Transcript Timber, a truly sustainable resource, can be used to replace steel

Timber, a truly sustainable resource, can be
used to replace steel and concrete structures
in multi-storey building.
John Chapman, Senior Lecturer
School of Architecture, University of Auckland
Introduction to recent timber building research School of Architecture, University of Auckland
• pinus radiata timber
poles as the main
structural elements in
commercial / industrial
building
• research is in response to
the advantages of timber
as a sustainable material
• 4 separate, but
interrelated, studies
Environmental Reasons for radiata
poles as structural elements in building
• radiata poles are
-
a renewable resource
-
require little energy during
manufacture
-
absorb carbon from the
atmosphere and reduce
greenhouse gases
Other Reasons for
radiata poles as building
structural elements
• Competent
structural product
• higher failure stresses
than sawn lumber
• cheap timber at
NZ$350/cu.m
–
Images by Andrew Charleson – senior lecturer
Victoria University
Study 1: Radiata Poles as the Columns
in Multi-storey Timber Building
Study 2 – Investigating Timber Floor
Types for Commercial Building
• floor structure types:
– glulam
– timber trusses
– LVL (linear veneer lumber)
• office live loading of 3 Kpa
• resulting timber floors
compared for cost and
volumes of timber.
Study 3: Large
Industrial Truss
Structures Using Pinus
Radiata Poles
Study 4: Six Storey Apartment Building
using Radiata Poles for the Beam and
Column Structural Elements
• results of studies 1 to3 led to the
proposal that timber poles were very
suited for the structural elements in
medium storey apartment building
Apartment Plans
• beams and posts can
be arranged as simple
posts and beams
Prototype Pole Building-Plan of Units (figure 1)
• resistance to horizontal
loads supplied by the
frequent party walls
• floor is timber
– floor beams are pairs of
radiata poles
Prototype Pole Building-Plan of Main Structure ( figure 5)
Apartments Cross Section
• The research considered
seven aspects of the
prototype pole building
– dimensional stability of the
timber
– environmental impact
– building strength
– non destructive testing of
poles
– economics
– fire resistance
– sound insulation
Environmental Impact
• Pole building structure
– Energy for manufacture
= 0.5 Gj/sq.m.
– Total carbon absorbed from
atmosphere
= 27.4 Kg/sq.m.
• Equivalent RC structure
– Energy for manufacture
= 2.24 Gj/sq.m.
– Total carbon emitted into
atmosphere
= 52.5 Kg/sq.m.
Building Strength
• pole members
readily available
• for major
earthquake zones,
column pole
diameters increase
by 50mm approx
Non Destructive Testing of
Timber Poles
• Acousto-ultrasonic
based methods relate
propagation velocity of
the longitudinal wave
with wood density and
modulus of elasticity
• Acousto-ultrasonic
testing detects pole
defects.
Economics
• pole/timber structure is 89% the cost of the
equivalent reinforced concrete structure
– Pole building structure =
– Equivalent R.C.
=
US$124.40 / sq.m.
US$208.70 / sq.m.
• timber buildings are significantly lighter than
the R.C. alternatives and have reductions in
foundation costs. (not considered in above cost
analysis)
Fire Resistance
• each residential unit is an independent fire cell
– pole structure & party walls are plasterboard lined
• 80mm expected loss of pole diameter in 1 hour
fire
– Poles will continue to support building after 1 hour fire
Sound Insulation
•
50mm thick concrete floor toppings to protect from vertical noise transference
•
Horizontal insulation at party walls assisted by fibreglass blanket between two
separated timber frames
•
Sound transference the main obstacle to timber building. Research occurring at the
University of Auckland Acoustics Research Centre and elsewhere in world
Conclusions to Radiata Poles as the
Columns in Multi-storey Timber Building
• no impediments to radiata poles as
main structural members in multistorey of up to at least 6 storeys
• 6 storey apartment building most
complete project
– considered more deeply the
issues and perceived problems
• Further research into this low
energy, sustainable, and
atmosphere assisting building
product is continuing