• Journal of the Korean Wood Science and Technology
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• 제48권2호
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• pp.245-252
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• 2020

This study was performed to analyze the mechanical properties of tropical hybrid cross-laminated timber (CLT) with bamboo laminated board as the core layer in order to evaluate the possibility of its use as a CLT material. Bamboo board was used as the core layer and the tropical species Acacia mangium willd., from Indonesia, was used as the lamination in the outer layer. The modulus of elasticity (MOE), modulus of rupture (MOR), and shear strength of the hybrid CLT were measured according to APA PRG 320-2018 Standard for Performance-Rated Cross-Laminated Timber. The results show that the bending MOE of the hybrid CLT was found to be 2.76 times higher than SPF (Spruce Pine Fir) CLT. The reason why the high MOE value was shown in bamboo board and hybrid CLT applied bamboo board is because of high elasticity of bamboo fiber. However, the shear strength of the hybrid CLT was 0.8 times lower than shear strength of SPF CLT.

• Journal of the Korean Wood Science and Technology
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• 제43권1호
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• pp.86-95
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• 2015

본 연구는 기존에 제조되었던 교호집성재의 휨강도의 단점을 보완하고 새로운 특성을 가진 교호 집성재 즉, 합판을 코어로 이용한 집성재가 가진 기계적강도의 효과를 알아보기 위해 수행되었다. 집성재와 합판의 구성 방법, 적층 방향에 따라 그 값을 비교하였으며, 그에 따른 휨강도와 탄성계수를 측정하여 분석한 결과, 중심부를 집성판과 합판을 혼합하여 구성한 합판 코어 집성재의 휨강도(MOR) 값이 59.6% 강도가 향상되어 교호집성재구조 대조군보다는 우수하고, 집성재구조 대조군과는 유사한 강도를 나타냈다. 휨탄성계수(MOE)는 합판 코어 집성재의 구조 및 적층 방향성에 상관없이 모두 집성재구조 대조군과 유사한 MOE 값을 나타냈다. 치수 안정성 실험에서는 합판을 코어에 사용한 합판코어 집성재가 합판 사용으로 인하여, 수축 팽창률 모두 집성재와 교호집성재구조 대조군에 비해서 더 안정적인 것으로 나타났다.

• Earthquakes and Structures
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• 제15권4호
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• pp.351-360
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• 2018

Energy-based methodology is utilized to design novel timber-steel hybrid core wall system. The timber-steel core wall system consists of cross laminated timber (CLT), steel columns, angled brackets and t-stub connections. The CLT wall panels are stiff and strong, and ductility is provided through the steel t-stub connections. The structural system was modelled in SAP2000 finite element program. The hybrid system is explained in detail and validated using first principles. To evaluate performance of the hybrid core system, a 7-story building was designed using both forced-based design and energy based design (EBD) approaches. Performance of the structure was evaluated using 10 earthquakes records selected for 2500 return period and seismicity of Vancouver. The results clearly served as a good example of the benefits of EBD compared to conventional forced based design approaches.

• 한국공간구조학회논문집
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• 제20권2호
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• pp.39-49
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• 2020

In this study, we will develop a hybrid cross-sectional shape of steel inserted type glued-laminated timber that can improve the strength of structural glued-laminated timber and maximize the ductility by using steel plate with excellent tensile and deformation ability. A total of three specimens were fabricated and the flexural performance test was carried out to evaluate the structural performance of the steel inserted type glued-laminated timber. In order to compare the effect of steel inserted glued-laminated timber, one structural glued-laminated timber test specimen composed of pure wood was manufactured. In addition, in order to evaluate the adhesion performance of the steel inserted, one each of a screw joint test specimen and a polyurethane joint test specimen was prepared. As a result, all the specimens showed the initial crack in the finger joint near the force point. This has been shown to be a cause of crack diffusion and strength degradation. The use of finger joints in the maximum moment section is considered to affect the strength and ductility of the glued-laminated timber beam. Polyurethane-adhesive steel inserted glued-laminated timber showed fully-composite behavior with little horizontal separation between the steel plate and glued-laminated timber until the maximum load was reached. This method has been shown to exhibit sufficient retention bending performance.

• Journal of the Korean Wood Science and Technology
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• 제49권1호
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• pp.93-102
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• 2021

In this article, withdrawal resistances of axially loaded self-tapping screws on wood products made by Korean Larch were predicted with existing estimation equation, and compared with experimental test data. The research was required because no design methodology for the withdrawal resistance of self-tapping screw is present in Korean building code (KBC). First, the withdrawal resistance of wood screw was predicted to use the withdrawal design value estimation equation in National Design Specification for Wood Construction (NDS). Second, three types of wood products, solid wood, cross-laminated timber (CLT) and plywood, were utilized for withdrawal test. For decades, various engineered wood products have been developed, especially cross-laminated timber (CLT) and hybrid timber composites such as timber composites of solid wood and plywood. Therefore, CLT and plywood were also investigated in this study as well as solid wood. Finally, the predicted values were compared with experimentally tested values. As the results, the tested values of solid wood and CLT were higher than the predicted values. In contrast, it is inaccurate to predict withdrawal resistance of plywood since prediction was higher than tested values.

• 국제초고층학회논문집
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• 제9권3호
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• pp.221-233
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• 2020

Based on past experiences of natural disasters and fires in Japan, it is stipulated by law that fire-resistant buildings larger than a certain size should be unique in the world. Recent interest in global environmental issues has led to the active introduction of wooden buildings also in Japan, and it is expected that wooden buildings will become larger and higher in size. This paper introduces the background of the development of fire-resistant laminated timber with a "Self-Charring-Stop layer", the contents of this development including other related developments, and the application of these technologies. In addition, towards the realization of much larger and higher buildings in the future, the current problems and issues to be solved are set and the necessity of the future technological development is described. Finally, a conceptual model of wooden high-rise building is proposed, which will be able to be constructed in 2025 by the further technological development.

• Journal of the Korean Wood Science and Technology
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• 제49권4호
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• pp.336-359
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• 2021

본 연구는 고층 목조건축에 사용되는 대형 목재 패널인 CLT의 낮은 rolling shear strength를 개선하기 위해 hybrid CLT의 연구 개발 동향을 분석하였다. 이를 통해 CLT의 국산화를 위한 연구개발 방향에 활용 가능한 기초자료를 마련하고자 하였고, 낮은 rolling shear strength를 향상시키기 위한 방안으로 활엽수 층재 사용, 층재 배열 각도 변화, 구조용 목질복합체의 사용이 주를 이루고 있다. 활엽수 층재는 침엽수 보다 rolling shear strength와 shear modulus 모두 2배 이상의 높은 값을 나타내므로 활엽수 층재 사용 및 미이용 수종의 활용이 가능함을 확인하였다. 층재 배열 각도 변화에 따라 rolling shear stength 1.5배, shear modulus 8.3배, bending stiffness 4.1배 향상되어 층재 배열 각도를 감소시킴으로써 CLT 강도 향상을 확인하였다. 구조용 목질재료는 기존에 강도성능이 확보된 재료로 층재로 사용하였을 때 최대 MOR 1.35배, MOE 1.5배, rolling shear strength 2배 향상되었고, 층재 간의 접착강도 또한 집성재 블록전단강도 기준인 7.0 N/mm²을 확보할 수 있었다. 선행연구결과를 통해 MOE 7.0 GPa, MOR 40.0 MPa 이상의 휨 특성을 가진 구조용 목질재료를 사용하였을 때 강도성능이 향상됨을 확인하였다. 이를 통해 구조용 목질재료 층재 강도 기준으로 판단하였다. rolling shear strength 개선하기 위한 최적의 방법은 기존 규격에 의한 강도값을 가진 구조용 목질재료의 적용이 가장 유리할 것으로 판단하나, 구조용 목질재료의 섬유 배열에 따른 CLT 층재 배열 방향, 층재 간 접착 강도 등에 대한 추가적인 연구가 필요하다.

• 국제초고층학회논문집
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• 제11권3호
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• pp.171-180
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• 2022

Research and development on high-rise or large-scale wooden buildings have been actively conducted both domestically and internationally. The trend of high-rise wooden buildings is driven by increasing awareness of environmental issues. To utilize wooden materials in buildings is believed to lead to the reduction of the environmental impact. On the other hand, Japan is one of the most earthquake-prone countries in the world, and many wooden detached houses have been damaged in past major earthquakes. This paper summarizes the issues that arise in the realization of medium- and high-rise wooden buildings in Japan, and introduces the initiatives that have been seen so far.

• 대한건축학회논문집:구조계
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• 제34권4호
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• pp.3-13
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• 2018

Load bearing capacity of dowel type fasteners loaded perpendicular to the shear plane is determined based on Johansen's yield theory (Johansen, 1949). In case of inclined screws whose axis is no longer perpendicular, the ultimate load of connection increases because of additional axial withdrawal capacity. To calculate load bearing capacity for inclined screws, KBC2016 and Eurocode5 provide design equations using the combination of two effects; axial and bending strength. Although their equations have been validated for a long time, there is still minimal information how to apply them for concrete-CLT joints. Since there are not many test data available, engineers have to make certain assumptions and thus results may look inconsistent in practice. In this paper, authors would like to describe the current approach and assumptions indicated by KBC2016 and Eurocode 5 and how they match the experimental results in terms of shear strength of CLT-concrete connections. To fulfill the objective, several push-out tests were performed on nine different test specimens. Each specimen has different penetration angles and depths. By analyzing load-displacement curves, the maximum shear strength, stiffness, and ductility were obtained. Shear strength values were compared with the current design codes and theoretical equations proposed in this paper. Observations on stiffness and ductility were briefly discussed.