For WCTE 2014

1. EVALUATION OF RESTORING FORCE
CHARACTERISTICS OF MUD-WALLS
CONSIDERING EFFECT OF WALL-HEIGHT FOR
SEISMIC STRUCTURAL DESIGN
Hiroyuki Nakaji, Masami Gotou,
Hiro Kawahara, Yoshiyuki Suzuki

2. OBJECTIVE
• To propose the restoring force characteristics of mud-walls for seismic
structural design of wooden houses
• There is not enough information or manual on the structural design of
traditional timber buildings
• (Do we really need the rules?)
• To compare with the usual height of 2730 mm
• Two different heights of specimens with same length
• Wall-height influences on the restoring force characteristics?

3. CONCLUSIONS (in advance)
• The effect of wall-height is not significant on the restoring force
characteristics of mud-walls
• It can be assumed on the structural design of mud-walls that the wall-height’s
effect is negligible
• The restoring force characteristics for the seismic structural design
were proposed and confirmed in some mud-wall cases

4. SPECIMENS WITH DODAI
High
Low
Length
2P=1820mm
Height

5. SPECIMENS WITH ASHIGATAME

6. COLUMN CONNECTIONS
車知栓 雇いほぞ
h
車知栓
雇いほぞ
W
h/2
w
e s
Yatoi-Hozo
Shachi-Sen
Yatoi-HozoShachi-Sen
Nagahozo
Komisen

7. NAMING OF SPECIMENS
MWD-2Hn-1
Mud-Wall
With Dodai/Ashigatame
Wall-length is
1820 mm (2P)
Number of specimen
Wall-height is High/Low
How many Nuki
in High specimen

8. MUD-WALL SPECIMENS (2010-2012)
Name
Length
(mm)
Height
(mm)
Number Tested at when
MWD-2 1820 2730 10 TUES* 2010
MWA-2 1820 2730 3 KIT** 2010
MWD-2H4 1820 3600 3 TUES 2012
MWD-2H3 1820 3600 1 TUES 2012
MWD-2H5 1820 3600 1 TUES 2012
MWD-2L 1820 2100 3 TUES 2012
MWA-2H4 1820 3600 3 KIT 2012
MWA-2H3 1820 3600 1 KIT 2012
MWA-2H5 1820 3600 1 KIT 2012
MWA-2L 1820 2100 3 KIT 2012
* Tottori University of Environmental Studies
** Kanazawa Institute of Technology

9. Timber Frameworks
on Aug 22 2012
MWD-2H3
MWD-2H5

10. MWD-2L

11. Takekomai
on Aug 27 2012

12. Arakabe + Uragaeshi
on Aug 28-30 2012

15. Arakabe dried
1 month later
MWD-2L

16. Nakanuri
on Sep 25-27 2012

17. Nakanuri

19. MUD-WALL THICKNESS = 60 mm
Nakanuri 12 mm both side
Arakabe 36 mm = 18 x 2

20. SHEAR CYCLIC LOADING TESTS
MWD-2H4-3
on Dec 11 2012

21. LOADING PROCEDURE
- 1/10
- 3/40
- 1/20
- 1/40
0
1/40
1/20
3/40
1/10
• The deformation angle was
increased in stages 1/480, 1/240,
1/120, 1/90, 1/60, 1/45, 1/30,
1/20, 1/15, 1/10, and 1/7 rad
• 1/7 rad was only for Low
specimens
• Each deformation was cyclically
produced twice or three times
• Actuator’s stroke was controlled

22. MEASUREMENT
Deformation Angle (rad)

23. SETUP OF MWD-2H4
Two 9.62kN Steel Weights
+

24. DATA RECORDING (MWD CASE)
• 6-8 seconds interval
• Displacements and strains
• Take a photo at the same time
• MP4 movie file was created from thousands of photos with Movie Maker
after the experiment

25. SILENT VIDEO (~3 MINUTES)

26. P-DELTA EFFECT
𝑃′ = 𝑃 + 𝑊 tan 𝛾
𝑃′ : Restoring force (kN)
P: Measured load (kN)
W: Steel weight 9.62 × 2 (kN)
g: Deformation angle (rad)
-15
-10
-5
0
5
10
15
-0.15 -0.1 -0.05 0 0.05 0.1 0.15
-15
-10
-5
0
5
10
15
-0.15 -0.1 -0.05 0 0.05 0.1 0.15
P
P’
g
MWD-02H4-3

27. -15
-10
-5
0
5
10
15
-0.15 -0.1 -0.05 0 0.05 0.1 0.15
restoringforce(kN) deformation angle (rad)
-15
-10
-5
0
5
10
15
-0.15 -0.1 -0.05 0 0.05 0.1 0.15
restoringforce(kN)
deformation angle (rad)
-15
-10
-5
0
5
10
15
-0.15 -0.1 -0.05 0 0.05 0.1 0.15
restoringforce(kN)
deformation angle (rad)
-15
-10
-5
0
5
10
15
-0.15 -0.1 -0.05 0 0.05 0.1 0.15
restoringforce(kN)
deformation angle (rad)
LOAD-DEFORMATION CURVE (MWD)
MWD-2H4-1 MWD-2H4-2
MWD-2H3-1 MWD-2H5-2

28. -15
-10
-5
0
5
10
15
-0.15 -0.1 -0.05 0 0.05 0.1 0.15
restoringforce(kN)
deformation angle (rad)
-15
-10
-5
0
5
10
15
-0.2 -0.1 0 0.1 0.2
restoringforce(kN)
deformation angle (rad)
-15
-10
-5
0
5
10
15
-0.2 -0.1 0 0.1 0.2
restoringforce(kN)
deformation angle (rad)
-15
-10
-5
0
5
10
15
-0.2 -0.1 0 0.1 0.2
restoringforce(kN)
deformation angle (rad)
LOAD-DEFORMATION CURVE (MWD)
MWD-2L-1 MWD-2L-2
MWD-2L-3 MWD-2H4-3

29. MWD-2H4-3, 1/90 RAD
small cracks

30. MWD-2H4-3, 1/20 RAD
many cracks

31. -15
-10
-5
0
5
10
15
-0.15 -0.1 -0.05 0 0.05 0.1 0.15
Deformation Angle [rad]
RestoringForce[kN]
2H3
-15
-10
-5
0
5
10
15
-0.15 -0.1 -0.05 0 0.05 0.1 0.15
Deformation Angle [rad]
RestoringForce[kN]
2H4-1
2H4-2
2H4-3
-15
-10
-5
0
5
10
15
-0.15 -0.1 -0.05 0 0.05 0.1 0.15
Deformation Angle [rad]
RestoringForce[kN]
2H5
-15
-10
-5
0
5
10
15
-0.15 -0.1 -0.05 0 0.05 0.1 0.15
Deformation Angle [rad]
RestoringForce[kN]
2L3-1
2L3-2
2L3-3
LOAD-DEFORMATION CURVE (MWA)
1/45 rad
1/30 rad

32. DAMAGE AT 1/10 RAD (MWD)
MWD-2H4-1 MWD-2L-1

33. DAMAGE AT 1/10 RAD (MWA)
MWA-2H4-1 MWA-2L-1

34. ENVELOPE CURVES
0
2
4
6
8
10
12
14
16
0 1/20 1/10
restoringforce(kN)
deformation angle (rad)
MWD-2H4-1
MWD-2H4-2
MWD-2H4-3
MWD-2H3-1
MWD-2H5-1
MWD-2L-1
MWD-2L-2
MWD-2L-3
MWD-2 Ave.
MWD-2 95% Lower
MWD-2 95% Upper
0
2
4
6
8
10
12
14
16
0 1/20 1/10
restoringforce(kN)
deformation angle (rad)
MWA-2H4-1
MWA-2H4-2
MWA-2H4-3
MWA-2H3
MWA-2H5
MWA-2L-1
MWA-2L-2
MWA-2 Ave.
MWA-2 95% Lower
MWA-2 95% Upper
MWD-2 MWA-2

35. PROPOSAL OF RESTORING FORCE
CHARACTERISTICS OF MUD-WALLS
0
20
40
60
80
100
120
0 1/20 1/10
shearstress(kN/m2)
deformation angle (rad)
1P-1.5P
1.5P-2P
MM
H
Q=2M/H Q=M/H
M
Mud-Wall Timber Framework Mud-Wall Plate
Column joint can
resist bending
moment
Two lines are suggested
because failure mode is
different

36. ASSUMPTIONS
• Superposition principle is applicable, that is, Mud-wall is really a mud-
wall plate itself plus timber framework
• Wall-Length has an effect on the restoring force characteristics
• Timber framework resists the horizontal loading at joints of members.
For example, if a column joint is made using Nagahozo (mortise-
tenon) and strengthened by Komisen (cotter-pin), the joint can resist
bending moment

37. NAGAHOZO + KOMISEN JOINT
0
0.25
0.5
0.75
1
1.25
1.5
0 0.025 0.05 0.075 0.1
restoringmoment(kN.m)
deformation angle (rad)

38. COMPARE WITH TEST RESULTS
MWD-2 (Average) MWA-2 (Average)
0
2
4
6
8
10
12
14
0 0.025 0.05 0.075 0.1
restoringforce(kN)
deformation angle (rad)
MWD-2*
Proposal
0
5
10
15
0 0.025 0.05 0.075 0.1
restoringforce(kN)
deformation angle (rad)
MWA-2
Proposed

39. CONCLUSIONS
• The effect of wall-height is not significant on the restoring force
characteristics of mud-walls
• It can be assumed on the structural design of mud-walls that the wall-height’s
effect is negligible
• The restoring force characteristics for the seismic structural design
were proposed and confirmed in some mud-wall cases