard

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Concrete construction

• warning systems . ..NO
• sprinkler systems .. NO

Relative risk to life 1.00
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Permitted
SOU single occupancy unit
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BUSHFIRE
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• Cause of destruction
• from radiation 10
• from ember attack 90

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50m from forest front
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ENGINEERED DURABILITY
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Sphaeroma
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HAZARDS

• decay fungi
• mould
• termites
• marine borers
• corrosion of connectors

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INPUT PARAMETERS
BUILDING PERFORMANCE

• building
• location
• hazard
• maintenance

• Collapse
• serviceability
• appearance

ATTACK MODEL
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BASE OF POWER POLE
decay
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DECAY
maintenance
Average value
1.0
Relative strength
0.5
0
0
40
20
Time (yrs)
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TERMITES
maintenance
Average time to failure
1.0
Relative strength
0.5
0
0
40
20
Time (yrs)
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WIND RESISTANCE
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Darwin 1974
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TIMBER FRAME
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Brick and steel
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CYCLONE LOADING
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ENGINEERED CONSTRUCTION
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SERVICEABILITY LIMIT STATES
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STRUCTURAL SERVICEABILITY (Criteria)

• Deformation
• vibration
• sway
• cracking
• leakage

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SERVICEABILITY

• perception
• annoyance
• discomfort
• fear

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DIFFICULTIES
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Daily Quality Control
Underestimate strength Producer incurs cost
penalty Over-estimate strength Builder risks
failure
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Borer attack
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FABRICATION ERRORS
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Probability that a zero strength finger joint
occurs is 110000
Number of finger joints in tension is 2000
Hence probability of a non-glued joint occurring
within the total structure is 1 in 5
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NOT ACCEPTABLE OPTIONS
Fabrication so that probability of a non-glued
joint is less than 10-7
Design so that failure of single element is
acceptable
Reduce design strength by factor of 0.3
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CHOSEN OPTION
proof test every finger joint
!??!!!
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INTERNATIONAL TRADE
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TRADE
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90x35 Machine graded MGP 10 Australian Radiata
Pine
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FUTURE
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structure
people

• Comfort level
• Risk acceptance
• Behaviour (fire)
• Error

environment
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Conclusion 2
FUTURE RESEARCH FOCUS

• Prediction models for Performance based Criteria
• Rapid assessment procedures for Engineered Wood
  Products

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Conclusion 2
FUTURE RESEARCH FOCUS

• Separate the criteria for Cottage and Engineered
  construction
• Research on human factors

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Concluding Comment
Ecological footprint for each person in North
America is 4.5 hectares
On a global basis the available land per
person is 1.5 hectares
Use of timber for building comprises 20 of the
non-energy component
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