in-plane testing of timber-concrete composite floors · in-plane testing of timber-concrete...
TRANSCRIPT
In-Plane Testing of
Timber-Concrete Composite Floors
Students: Michael Newcombe & Wouter van Beerschoten
Supervisors: Dr. David Carradine, Assc. Prof. Stefano Pampanin
& Prof. Andy Buchanan
→ Post-tensioned frames and walls
→ Long spans
→ Thin concrete topping (TCC flooring)
→ Timber diaphragm connections
Potential for high floor flexibility…
New forms of multistorey timber buildings are evolving:
INTRODUCTION
(c.o. N. Perez)
BACKGROUND
Is floor flexibility a problem?
→ 1994 Northridge
- Several structures collapsed
- Higher diaphragm forces
- Higher drift demands on gravity systems
→ Lots of research on long span precast
concrete floors with concrete LLRS
(Fleischman, Lee and Kuchma, Miranda…)
→ Little investigation with solid timber LLRS
OBJECTIVES
Experimental:
Analysis:
1. Establish performance of
different diaphragm connections
2. Deformation components
3. Identify structural types that
may have a problem
4. Provide recommendations for
modeling
Dcon Dshear Dflexure
EXPERIMENTAL
Diaphragm Connections:
- Concrete-to-timber
Dowels (at 90°)
Screws
Inclined (at 45 °)
- Timber-to-timber:
Dowels (at 90°)
Screws
Inclined (at 45 °)
Nails Dowels (at 90°)
EXPERIMENTAL
Performance of Connections:
Conc.-Timber
Screws
90°
-15 -10 -5 0 5 10 15
Displacement (mm)
-40
-30
-20
-10
0
10
20
30
40
Force
(k
N)
EXPERIMENTAL
Conc.-Timber
Screws
45°
Performance of Connections:
-10 -5 0 5 10
Displacement (mm)
-80
-70
-60
-50
-40
-30
-20
-10
0
10
20
30
40
50
60
70
80
Force
(k
N)
EXPERIMENTAL
Performance of Connections:
Timber-Timber
Screws
90°
-15 -10 -5 0 5 10 15
Displacement (mm)
-50
-40
-30
-20
-10
0
10
20
30
40
50
Force
(k
N)
EXPERIMENTAL
Performance of Connections:
Timber-Timber
Nails
90°
-20 -15 -10 -5 0 5 10 15 20
Displacement (mm)
-80
-70
-60
-50
-40
-30
-20
-10
0
10
20
30
40
50
60
70
80
Force
(k
N)
EXPERIMENTAL
Performance of Connections:
Timber-Timber
Screws
45°
-20 -15 -10 -5 0 5 10 15 20
Displacement (mm)
-60
-50
-40
-30
-20
-10
0
10
20
30
40
50
60
Force
(k
N)
EXPERIMENTAL
Summary floor testing:
- Connection backbone curves vary
- Inclined fasteners are 4 times
stiffer than dowels
- Timber and concrete connections
with screws have the same stiffness
- Dcon >> Ddiaphragm
- Timber-to-timber connections:
→Easy construction and repair
→Less damage -15 -10 -5 0 5 10 15
Displacement (mm)
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
Fo
rce p
er f
ast
ener
(kN
)
Test 1
Test 2
Test 3
Test 4
Test 5
ANALYSIS
Q: For which structures do we need to model floor flexibility?
And to what complexity?
FRAMES
WALLS
Perform numerical analysis
(considering Kdiaphragm from testing)
Consider different floor geometries
Consider different LLRS
(single storey)
Consider different floor models
MDOF
SDOF 1
SDOF 2
0.90
0.95
1.00
1.05
1.10
1.15
1.20
1.25
1.30
1.35
1.40
0.00 0.04 0.08 0.12 0.16 0.20 0.24
Period, Tconn [s]
Dm
do
f / D
sd
of
0.90
0.95
1.00
1.05
1.10
0.00 0.04 0.08 0.12 0.16 0.20 0.24
Period, Tconn [s]
Dm
do
f / D
sd
of
ANALYSIS
Single storey results: Amplification of most flexible floor
FRAMES
Rigid Design limits
WALLS
0.70
1.20
1.70
2.20
2.70
3.20
0.00 0.04 0.08 0.12 0.16 0.20 0.24
Period, Tconn [s]
PF
A / P
GA
0.70
1.20
1.70
2.20
2.70
3.20
0.00 0.04 0.08 0.12 0.16 0.20 0.24
Period, Tconn [s]
PF
A / P
GA
ANALYSIS
Single storey results: Amplification of most flexible floor
FRAMES
Rigid Design limits
WALLS
ANALYSIS
Summary for single storey:
-For frame design:
Assume the diaphragms are rigid (within 2.5%)
- For wall design:
Model the diaphragm connections as a SDOF (within 5%)
ANALYSIS
Multistorey frames:
- Check the rigid diaphragm assumption
- Compare Rigid and SDOF floor
models
- What are the effects of higher
modes in the structure and
non-linear floor response
1/2500y:1/500y:1/50y:
ANALYSIS
Results for multistorey frames:
0.0
3.8
7.6
11.4
15.2
19.0
22.8
0.0% 1.0% 2.0% 3.0% 4.0% 5.0%
Drift
Heig
ht
[m]
0.0
3.8
7.6
11.4
15.2
19.0
22.8
0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75
PFAi / PGA
He
igh
t [m
]
Design
TargetFlexible
Rigid
Flexible
Rigid
Flexible
Rigid
ANALYSIS
Results for multistorey frames:
- Floor response spectra (since the floor diaphragm is a SDOF)
0
1
2
3
4
5
0 1 2 3 4 5
Period [s]
Ac
cle
rati
on
s [
g]
0
1
2
3
4
5
0 1 2 3 4 5
Period [s]
Ac
cle
rati
on
s [
g]
0
1
2
3
4
5
0 1 2 3 4 5
Period [s]
Ac
cle
rati
on
s [
g]
0
1
2
3
4
5
0 1 2 3 4 5
Period [s]
Ac
cle
rati
on
s [
g]
0
1
2
3
4
5
0 1 2 3 4 5
Period [s]
Ac
cle
rati
on
s [
g]
0
1
2
3
4
5
0 1 2 3 4 5
Period [s]
Ac
cle
rati
on
s [
g]
0
1
2
3
4
5
0 1 2 3 4 5
Period [s]
Ac
cle
rati
on
s [
g]
0
1
2
3
4
5
0 1 2 3 4 5
Period [s]
Ac
cle
rati
on
s [
g]
T1T2
T3
Tconn
ANALYSIS
Summary for multistorey frames:
- Rigid floor diaphragm assumptions is O.K.
- Inelasticity in the floor connections reduces the peak floor
accelerations
- The ground (design) spectrum can be used to determine the
peak floor accelerations
Tconn
PFA
T [s]Tconn