Structural Behaviour of Bamboo-Steel Reinforced CSRE Column
6.4 Summary and conclusions
Chapter 6 Structural Behaviour of Bamboo-Steel Reinforced CSRE Column
108 becomes more effective and carries more load than bamboo at ρw equal to 2.51. The reason for this difference can be due to steel being stronger material than bamboo.
The comparison of δuv and δl60 between SR and BSR CSRE columns are shown in Figs. 6.12a and b respectively. It can be seen that the values of δuv and δl60 for SR are found to be higher than those of BSR by ~8% and ~16 % respectively, for greater tie spacing i.e. 100 mm and 200 mm. However, a relatively sharp improvement in δuv and δl60 can be seen for SR when the tie spacing is reduced towards 50 mm from 100 mm, in comparison to BSR wherein a gradual trend is maintained for all the tie spacing considered (i.e. 200 mm to 50 mm). The enhanced deformation improvement trend in SR as compared to BSR, may be related to the improved confinement core strength achieved as a result of the higher strength in longitudinal steel (i.e. confinement effect has relatively increasing effect in mobilising the strength/stiffness of higher strength steel as compared to bamboo).
Chapter 6 Structural Behaviour of Bamboo-Steel Reinforced CSRE Column
109 4. Linear increase in percent Pubs is observed as ρt was increased from 0% to 3.41%. There is a gradual increase on percent Pubs as ρt was increased from 0% to 1.52%, 2.15% and 3.41% with the values of 4%, 10% and 16%
respectively. The Pubs also increases by about 6% to 12% when ρw was increased from 0.63% to 1.26% and 2.51% respectively, thus showing an improvement in ductility.
5. Bamboo possess reasonably high tensile property i.e., half the strength of steel, hence it can be used as a potential reinforcing material and a substitute to steel to some extent for construction of rammed earth structures in order to achieve higher strength and better seismic performance.
TH-1414_11610428
Chapter 6 Structural Behaviour of Bamboo-Steel Reinforced CSRE Column
110 Table 6.1. Details of bamboo-steel reinforcement.
Column a (mm) d (mm) h (mm) s (mm) ρl (%) ρw (%) ρl + ρw (%)
1BSR200 150 150 1500 200 0.89 0.63 1.52
2BSR200 150 150 1500 200 0.89 0.63 1.52
3BSR200 150 150 1500 200 0.89 0.63 1.52
1BSR100 150 150 1500 100 0.89 1.26 2.15
2BSR100 150 150 1500 100 0.89 1.26 2.15
3BSR100 150 150 1500 100 0.89 1.26 2.15
1BSR50 150 150 1500 50 0.89 2.51 3.41
2BSR50 150 150 1500 50 0.89 2.51 3.41
3BSR50 150 150 1500 50 0.89 2.51 3.41
TH-1414_11610428
Chapter 6 Structural Behaviour of Bamboo-Steel Reinforced CSRE Column
111 Table 6.2. Summary of bamboo-steel reinforced column test results.
Column
Ultimate load (kN)
Comp.
strength (MPa)
Moisture content of specimen (%)
Average moisture content at test (%)
Standard deviation (%)
Average dry density of
CSRE (kg/m3)
Standard deviation
(%) Locations
Top Middle Bottom
CSRE Bamboo CSRE Bamboo CSRE Bamboo CSRE Bamboo CSRE Bamboo
1UCSRE 81.0 3.60 5.43 - 6.79 - 5.45 - 5.89 - 0.78 - 1790 0.012
2UCSRE 80.3 3.57 6.29 - 5.79 - 4.85 - 5.64 - 0.73 - 1800 0.015
3UCSRE 81.6 3.49 5.67 - 6.56 - 5.78 - 6.00 - 0.49 - 1790 0.013
1BSR200 83.7 3.72 5.52 2.82 6.97 3.85 7.91 3.87 6.80 3.34 1.20 0.73 1950 0.029
2BSR200 82.2 3.65 5.97 2.80 6.28 4.02 7.04 7.92 6.43 3.41 0.56 0.86 1930 0.010
3BSR200 83.3 3.70 5.62 3.33 6.77 3.85 7.81 3.97 6.70 3.72 1.10 0.34 1950 0.011
1BSR100 89.1 3.96 7.97 3.09 5.27 3.80 8.12 3.80 7.12 3.56 1.60 0.50 1940 0.022
2BSR100 87.3 3.88 7.39 4.60 7.15 3.99 6.32 3.11 6.95 3.90 0.56 0.43 1940 0.010
3BSR100 86.8 3.86 7.12 3.73 6.12 3.63 7.15 3.47 6.64 3.72 0.77 0.47 1950 0.020
1BSR50 95.0 4.22 8.49 5.57 7.52 6.67 7.19 4.82 7.73 5.69 0.68 0.78 1930 0.014
2BSR50 91.3 4.06 6.73 6.19 6.81 3.50 5.35 5.41 6.30 5.03 0.82 1.90 1960 0.014
3BSR50 93.7 4.16 7.23 5.61 5.84 4.73 6.21 5.13 6.78 5.42 0.63 0.97 1950 0.009
Note: UCSRE = Unreinforced Cement stabilised Rammed Earth; BSR = Bamboo-Steel Reinforced; 1, 2, 3 = Serial number of columns; 50, 100, 200 = Spacing of lateral ties in mm.
TH-1414_11610428
Chapter 6 Structural
(b) Typical load
P(kN)
Test setup
Structural Behaviour of Bamboo-Steel Reinforced CSRE Column
(a) Bamboo splint.
(b) Typical load-deformation curve of bamboo splint
Fig. 6.1 Testing of bamboo splint.
0 1 2 3 4 5 6 7 8
0 5 10 15 20 25
δt (mm) Test setup
Failed sample (un
Failed sample (noded)
Steel Reinforced CSRE Column
112 deformation curve of bamboo splint.
25
Failed sample (un-noded)
Failed sample (noded)
TH-1414_11610428
Chapter 6 Structural Behaviour of Bamboo-Steel Reinforced CSRE Column
113
Fig. 6.2. Reinforcement details of column with tie spacing: (a) 50 mm; (b) 100 mm;
and (c) 200 mm.
100 mm c/c spacing
150
(All dimensions in mm) (b) 4 Nos. 8 mm ϕ bamboo strip
6 mm ϕ steel ties
50 mm c/c spacing
(a)
150
30 mm cover
200 mm c/c spacing 1500
(c) 60 mm leg
TH-1414_11610428
Chapter 6 Structural
(a)
Fig. 6.3. Equipments:
typical bamboo-steel reinforced CSRE column
Bamboo splint
Mould
Structural Behaviour of Bamboo-Steel Reinforced CSRE Column
(b)
(a) mould; (b) rammer and compaction plate with hole steel reinforced CSRE column.
Bamboo lints
Compaction plate with holes 5 kg rammer
Steel Reinforced CSRE Column
114 (c)
ammer and compaction plate with holes; and (c)
TH-1414_11610428
Chapter 6 Structural
(a)
Fig. 6.4. Failure of column with lateral deformation curve
Structural Behaviour of Bamboo-Steel Reinforced CSRE Column
(b) column with 200 mm tie spacing: (a) failure pattern curve.
0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500
0 0.5
h(mm)
Buckling of bamboo splint
Ties
Shear wedge
Spalling of cover
65°-75°
Steel Reinforced CSRE Column
115 (b)
lure pattern; and (b) load- 0.5 1 1.5 2 2.5
δl(mm) BSR200
10 kN 20 kN 30 kN 40 kN 50 kN 60 kN Pubs= 83.1 kN
TH-1414_11610428
Chapter 6 Structural
(a)
Fig. 6.5. Failure of column with lateral deformation curve
~ 200 mm Steel
bracket Spalling of cover due to compression crushing
Structural Behaviour of Bamboo-Steel Reinforced CSRE Column
(b) column with 100 mm tie spacing: (a) failure pattern curve.
0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500
0 0.5 1
h (mm)
δl(mm) BSR100
Spalling of cover due to compression crushing
Tension crack opening
Ties
Breaking of splint
Steel Reinforced CSRE Column
116 (b)
ailure pattern; and (b) load- 1 1.5 2 2.5
(mm) BSR100
10 kN 20 kN 30 kN 40 kN 50 kN 60 kN Pubs= 87.7 kN
TH-1414_11610428
Chapter 6 Structural
(a)
Fig. 6.6. Failure of column with vs. lateral deformation
~ 250 mm
Tension crack tip Steel bracket
Spalling of cover due to compression crushing
Structural Behaviour of Bamboo-Steel Reinforced CSRE Column
(b) column with 50 mm tie spacing: (a) failure pattern deformation curve.
0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500
0 0.5 1 1.5
h(mm)
δl (mm) BSR50 Pubs
Spalling of cover due to compression crushing
Breaking of splint
Ties
Steel Reinforced CSRE Column
117 (b)
lure pattern; and (b) load 1.5 2 2.5 3
(mm) BSR50
10 kN 20 kN 30 kN 40 kN 50 kN 60 kN
ubs= 93.3 kN
TH-1414_11610428
Chapter 6 Structural Behaviour of Bamboo-Steel Reinforced CSRE Column
118
(a) UCSRE column (b) BSR200 column
(c) BSR100 column (d) BSR50 column
Fig. 6.7. Load vs. axial deformation curves.
0 20 40 60 80 100
0 0.5 1 1.5 2 2.5 3 3.5
Axial load, P(kN)
δv (mm)
1UCSRE 2UCSRE 3UCSRE
0 20 40 60 80 100
0 3 6 9 12 15 18 21
Axial load, P(kN)
δv (mm)
1BSR200 2BSR200 3BSR200
0 20 40 60 80 100
0 3 6 9 12 15 18 21
Axial load, P (kN)
δv (mm)
1BSR100 2BSR100 3BSR100
0 20 40 60 80 100
0 3 6 9 12 15 18 21 24 27
Axial load, P (kN)
δv (mm)
1BSR50 2BSR50 3BSR50
TH-1414_11610428
Chapter 6 Structural Behaviour of Bamboo-Steel Reinforced CSRE Column
119
(a) (b)
Fig. 6.8. Effect of tie spacing: (a) axial deformation of columns at ultimate load (δuv);
and (b) lateral deformation of columns at 60 kN load (δl 60).
(a) (b)
Fig. 6.9. Effect of reinforcement on load ratio (Pubs/Pu ) of column: (a) load ratio vs.
total reinforcement; and (b) load ratio vs. lateral reinforcement.
0 2 4 6 8 10 12 14
50 100 150
200 250
δuv(mm)
Tie spacing (mm) BSR
0 0.5 1 1.5 2 2.5 3
50 100 150 200 250 δl 60(mm)
Tie spacing (mm) BSR
y = -0.019x2+ 0.165x + 0.832 R² = 1
0.90 0.95 1.00 1.05 1.10 1.15 1.20 1.25
0 0.5 1 1.5 2 2.5 3 3.5 4
Pubs/Pu
ρl+ρw
y = -0.019x2+ 0.130x + 0.964 R² = 1
0.90 0.95 1.00 1.05 1.10 1.15 1.20 1.25
0 0.5 1 1.5 2 2.5 3
Pubs/Pu
ρw ρl = 0.89%
ρl = 0.89%
TH-1414_11610428
Chapter 6 Structural Behaviour of Bamboo-Steel Reinforced CSRE Column
120
(a) (b)
Fig. 6.10. (a) Load-capacity of BSR and SR columns with respect to total reinforcement ratio; and (b) load-capacity of BSR and SR columns with respect to lateral reinforcement.
Fig. 6.11. Effect of longitudinal reinforcement type on load-capacity.
60 70 80 90 100 110 120
1 1.5 2 2.5 3 3.5 Pubs, Pus(kN)
ρl+ ρw
BSR SR
UCSRE
1.52 2.15 3.14
60 70 80 90 100 110 120
0.5 1.13 1.76 2.39 3.02 Pubs, Pus(kN)
ρw
BSR SR
UCSRE
50 60 70 80 90 100 110 120
0.7 1.7
Pubs, Pus (kN)
Reinforcement type
BSR50; SR50 BSR100; SR100 BSR200; SR200
BSR SR
TH-1414_11610428
Chapter 6 Structural Behaviour of Bamboo-Steel Reinforced CSRE Column
121
(a) (b)
Fig. 6.12. Comparison of SR and BSR columns on (a) axial deformation at ultimate load (δuv); and (b) lateral deformation at 60 kN load (δl 60).
0 2 4 6 8 10 12 14 16
50 100 150
200 250
δuv(mm)
Tie spacing (mm)
SR BSR
0 1 2 3 4 5 6
50 100 150
200 250
δl 60(mm)
Tie spacing (mm)
SR BSR
TH-1414_11610428
Chapter 7 Conclusions and Future Scope of Work
122