Pull-out Resistance of Glued-in Rod Embedded Parallel to Grain in

Laminated Bamboo with Two Edge Distance Variations

Widiya Anistiya K. Rumasoreng

, Karyadi

and Nindyawati

Department of Civil Engineering, Universitas Negeri Malang, Jalan Semarang 5, Malang, Indonesia

Keywords: Bamboo, Glued-in Rod, Pull-out, Two Edge Distance.

Abstract: The purpose of this study is to find the pull-out strength of the glued-in rod embedded parallel to the grain in

laminated bamboo with variations in the two edge distance. An experimental method was used in this research.

The dimensions of the laminated bamboo specimen were 160 mm x Xd mm x 100 mm, where Xd was the

variation of the two edge distance of the steel rod depending on the diameter of the steel rod. The embedded

length of steel rods was 40 mm with a 3 mm thickness of adhesive. The results showed that the smallest two

edge distance of steel rods experience a decrease in the pull-out strength at diameters of 8 mm, 10mm, and

12 mm, were 4d; 3.5d; and 3d, respectively. This study's slip modulus has not been influenced by the two

edge distance of the steel rods. The study concluded that the greater the two edge distance of the steel rods at

the same diameter increases the pull-out strength value. Also, the larger the diameter of the steel rods used

reduces the two edge distance before experiencing a decrease in the value of pull-out strength.

INTRODUCTION

Several studies on laminated bamboo beams and

columns as building construction elements have been

carried out, such as by Karyadi and Susanto (2017)

and Karyadi et al. (2019).

The utilization of laminated bamboo as a building

construction element in beam and column requires the

connector tool's support. There are several types and

materials of connectors that can be used, such as bolts

(Platt & Harries, 2015) and nails (Reynolds et

al.,2016). Another connector that is currently

developed is a glued-in rod. Some researches on the

glued-in rod have been conducted on woods by

(Gattesco et al., 2010); (O'Neill et al., 2017); (Za’ba et

al., 2012); and (Steiger et al., 2006).

However, the study on glued-in rod connection in

laminated bamboo has not been massively carried out

due to its essential connection characteristic. Yan et

al. (2015) studied the effect of depth and diameter of

steel rods on the pull-out strength of glued-in rod

laminated bamboo. Karyadi et al. (2020) explored the

distance effect of the steel rod on one side of the

https://orcid.org/0000-0001-5312-2712

https://orcid.org/0000-0002-4882-1655

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laminated bamboo's outer edge on the pull-out

strength of the glued-in rod connection.

In addition, Karyadi et al. (2019) has also

experimented on thickening walls in hollow cross-

sectional beams of laminated bamboo against

transverse loads with shear damage. With a thin-

walled hollow beam or column cross-section, further

research is required on glued-in rod joints in

laminated bamboo with the influence of the two outer

edges' distance of steel rods. This study examines the

effect of diameter and steel rod distance from two

outer edges on pull-out strength, slip modulus, and

their damage.

The minimum distance of steel rod based on

Timber Design Guide (Buchanan, 2007) regulation is

2.5d, in which it represents the distance between steel

rod to one side of the wood edge. Thus, this research

was conducted to find the minimum steel rod distance

on two outer edges using 2.5d distance as the initial

reference.

Previous researchers have used several formulas

to predict the pull-out strength from the glued-in rod

connection. This experiment used the New Zealand

Timber Design Guide (Buchanan, 2007) formula

K. Rumasoreng, W., Karyadi, . and Nindyawati, .

Pull-out Resistance of Glued-in Rod Embedded Parallel to Grain in Laminated Bamboo with Two Edge Distance Variations.

DOI: 10.5220/0010748200003113

In Proceedings of the 1st International Conference on Emerging Issues in Technology, Engineering and Science (ICE-TES 2021), pages 213-219

ISBN: 978-989-758-601-9

213

presented in Formula (1).

=6,73.K

(





)

0,86





)

1,62





)

0,5

(





)

0,5

(1)

In which Qk represents the pull-out strength (N,

kN), while Kb, Ke, Km are the connector type factor,

epoxy factor, and water level, respectively.

Meanwhile, l is anchor length (mm), d is steel

diameter (mm), h is hole diameter (mm), and e is the

distance of the edge from the centre of the connector

(mm).

The result from the pull-out calculation was also

used to calculate the steel rod slip with formula (2).

∆

−∆

(2)

The ΔL was calculated using the formula (3).

∆=

P.L

(3)

Description:

∆S : Slip (mm)

Y : Increase in total length (mm)

∆L: Increase in steel length (mm) P : Load (N)

Lo : Clamping distance (mm)

AS: Steel cross-sectional area (mm

) E : Steel

elastic modulus (MPa)

The slip rate was used to calculate slip modulus value

(Ks) using the formula (4) (BS EN 26891, 1991).



0,4 F







− d





(4)

Description:

Ks: slip modulus (kN/mm)

Fmax: peak load (kN)

d04: slip at 40% Fmax

d01: slip at 10% Fmax

METHODS (AND MATERIALS)

Petung bamboo (Dendrocalamus Asper) was used as

the laminated bamboo. It was obtained from Malang

Regency, East Java, Indonesia. The Petung bamboo

was 3-5 years in age. It was split into bamboo strips,

5 mm thick and 20 mm wide. The strips were

preserved in a mixture of 1% borax (Na2B4O2), 1%

boric acid (H3BO3), and 98% water for 4 hours. The

strips then were dried until they only had 10–12%

moisture content. It was glued using urea-

formaldehyde type glue with a spread of 268 g/m² and

cold-pressed of 2MPa for ± 4 hours. The process was

conducted until it reached the planned size.

The steps were repeated until the laminated

bamboo beams were formed. Then, they were cut in

160mm length, 100 mm width, and the thickness

following the variations of steel rod distance (Xd) of

2.5d up to 4.5d on the two outer edges (Figure 1).

Each variation had five testing object replicas. The

next step was drilling a hole with a depth of 40mm

and a diameter equal to the steel rod's diameter plus

the adhesive thickness, 3mm. The threaded steel rod

had 350MPa yielding stress with 8 mm, 10 mm, and

12 mm diameters. The steel rod was embedded in the

drilled hole filled with epoxy resin adhesive from

Sikadur 732 brand.

a) Top View.

b) Isometric View.

Figure 1: Test Object.

The glued-in rod's pull-out strength processing took

place at the State University of Malang, Indonesia,

using the Universal Testing Machine (UTM) with

1000kN capacity and 0.1kN accuracy. The slip rate

was measured using a dial gauge with 10mm capacity

and 0.01mm accuracy. Figure 2 shows the pull-out

testing mechanism.

ICE-TES 2021 - International Conference on Emerging Issues in Technology, Engineering, and Science

214

Figure 2: (a) Pull-out testing image. (b) Test configuration:

pull-press.

RESULTS AND DISCUSSION

The moisture content measured on the pull-out test

day was 13.73% based on ASTM D (2003). The

laminated bamboo density based on ASTM D (2014)

is 0.738gr/cm

. The thickness is similar to the

research conducted by Ruschet al. (2019), with the

result of 0.77gr/cm

. The pull-out strength, the

damage types, and the slip modulus rate are explained

separately below.

Pull-out strength of the glued-in rod. The

minimum distance between the steel rod and two

outer edges of laminated bamboo before experienced

pull-out strength reduction for diameter variations of

8mm, 10mm, and 12mm are 4.0d, 3.5d, and 3.0d

respectively, with the pull-out strength of 17.24kN,

19.86kN, and 19.48kN.

A smaller distance between the steel rod and two

outer edges is equal to the smaller surface area of

laminated bamboo that received load and increased

the stress between the glued-in rod area that easily

damaged the laminated bamboo. In this case, it will

be splitting before the glued-in rod reached the

maximum pull-out strength. Table 1 presents the

complete results from the pull-out force.

Figure 3 shows the relation between the edge

distance and load results of pull-out strength from

each diameter variant.

Yan et al. (2010) stated that the glued-in rod's

pull-out strength in laminated bamboo increases

following threaded steel rod diameter and embedded

length. During the test, the steel rod experiences an

upward pull, while the laminated bamboo area

attached to the adhesive produces the opposite

reaction force. The effect of a steel rod diameter

explains its contact area. Therefore, a larger diameter

represents more contact and a more significant

opposite reaction to increasing the pull-out strength.

Table 1: Pull-out test result of glued-in rod.

Rod

Diameter

Edge Distanc

Bounded Area

(As)

Total

Samples

Mean of ma

Load (P)

Standard

Deviation

Shear Strengt

(Fs = P/As)

(mm) (mm) (mm

) (kN) (kN) N/mm

8 2.5d 1,759.29 5 15.30 0.726 8.697

8 3.0d 1,759.29 5 15.50 0.738 8.810

8 3.5d 1,759.29 5 15.74 0.737 8.947

8 4.0d 1,759.29 5 17.24 0.428 9.799

8 4.5d 1,759.29 5 17.52 0.589 9.959

10 2.5d 2,010.62 5 16.30 2.121 8.107

10 3.0d 2,010.62 5 17.33 1.135 8.617

10 3.5d 2,010.62 5 19.86 0.896 9.878

10 4.0d 2,010.62 5 20.00 0.216 9.947

10 4.5d 2,010.62 5 19.88 0.576 9.888

12 2.5d 2,261.95 5 17.20 1.007 7.604

12 3.0d 2,261.95 5 19.48 1.268 8.612

12 3.5d 2,261.95 5 20.00 0.819 8.842

12 4.0d 2,261.95 5 19.78 1.482 8.745

12 4.5d 2,261.95 5 22.76 0.776 10.069

Pull-out Resistance of Glued-in Rod Embedded Parallel to Grain in Laminated Bamboo with Two Edge Distance Variations

215

Figure 3: Relation between loads and edge distance.

Based on Figure 4 (a), (b), (c), the pull-out

strength of the glued-in rod embedded parallel to

grain in this study is higher than the predicted strength

based on the New Zealand Timber Design

(Buchanan, 2007). The differences occur because

several factors, such as the New Zealand Timber

formula, are supposed for wood material. The utilized

(a) 8mm Diameter.

b) 10mm Diameter.

Figure 4: The comparison charts on pull-out strength

values.

procedure is for pull-out strength of the various

distances between the steel rod and one outer edge,

while this research adopts two outer edges. This

research referred to the New Zealand Timber Design

(Buchanan, 2007) formula since there is no unique

formula to predict the glued-in rod connection in

laminated bamboo.

Although the pull-out strengths are different, the

trend line between the results and predictions has a

similar pattern. A more considerable distance from

the steel rod on the outer edge increases the glued-in

rod pull-out strength.

Glued-in Rod Joint Damage Types. Based on Table

2, 30 specimens among 75 testing objects experience

damage from the bond between the adhesive with

bamboo or the adhesive with threaded rod steel (type

II). The 45 testing objects experience damage when

the steel rods are pulled out along with the laminated

8 mm diameter 10 mm diameter 12 mm diameter

2.5d 3d 3.5d

Edge Distance

4d 4.5d

Mean of maximum load (kN)

ICE-TES 2021 - International Conference on Emerging Issues in Technology, Engineering, and Science

216

bamboo around the adhesive (type III) (Faghani et al.,

2013). All objects in all diameter variations encounter

splitting when they are in 2.5d distance between the

steel rod and two outer edges. Figure 5 shows the

types of failure.

(a) (b) (c)

Figure 5: (a) the steel rod got pulled along with the

laminated bamboo, (b) bond damage between adhesive and

steel rod or bamboo, (c) splitting damage in 2.5d distance

variant.

According to (Gattesco et al., 2010), splitting

damage is most frequently happened and more

fragile. That study suggested that the minimum

distance of steel rod to avoid splitting on wood was a

2.3 diameter steel rod on the outer edge. In this

research, the minimum distance to prevent splitting is

3.5d between two outer edges of laminated bamboo.

Table 2: Types of Failure.

Rod

iamete

)

Edge

Distance

Total

Samples

Types of Failure

(mm) (xd)

III Splitting

8 2.5d 5

1 5

8 3.0d 5

2 2

8 3.5d 5

3 1

8 4.0d 5

8 4.5d 5

10 2.5d 5

4 5

10 3.0d 5

3 1

10 3.5d 5

2 1

10 4.0d 5

10 4.5d 5

12 2.5d 5

5 5

12 3.0d 5

12 3.5d 5

5 1

12 4.0d 5

12 4.5d 5

Slip Modulus. Figure 6 presents the relation chart

between load and slip, which shows that the distance

of the steel bar to the outer edge does not significantly

affect the value of the slip modulus. In Table 3, the

average slip modulus calculated using formula (4)

ranges from 4.042-7.686kN/mm.

Figure 6: Load and slip relationship.

Pull-out Resistance of Glued-in Rod Embedded Parallel to Grain in Laminated Bamboo with Two Edge Distance Variations

217

Table 3: Slip modulus calculation results.

Rod Diameter Edge Distance

Initial Length

(Lo)

Mean of Max

Load (P ult)

∆S Ultimate

Loa

Slip Modulus

(mm) (mm) (mm) (kN) (mm) (kN/mm)

8 2.5d 137.0 15.30 2.530 5.742

8 3.0d 137.2 15.50 2.783 4.537

8 3.5d 140.2 15.74 2.988 5.023

8 4.0d 136.4 17.24 3.361 4.553

8 4.5d 135.2 17.52 3.093 4.921

10 2.5d 135.4 16.30 2.967 5.291

10 3.0d 135.4 17.33 3.267 4.335

10 3.5d 133.2 19.86 3.200 4.901

10 4.0d 135.4 20.00 3.364 4.962

10 4.5d 134.4 19.88 3.647 4.042

12 2.5d 135.0 17.20 3.018 5.801

12 3.0d 134.8 19.48 2.717 7.686

12 3.5d 134.2 20.00 3.228 6.103

12 4.0d 134.2 19.78 3.092 6.194

12 4.5d 135.8 22.76 3.210 7.482

Higher pull-out strength and lower slip result in

higher stiffness. Test objects with 8mm and 10mm

diameter show that a higher ultimate load increases

the slip. As presented in Table 2, test objects with

8mm and 10mm variations experience interface

damage between the steel rod and adhesive glue and

induce the rod to be pulled out easily. Meanwhile, the

test object with 12mm diameter variaption

experiences dominant damage in the form of a pulled-

out threaded rod along with the bamboo surface

around the epoxy adhesive glue. This circumstance

makes it difficult for the steel rod to move, affecting

the slip value.

Figure 6 also illustrates that all variations have the

same trend line. Thus, all the decrease during testing

was brittle, in which the glued-in rod undergoes

reduction without any decrease in the load, gradually,

right after peak load.

CONCLUSIONS

Based on the results of this study, some conclusions

have been drawn. First, the minimum distance

between the steel rod and two outer edges laminated

bamboo before the glued-in rod that experiences a

reduction in the pull-out strength in diameter

variations of 8mm, 10mm, and 12mm are 4.0d, 3.5d,

and 3.0d, respectively. Second, the Failure types that

occurred on 75 test objects are brittle. In the same

diameters, a smaller distance between the steel rod

and two outer edges of laminated bamboo is equal to

a higher chance of splitting damage. In this research,

the minimum distance of the steel rod to avoid

splitting damage is 3.5d. Third, the distance between

the steel rod and two outer edges of laminated

bamboo carries no influence on the value of slip

modulus.

ACKNOWLEDGEMENT

This article is part of a Basic Research of Higher

Education Excellence scheme funded by The

Ministry of Research and Technology in the Republic

of Indonesia in 2021.

REFERENCES

ASTM (American Society for Testing and Materials), 2003.

Standard Test Methods for Direct Moisture Content

Measurement of Wood and Wood-Base Materials.

Annual Book of ASTM Standards, Vol. 04:10: D 4442-

92 Section 2, West Conshohocken, PA, United States.

ASTM (American Society for Testing and Material), 2014.

Standard Test Methods for Density and Specific

Gravity (Relative Density) of Wood and Wood-Based

Materials. Annual Book of ASTM Standards, Vol.

04:10: D 2395-14 Section 6, West Conshohocken, PA,

United States.

BS EN 26891, 1991. Timber Structures-Joints Made with

Mechanical Fasteners-General Principles for the

ICE-TES 2021 - International Conference on Emerging Issues in Technology, Engineering, and Science

218

Determination of Strength and Deformation

Characteristics. European Committee for

Standardization (CEN), Brussels, Belgium.

Buchanan, A. H. 2007. Timber Design guide, 3

Edition.

New Zealand: New Zealand Timber Industry

Federation.

Faghani, P. 2013. Experimental and numerical

investigations of pull-out strength of timber joints with

glued-in rods. Thesis, Columbia: The University of

British Columbia.

Gattesco, N., A. Gubana and M. Buttazzi, 2010. Pull-out

strength of bar glued-in-timber joints. Proceeding of

11th Word Conference on Timber Engineering

(WCTE). Trentino, Italy, Jun. 20-24, pp: 1194-1200.

Karyadi and P. B. Susanto, 2017. Mechanical characteristics

of box-section beam made of sliced-laminated Asian

bamboo (Dendrocalamus asper) in bending failure

mode under transversal load. Proceeding of AIP

Conference, American Institute of Physics, Vol. 1887,

ID: 020062.

Karyadi, Basuki, E. W. A., Susanto, P. B, & Nindyawati.

2019. Sidewall Thickening as Strengthening for Box-

Section Laminated Bamboo Beam under Transverse

Load in Shear Failure Mode. Research Journal of

Applied Sciences, Engineering and Technology. 16

(129-134). Dari https://doi.org/10.1063/1.5003545

Karyadi, Prayogo, B., Nindyawati., Susanto, P. B,. Pull-out

Resistance Parallel to Grain of Threaded Steel Rod

Glued-in Glulam with Edge Distance Variation, 2020.

Research Journal of Applied Sciences, Engineering and

Technology. 17 (1):1-6, 2020

O'Neill, C., D. McPolin, S.E. Taylor, A.M. Harte, C.

O'Ceallaigh and K.S. Sikora, 2017. Timber moment

connections using glued-in basalt FRP rods. Constr.

Build. Mater., 145: 226-235.

Platt, S., & Harries, K.A., 2015. Strength of Bolted Bamboo

Laminate Connections. Proceeding 16

NOCMAT,

Winnipeg, Canada.

Rusch, F., R. Trevisian., E. Hillig., E.C. Mustefaga, 2019.

Physical-mechanical Properties of Laminated Bamboo

Panels.e-ISSN 1983-4063. V-49

Steiger, R., E. Gehri and R. Widmann, 2006. Pull-out

strength of axially loaded steel rods bonded in glulam

parallel to the grain. Mater. Struct., 40: 69-78.

Yan, Y., H. Liu, X. Zhang and Y. Huang, 2016. The effect

of depth and diameter of glued-in rods on pull-out

connection strength of bamboo glulam. J. Wood Sci.,

62: 109-115.

Yeboah, D., S. Taylor, D. McPolin and R. Gilfillan, 2013.

Pull-out behaviour of axially loaded Basalt Fibers

Reinforced Polymer (BFRP) rods bonded

perpendicular to the grain of glulam elements. Constr.

Build. Mater., 38(5): 962-969.

Za'ba, N., Ibrahim, A., & Ahmad, Z., 2012. Bond Strength

of Glued-in Rods in Malaysian Tropical Timber as

Influenced by Adhesive, Diameter, and Glue Line

Thickness. ASEAN Journal on Science and

Technology for Development, 29(1):13-20.

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