Lateral load carrying capacities of particleboard shear walls made by gluing with timber studs

Abstract

Particleboard shear walls were developed and their lateral load carrying capacities were evaluated. The shear walls were made by connecting particleboards and timber studs with polyurethane (PUR) or nails. Seven types of particleboard shear wall specimens were manufactured by varying the wood species, size of the timber studs, and number of particleboards. The size of the shear wall specimens was 2.4 m × 2.7 m, and the bottom of the shear wall was fixed to the steel frame of the test equipment using hold-downs and angle brackets. As a result, the lateral load carrying capacities of the glued particleboard shear wall (73.4 to 75.6 kN/m) were 3.2 times higher than that of the typical light-frame shear wall and higher than the experimental data of the cross-laminated timber (CLT) wall in the CLT handbook. All glued specimens failed at the hold-down and angle bracket, and there was no damage at the glue layer between a particleboard and timber studs. The shear performance with different combinations of species, stud size, and number of particleboards was not significantly different, and the shear strength of the nailed specimen was approximately 20% lower than that of the glued specimen.

Full Article

Lateral Load Carrying Capacities of Particleboard Shear Walls Made by Gluing with Timber Studs

Sung-Jun Pang,^a Han Shik Lee,^b and Jung-Kwon Oh ^a,c,*

Particleboard shear walls were developed and their lateral load carrying capacities were evaluated. The shear walls were made by connecting particleboards and timber studs with polyurethane (PUR) or nails. Seven types of particleboard shear wall specimens were manufactured by varying the wood species, size of the timber studs, and number of particleboards. The size of the shear wall specimens was 2.4 m × 2.7 m, and the bottom of the shear wall was fixed to the steel frame of the test equipment using hold-downs and angle brackets. As a result, the lateral load carrying capacities of the glued particleboard shear wall (73.4 to 75.6 kN/m) were 3.2 times higher than that of the typical light-frame shear wall and higher than the experimental data of the cross-laminated timber (CLT) wall in the CLT handbook. All glued specimens failed at the hold-down and angle bracket, and there was no damage at the glue layer between a particleboard and timber studs. The shear performance with different combinations of species, stud size, and number of particleboards was not significantly different, and the shear strength of the nailed specimen was approximately 20% lower than that of the glued specimen.

DOI: 10.15376/biores.18.1.1072-1095

Keywords: Particleboard; Shear wall; Wood; Glue; Lateral capacity

Contact information: a: Department of Agriculture, Forestry and Bioresources, Seoul National University, Seoul, Republic of Korea; b: Kyung Min Industrial Co., Ltd., Incheon (Gajwa-dong), Republic of Korea;

c: Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea; * Corresponding author: jungoh@snu.ac.kr

INTRODUCTION

Wood is a bioresource material that can be recycled and reused (Asdrubali et al. 2017). Among the various wood products, particleboard can be made from small-diameter wood, thin-cut wood, or waste wood. Thus, particleboard is an effective method to utilize various biological resources, and various related studies have been reported. De Almeida et al. (2017) made the wood-bamboo-based particleboard and evaluated its mechanical properties. Bekhta et al. (2013) evaluated the properties of the wood-straw-based particleboard. Hashim et al. (2012) evaluated the mechanical properties of particleboard panels manufactured from oil palm. They evaluated the mechanical properties of the new particleboard itself.

Wood products generally have a low environmental impact because of their low carbon emissions and sustainability (Gerilla et al. 2007; Yan et al. 2010; Hafner and Schäfer 2018; Sandanayake et al. 2018; Li et al. 2019; Röck et al. 2020). Wooden buildings use a large amount of wood for a long time, and the use of wood products contributes to the reduction of released carbon when it is incorporated into buildings (Petersen Raymer 2006; Resch et al. 2021). Generally, the CLT is used as a shear wall in mid-and high-rise timber buildings (Polastri et al. 2019; Stazi et al. 2019). The CLT uses a lot of solid wood. Therefore, in Korea, where solid wood is more expensive than concrete, CLT is less economical than reinforced concrete. Particleboard is less expensive than solid wood because it can be made from worthless wood. When particleboard is used as a sheathing panel in a light-frame timber shear wall, bearing damage around nails (Germano et al. 2015) or nail penetration can happen (Yue et al. 2022). These types of shear walls may not be strong enough for use in high-rise buildings.

It is proposed that by the use of an adhesive to attach the particleboard panels to the timber studs, it may be possible to exceed the load capacity that can be achieved with conventional nail connections. The binding function of the adhesive can be extended to the entire area of the shear wall, and experimental studies on actual walls are required to confirm the binding function. In this study, particle shear walls were designed by gluing with timber studs, and their lateral load carrying capacities were evaluated. The lateral load carrying capacities according to species, stud size, number of particleboards, and production methods (adhesive, nail) were analyzed.

EXPERIMENTAL

Materials

Shear wall specimens

To experimentally analyze the binding function of the adhesive to the actual particleboard shear walls, test specimens were prepared by varying the species and the size of timber studs, and the number of particleboards. Additionally, a light-frame timber shear wall and a particleboard shear wall made of nails were also fabricated as a control group.

Table 1 shows the combination of test specimens. Seven types of particleboard shear wall specimens were manufactured by varying the wood species, size of the timber studs, and number of particleboards. The specimen ID in Table 1 indicates the wall configurations. The first letter and number indicate the species and width of timber studs. The second term indicates the connection method between particleboards and timber studs. The letter P and N means polyurethane (PUR) and nail, respectively. In No. 7, the connection between particleboards and studs was reinforced with wooden nails (LIGNOLOC® F60, Mauerkirchen, Austria) because the PUR strength of the PUR may not be sufficient. The third term indicates the number of particleboard layers.

Table 1. Combination of Test Specimens

To compare the lateral load carrying capacities of the particleboard specimens (No. 1 through No. 7) with those of a typical light-frame shear wall, the light-frame shear wall specimen (No. 8) with oriented strand board (OSB) sheathings was prepared. Figure 1 shows the layer combination of test specimens. The thickness of the test specimens depends on the number of boards used, but the width and height are all the same (2400 mm × 2700 mm). One test specimen was produced for each condition.

1. No. 1, No. 2, No. 3, No. 6, and No. 7

1. No. 4

1. No. 5

1. No. 8

Fig. 1. Layer combination of test specimens

Figure 2 shows the particleboard shear wall panels manufactured by Kyung Min Industrial Co., Ltd. (Incheon, Republic of Korea) for prefab construction. Larch laminas (Larix kaempferi Carr.) were used for the timber studs for all specimens except for the No. 2 specimen. The No. 2 specimen used European spruce laminas (Ips typographus L.) for the timber studs. Structural lumber (2nd visual grade, moisture contents: 12 ± 2%) according to NIFoS #2020-3 (2020) was used. The thickness of particleboard (Daesung Wood, Incheon, Republic of Korea) and OSB (rated sheathing grade, Georgia-Pacific LLC, Atlanta, GA, USA) was 15 mm and 11.1 mm, respectively. The PUR adhesive was used to glue the flatwise surface of timber studs and particleboards in No. 1 through No. 7, except for No. 6. The edgewise and end surfaces of each lamina were not glued. For No. 6 and No. 8, 8d nails (2.8 mm in diameter and 76 mm in length) with 150 mm spacing were used to connect the particleboards and timber studs.

Fig. 2. A picture of particleboard shear wall panel

Shear Wall Test

A shear wall test was conducted to evaluate the lateral load carrying capacities of the specimens. Figure 3 shows a view of the cyclic loading test with a particleboard shear wall panel installed. Both sides of the bottom of the shear wall specimens were fixed to the steel frame of the test equipment using commercial hold-down (WHT 340), and angle-bracket (TCN 200) manufactured by Rothoblaas (Cortaccia (TN), Italy). A hold-down was fixed with the steel frame with a washer (WHTBS50) and a bolt (M16 × 50 mm), and fixed with the particleboard shear wall specimen using 20 screws (Ø5.0 × 50 mm). An angle bracket was fixed with the steel frame only with two bolts (M12 × 50 mm) without washers, and fixed with the particleboard shear wall specimen using 30 screws (Ø5.0 × 50 mm).

The aspect ratio of all shear wall specimens was 1.125 (height: 2.7/width: 2.4). Figure 4 shows the configuration of shear wall specimens and the position of the Linear Variable Displacement Transducers (LVDT). Five actual displacements of the shear wall were measured according to ASTM E564-06 (2018). LVDT 1 was used for the actual displacement of the top of specimens. LVDT 2 and LVDT 3 were used for the lateral displacement of the bottom of specimens. LVDT 4 and LVDT 5 were used for the vertical displacements of the specimens. LVDT 6 was used for the diagonal displacement of the specimens.

Fig. 3. Picture of a shear wall test with a specimen installed

The vertical load (50 kN) was applied on top of all specimens using an actuator (244.22G2 model, MTS, Eden Prairie, MN, USA). The lateral cyclic loading was applied according to ISO 16670 load protocol in ASTM E2126 (2009) (Method B) using an actuator (244.31G2 model, MTS, USA). The cyclic frequency was 0.2 Hz and Fig. 5 shows the applied displacement history for the shear wall specimens. Load-displacement curve data were obtained while cyclic loading was applied to each specimen according to the loading protocol. The applied load and corresponding displacements of shear wall specimens were recorded at 0.01-s intervals to plot load-displacement curves.

Fig. 4. Configuration of shear wall test

Fig. 5. Loading protocol (ISO 16670 (2003)) for shear wall test

RESULTS AND DISCUSSION

Light-Frame Timber Shear Wall

Failure mode

Figure 6 shows the failure mode in lateral behavior of the light-frame timber shear wall (No. 8). As displacement increased, the nails connecting the OSB sheathings to the timber studs at the upper edge of the wall gradually withdrew and the heads of the nails penetrated the OSB panels. Eventually, the OSB sheathings were separated from the timber studs, which is a common failure mode in light-frame shear walls (Liu et al. 2020). However, there was no damage to the connectors fixing the wall and the steel frame, until the end of the experiment. This shows that the lateral capacity of the light-frame timber shear wall was governed by the withdrawal resistance of the nails, and the metal products were strong enough to support the lateral capacity.

Fig. 6. Opening of the OSB sheathings due to the withdrawal of nails (No. 8)

Table 2. Mechanical Properties of Particleboard Shear Walls According to Load Protocol (ISO 16670) in ASTM E2126 (2009)