This document summarizes research on Glubam-concrete composite beams (BCC). Key points include: 1) Various connector types between the Glubam beam and concrete slab were tested, including steel mesh, screws, and notches. Four connector types were found suitable for BCC beams. 2) Short-term bending tests on BCC beams showed acceptable mechanical properties and efficiency compared to theoretical fully composite and non-composite beams. Failure modes depended on connector type. 3) Long-term tests on connectors and beams showed deflections fluctuated with environment but would not exceed service limits in 50 years. Predicted deflections matched experimental data. 4) A new UHPC-steel tube

1. GluBam-concrete
Composite Beams
SHAN Bo Ph.D
China Ministry of Education Key Laboratory of Building
Safety and Energy Efficiency,
Hunan University, China

2. Contents
• Research background
• Push-out tests of BCC system
• Short-term bending tests
• Long-term tests of BCC beams
• Research progress

3. Introduction-GluBam®
Compressive
strength (MPa)
Tensile
strength(MPa)
Bending
strength
(MPa)
Density
(kg/m3)
Elastic modulus
(MPa)
54 80 75 880 9400
Basic dimension:
2440mm long by 1220mm
wide (or 8ft. by 4ft.)
Thickness from 20mm to
30mm.
ØGluBam（glued laminated bamboo） as a new kind of structural material has
been developed by Xiao (2007).

4. Meixihu bamboo
house(2012)
Ø Some demonstration buildings have
been constructed by using glubam
as mainly structural material.

5. Leiyang traffic bamboo bridge(2007)
ØGlubam-only flexural member shows
relatively low stiffness and it will lead
to increase deflection.
0 20 40 60 80 100 120 140 160
0
20
40
60
80
100
120
Load(mm)
Deflection (mm)
GB-1
GB-2
GB-3
CFRP
Service limit state

6. Glubam-Concrete Composite(BCC)
Concrete slab
Shear
connector
Glubam beam
Ø In BCC system, the excellent performance of two materials can be utilized, in which
glubam carries tensile force and concrete resists compression.
Ø Compare to the RC beam, BCC have better efficiency in terms of strength to self-
weight ratio, better seismic and environmental friendly performance.
Ø Compared to a glubam-only beam, BCC have higher stiffness, better vibrating
isolation and fire resistance.
Load

7. Contents
• Research background
• Push-out tests of BCC system
• Short-term bending tests
• Long-term tests of BCC beams
• Research progress

8. Type Description of the connection system Schematic diagram
SM Continuous steel mesh embedded into
the concrete slab.
SC A threaded screw glued into the
GluBam beam.
SC-N
SP A folded steel plate embedded into the
concrete.
NC-0 A notch in bamboo beam.
NC-0N
PNC A pre-tightening screw and a notch in
bamboo beam
α
Protective
plastic pipe

9. Test setup
Loading protocol: European standard EN 26891-1991.

10. SM （steel mesh）
0.0 0.5 1.0 1.5 2.0 2.5
0
30
60
90
120 k0.6
k0.8
k0.4
Shearforce(kN)
Slip (mm)
GluBam delaminated
crack
Buckled steel mesh
Shear force-slip curves

11. SC (screw)
Bending of screw
Delaminated cracking of
GluBam
Shear force-slip curves
0 1 2 3 4
0
10
20
30
40
50
k0.8
k0.6
Shearforce(kN)
Slip (mm)
k0.4

12. NC and PNC (notch in glubam beam)
Inclined crack in notched
concrete
Bending of screw
Shear force-slip curves
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
0
20
40
60
80
100
120
140
k0.4
k0.6
k0.8
Shearforce(kN)
Slip (mm)

13. 0 2 4 6 8 10 12 14
0
20
40
60
80
100
120
140
160
180
200
SC-N
SC SC-W
SP
PNC
SM
Test curves
Fitting curves
NC-15
NC-0
NC-0N
Force(kN)
Slip (mm)
Shear force-slip relationship

14. Conclusions
• It was found that all composite connectors can be divided into two
groups: one group exhibited high stiffness but low ductility such as the
NC series, SM and PNC types; the other group exhibited high ductility
but low stiffness, as demonstrated by the SC series types.
• Four types of connector are suitable for BCC beams, including NC-0N,
SM, SC-N and PNC.

15. Contents
• Research background
• Push-out tests of BCC system
• Short-term bending tests
• Long-term tests of BCC beams
• Research progress

16. Experimental setup
Every beam with 8m long was simply supported and subjected to four-point bending test
to failure. The bending tests were performed under displacement control.

17. Fabrication of BCC specimens

18. Results and discussion
Finger joint fractured
at mid-span
Steel mesh yield and
tearing
Failure patterns of SM-2
0 20 40 60 80 100 120
0
40
80
120
160
200
No composite
Fully composite
Experimental
Numerical
SM-1
SM-2
Load(kN)
Mid-span deflection (mm)
0 10 20 30 40 50 60 70 80 90 100
0
10
20
30
40
50
60
70
80
90
100
Mid-span deflection (mm)
Efficiency(%)
SLS
ULSSLS
SM-1
SM-2
ULS

19. Sheared out of
GluBam at end
Lag screw yielded at
the end
Failure patterns of SC-25
0 20 40 60 80 100 120 140
0
40
80
120
160
200
Mid-span deflection (mm)
Load(kN)
Experimental
Numerical
No composite
Fully composite
SC-25
SC-45
0 20 40 60 80 100 120 140
0
10
20
30
40
50
60
70
80
90
100
Mid-span deflection (mm)
Efficiency(%)
ULS
SLS
SC-25
SC-45
ULS
SLS

20. Plasticization of screw
in the end connections
Crushing of concrete in
notched connection
Failure patterns of NC
0 20 40 60 80 100 120
0
30
60
90
120
150
180
Load(kN)
Mid-span deflection (mm)
Experimental
Numerical
No composite
Fully composite
NC-12-R200
NC-8-R200
0 20 40 60 80 100 120
0
10
20
30
40
50
60
70
80
90
100
Efficiency(%)
Mid-span deflection (mm)
ULS
SLS
NC-8-R200
NC-12-R200
ULS
SLS

21. FEM analysis
0 3 6 9 12 15
0
40
80
120
160
200
PNC
NC-R100
SM
NC-R200
SC
Load(kN)
Slip (mm)
Constitutive relations of connector systems
FEM model

22. Experimental results of the tests to collapse performed on BCC beams
Specimen Fmax (kN) Max deflection (mm) End slip
(mm)
Strain at midspan (με) Efficiencies (%)
Concrete glubam
Exp Num Exp Num Top Bottom Top Bottom SLS ULS
SM-1 132.1 142.1 76.8 70.2 2.048 -877 343 -778 2262 77.4 59.7
SM-2 179.2 192.7 91.4 85.3 1.475 -929 481 -822 2393 83.2 70.6
SC-25 128.6 162.3 114.6 107.7 4.113 -865 548 -634 2154 60.1 42.9
SC-45 166.4 184.9 109.9 95.6 2.776 -798 153 -525 1733 75.0 49.3
NC-12-R100 107.6 121.4 95.7 88.7 5.842 -646 348 -534 1954 61.1 44.8
NC-16-R100 123.3 140.8 84.7 74.5 3.902 -713 136 -520 1421 67.5 46.5
NC-8-R200 121.3 135.2 85.9 78.1 4.013 -1157 352 -337 2408 69.9 49.1
NC-12-R200 148.1 162.3 81.3 73.9 3.345 -1130 152 -414 2787 73.1 54.3
PNC-16-R100 118.2 131.3 92.1 81.6 4.218 -440 77 -147 1687 70.9 46.2

23. Conclusions
• BCC beams present acceptable mechanical properties and can be used
in the actual projects.
• The analytical results from FEM model are close to the experimental
data.
• Further research are being performed in order to provide the design
method of BCC beams.

24. Contents
• Research background
• Push-out tests of BCC system
• Short-term bending tests
• Long-term tests of BCC beams
• Research progress

25. Long-term tests on connections
钢 板 网
2× 100× 400
混 凝 土 板
100× 400× 400
胶 合 竹 梁
112× 300× 400

26. Experimental results
SM SC
NC
PNC

27. Long-term tests on beams

28. Experimental results
=
1+
t
t,eff
t def
Ε
Ε
ψ k
=
1+
c
c,eff
c c
Ε
Ε
ψ Φ
1
s
eff
conn
K
K
Φ



29. Predicting results
Key events
Mid-span deflection（mm）
SM SC NC PNC
Load application 3.296 2.377 6.114 3.145
6 months
Experimental 6.761 5.2 9.519 5.248
Modified 6.725 5.136 9.398 5.154
Prediction of 1 year 7.151 5.5 9.506 5.375
Prediction of 50 years 16.533 10.183 20.796 10.268
SLS:25mm

30. Conclusions
• In the long-term tests, the mid-span deflection of BCC beams
fluctuated with the environment changed, which also decreased as the
temperature and relative humidity decreased.
• The analysis indicates that the ultimate deflection of the BCC beams
will not exceed the requirement in 50 years according to the service
limit state.

31. Contents
• Research background
• Push-out tests of BCC system
• Short-term bending tests
• Long-term tests of BCC beams
• Research progress

32. Shortcomings of classical connectors
螺杆混凝土板
胶粘剂
混凝土板
凹槽
抵承面倾角
胶合竹梁
胶合竹梁
Typical load-slip curves(TCC)（Richar M,2004）
Dowels Notches
Ø Both the dowels and the notches have
insufficient performance.
Ø The two types are not fit to be used in
prefabricated construction.

33. Details of New Connector (UHPC-steel tube)
Ø Suitable for assembly construction.
Ø Better mechanical properties, such as stiffness and
ductility.
UHPC
steel tube
screw
concrete
slab
glubam
beam

34. Assembly process

35. Compared with dowel and notched
connectors
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
0
20
40
60
80
100
120
140
160
180
ShearForce/kN
Slid/mm
C-3
TR18-40
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
ShearForce/kN
Slid/mm
SC-1-18
TR18-25
TR18-30
TR18-35
TR18-40
notch
UHPC-steel tube
screw
UHPC-steel tube

36. Conclusions
• The UHPC-steel tube connector shows both high shear
stiffness and high ductility.
• The mechanical properties and long-term performance of
composite beams using UHPC-steel tube connectors are worth
further investigation.