MODELING OF THE ELASTIC PROPERTIES OF LAMINATED STRAND LUMBER

Author

Haiyang Zhang, Xiaoning Lu*
Nanjing Forestry University, College of Wood Science and Technology Nanjing, China
(Received November 2012)

ABSTRACT
Laminated strand lumber as a structural composite lumber material has gained remarkable acceptance in light commercial and residential construction. A model was established to predict the elastic properties of the laminated strand lumber. The model assumes homogeneity in each panel layer to allow for multiple-layer panels to be simulated. The elastic constants of each panel layer were calculated by the modified elasticity energy principle in which the wood strands were regarded as the reinforced phase and the adhesive resin as the matrix. The panels with different structures were manufactured to verify the model. The predictions of the model match well with the measured results. The model may be helpful in design and manufacture of the laminated strand lumber.
KEYWORDS: Wood based composites, laminated strand board, elasticity energy principle; laminated theory, engineering constants.

INTRODUCTION
Laminated strand lumber (LSL) is a structural wood-based composite material consisting of oriented wood strands that are spray blended with adhesives and hot-compressed to form panels. The thickness of the wood strands for producing LSL is 0.5 to 2 mm and the length is shorter than 300 mm. Low density woods are the preferred raw material which permits property enhancement through densification. It can be produced from smaller diameter and low quality trees thereby reducing our dependence on old growth forests. Because LSL sometimes has stronger mechanical properties and less variability than solid lumber, it is an attractive alternative to solid sawn lumber and has gained a lot of research interest in many areas, including basic production technology, property improvement and product development (Moses et al. 2003, Denizli-Tankut et al. 2004, Josčák et al. 2006, Me et al. 2008, Ferraz et al. 2009, Ma and Yang 2011). ) 

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Steel‐Reinforced Glued Laminated Timber

Author

William M. Bulleit, Member, ASCE; L. Bogue Sandberg, Member, ASCE; and Greg J. Woods

- See more at: http://ascelibrary.org/doi/abs/10.1061/(ASCE)0733-9445(1989)115%3A2(433)#sthash.fWbsHnEt.dpuf

Abstract

A possible candidate for replacement of tension laminations in glulam beams is examined. The replacement is a composite of concrete‐reinforcing steel embedded in oriented flakeboard. Pullout tests were used to select the best of three possible furnishes for the composite. After this selection, 2in.6in.×9ft(50.8mm×152.4mm×2.74m)$2\mathrm{in}\text{.}6\mathrm{in}\text{.}9\mathrm{ft}50.8\mathrm{mm}152.4\mathrm{mm}2.74m$ beams were fabricated. Control beams with no reinforcing and beams with one lamina replaced with the steel‐wood composite were tested. The beams were tested both dry (50% RH) and wet (90% RH). The dry beams exhibited increases in stiffness of 24% and 32% and increases in ultimate moment capacity of 29% and 30% for one number 3 or number 4 bar, respectively, in the beam. The wet beams also showed increases in stiffness on the order of 30% but showed no significant increases in strength. This lack of reinforcing effect is likely to be a combination of increased steel stress due to reduced wood modulus of elasticity with increased moisture content and decreased flakeboard internal bond strength due to increased moisture content.

 - See more at: http://ascelibrary.org/doi/abs/10.1061/(ASCE)0733-9445(1989)115%3A2(433)#sthash.fWbsHnEt.dpuf

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Analysis of Mechanically Laminated Timber Beams Using Shear Keys

Author

Joseph F. Miller and William M. Bulleit, M.ASCE

- See more at: http://ascelibrary.org/doi/abs/10.1061/(ASCE)ST.1943-541X.0000273#sthash.pFRPdgTz.dpuf

Abstract

Small timber layers can be mechanically laminated into a larger timber cross section using shear keys to prevent slip between the layers. These mechanically laminated beams are commonly referred to as keyed beams and their use has a strong historical precedence. Current building codes and design standards do not provide adequate guidelines for the analysis of keyed beams. This project examined the applicability of an interlayer slip model to predict the partially composite behavior of the keyed beams. Solutions to the interlayer slip model for common loading configurations were developed, as were stiffness parameters for the semirigid wooden shear keys used to provide composite action. Small and full-scale testing of timber components was also performed to verify the interlayer slip model’s ability to predict the stiffness of specific keyed beam specimens. A comparison of the interlayer slip model to historical keyed beam test data was also conducted. The interlayer stiffness model, as well as the analytical shear key stiffness parameters, was able to accurately predict both the behavior for the full-scale keyed beams tested specifically for this research as well as the historic keyed beam behavior. Shear key configuration, moisture content, and clamping connector stiffness all played significant roles in the actual keyed beam stiffness. - See more at: http://ascelibrary.org/doi/abs/10.1061/(ASCE)ST.1943-541X.0000273#sthash.pFRPdgTz.dpuf

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Assessing the Ability of Ground-Penetrating Radar to Detect Fungal Decay in Douglas-Fir Beams

Author: Senalik, Christopher Adam; Wacker, James; Wang, Xiping; Jalinoos, F.; 

Date: 2016

Source: 25th Research Symposium, New Orleans (110-116). Columbus, OH: American Society for Nondestructive Testing, Inc. 7 p. 

Publication Series: Paper (invited, offered, keynote)

Description: This paper describes the testing plan and current progress for assessing the efficacy of using ground-penetrating radar (GPR) to detect fungal decay within Douglas-fir beams. Initially, the beams were assessed using a variety of physical, mechanical, and nondestructive evaluation (NDE) test methods including micro-resistance drilling, Janka hardness, ultrasonic transmission, and GPR. After initial baseline assessment, beams were inoculated with brown rot fungus, Fomitopsis pinicola, and exposed to above-ground conditions approximately 25 miles (40 km) north of Gulfport, Mississippi, USA. Beam specimens will be removed from the exposure site at six-month intervals and scanned using GPR to detect and assess interior rot. After GPR scanning, micro-resistance drilling and ultrasonic transmission testing will be performed. Finally, the beams will be cut into 2-in. segments for Janka hardness testing, which will give the most definitive information regarding the spread of the brown rot fungus throughout the beams. The GPR scans will be compared to the hardness testing, micro-resistance drilling, and ultrasonic testing results to evaluate the ability of GPR to detect interior rot within the beams.

Keywords: Ground-penetrating radar, fungus, brown rot, Douglas-fir, sawn timber, glulam

Publication Notes:

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• This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.

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Citation:

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Senalik, C.A.; Wacker, J.P.; Wang, X.; Jalinoos, F. 2016. Assessing the Ability of Ground-Penetrating Radar to Detect Fungal Decay in Douglas-Fir Beams. In: 25th ASNT Research Symposium: Summaries and Abstracts. Paper presented at 25th Research Symposium, New Orleans (110-116). Columbus, OH: American Society for Nondestructive Testing, Inc. 7 p.

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Fruits from the forest and the fields: forest conservation policies and intersecting social inequalities in Burkina Faso’s REDD+ program

While gender issues are becoming increasingly integrated in international environment and development policies, the simplistic manner in which they are treated holds scant promise for real change. In the Reducing Emissions from Deforestation and Forest Degradation (REDD+) program in Burkina Faso, women are targeted in projects promoting non-timber forest product commercialisation aimed to incentivise forest conservation. Such policies are often based on essentialist assumptions about what men and women do, ignoring that social relations of inequality need to be understood in context. Drawing on intersectional theory this study analyses REDD+ documents, and data about resource use in two villages in Burkina Faso, showing how the participatory approach in Burkina’s REDD+ program is unlikely to encourage currently marginalised voices to be heard in existing forest management organisations. Rather, the lack of acknowledgement of intersecting relations of inequality leads to crucial aspects of NTFP resource use being overlooked, and risks leading to increased marginalisation of certain groups.

Authors: Westholm, L.

Topic: climate change, non-wood forest products, gender, forest conservation

Geographic: Burkina Faso

Publication Year: 2016

ISSN: 1465-5489

Source: International Forestry Review 18(8): 511-521

DOI: https://doi.org/10.1505/146554816820127578

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Forest use in Nicaragua: Results of a survey on gendered forest use, benefits and participation

Key results

• Generalizations about gender and forests are misleading; detailed, comparative studies are needed to understand important contextual differences not only among world regions but also, as demonstrated here, within countries, among different cultures.
• Gender biases lead men to underestimate women’s work related to forests and overestimate their benefits and role in decision making, relative to women’s own estimates.
• In Nicaragua, forest resources, particularly firewood, are important for the vast majority of rural households studied; indigenous households, as well as indigenous women specifically, use and benefit from a much larger variety of forest resources than non-indigenous communities.
• Of all the forest products mentioned by respondents, men extract more than women, except for craft materials in some locations.
• Indigenous women are much more involved in the sale of forest products than non-indigenous women and are more likely to control the income from the products they sell.

Authors: Larson, A.M.; Flores, S.; Evans, K.

Topic: gender, forest resources, indigenous people

Geographic: Nicaragua

Series: CIFOR Infobrief no. 162

Pages: 6p.

Publisher: Bogor, Indonesia, Center for International Forestry Research (CIFOR)

Publication Year: 2016

DOI: 10.17528/cifor/006345

This work is licensed under a Creative Commons Attribution 4.0 International License.

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Guinea pig or pioneer: Translating global environmental objectives through to local actions in Central Kalimantan, Indonesia’s REDD+ pilot province

Many difficulties have arisen from top-down approaches to the design and implementation of global environmental initiatives. The concept of translation and other analytical features of Actor-Network Theory (ANT) can offer a way of conceptualising these difficulties and their practical effects. By translation, we refer to what happens in-between the formulation of international goals and the results of implementation, and more specifically, relations and negotiations within this broader process. We examine several aspects of translation in the case of Reducing Emissions from Deforestation and Forest Degradation (REDD+), a prominent global environmental initiative. Using an ethnographic approach, we explore local responses in Central Kalimantan province, Indonesia, to REDD+ ideas and goals that originate at international and national levels. Following selection in 2010 as the official REDD+ pilot province, Central Kalimantan became a site for the convergence of actors and projects with varied sources of funding. The study identifies a central tension that emerged between an initial vision of Central Kalimantan as a pioneer, and local concerns about being used as an experimental subject or ‘guinea pig’ for the testing of externally designed schemes. Results show that greater flexibility in the design of programs and initiatives is needed, to provide space for local inputs. Implementation should pay attention to how local actors are included in planning processes that inform decision-making at higher jurisdictional levels. To bring about intended changes in land use, programs like REDD+ need to extend beyond a focus on short-term projects and targets, to instead emphasise long-term investments and forms of collective action that support learning.

Authors: Sanders, A.J.P.; da Silva Hyldmo, H.; Prasti H., R.D.; Ford, R.M.; Larson, A.M.; Keenan, R.J.

Topic: climate change, land use, community forestry

Geographic: Indonesia

Publication Year: 2017

ISSN: 0959-3780

Source: Global Environmental Change 42: 68-81

DOI: 10.1016/j.gloenvcha.2016.12.003

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Host country governance and the African land rush: 7 reasons why large-scale farmland investments fail to contribute to sustainable development

The large social and environmental footprint of rising investor demand for Africa’s farmland has in recent years become a much-examined area of enquiry. This has produced a rich body of literature that has generated valuable insights into the underlying drivers, trends, social and environmental impacts, discursive implications, and global governance options. Host country governance dynamics have in contrast remained an unexplored theme, despite its central role in facilitating and legitimizing unsustainable farmland investments. This article contributes to this research gap by synthesizing results and lessons from 38 case studies conducted in Ethiopia, Ghana, Nigeria, and Zambia. It shows how and why large-scale farmland investments are often synonymous with displacement, dispossession, and environmental degradation and, thereby, highlights seven outcome determinants that merit more explicit treatment in academic and policy discourse.

Authors: Schoneveld, G.C.

Topic: agriculture, investment, land use, tenure, land management

Geographic: Africa

Pages: 14p

Publication Year: 2016

ISSN: 0016-7185

Source: Geoforum 

DOI: 10.1016/j.geoforum.2016.12.007

This work is licensed under a Creative Commons Attribution 4.0 International License.

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Illegal logging: law enforcement, livelihoods and the timber trade

Threre is limited knowledge available as to the major causes of illegal logging and its impacts on biodiversity, people and livelihoods and national economies, and thus plenty of speculation and action without evidence. It is clear that while illegal logging does have negative impacts, it also, controversially, and perhaps paradoxically, benefits many stakeholders, including local communities. This book examines the key issues including law and enforcement, supply and demand, corruption, forest certification, poverty, local livelihoods, international trade and biodiversity conservation. It includes key case studies from forest-rich hotspots in North, South and Central America, equatorial Africa and Indonesia. While there are clearly no easy answers, this book sorts fact from fiction and explores the many dimensions of the causes, impacts and implications for forests, people, livelihoods and forest policy.

Authors: Tacconi, L.; ed.

Topic: logging,illicit felling,forestry law,forest policy,forests,forest products,corruption,decentralization,property rights,causes,impact,livelihoods,international trade,certification

Pages: 301p.

Publisher: Earthscan, London, UK

Publication Year: 2007

ISBN: 978-1-84407-348-1

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http://www.cifor.org/library/2213/illegal-logging-law-enforcement-livelihoods-and-the-timber-trade/

Decentralisation of administration, policy making and forest management in Ketapang district, West Kalimantan

This study examines the preliminary impacts of Indonesia’s decentralization process on the administration and management of forest resources in Ketapang District, West Kalimantan. The case study is based on field work carried out in mid-2000, using a rapid appraisal methodology. The report covers the impacts of decentralization in three areas, in particular: customary adat communities, oil palm and rubber plantations, and conservation issues related to Gunung Palang National Park. In each of these areas, the authors examine struggles among competing interest groups that have arisen under decentralization. The study finds that with the shift of administrative authority to the district level, the district government in Ketapang tool measures to generate local sources of revenues by issuing large numbers of small-scale timber extraction permits and to ‘legalize’ the transport of timber that had otherwise been harvested illegally. The study also finds that the very limited flow of formal revenues from the Gunung Palang National Park to the district government has encouraged an escalation of illegal logging within the park’s boundaries. It is recommended that the Ketapang district government become more involved in administering the national park to ensure that economic interests of both the district government and local communities are accomodated in the park’s management.

Authors: Soetarto, E.; Sitorus, M.T.F.; Napiri, M.Y.

Topic: decentralization,forest policy,customary law,plantations,oil palms,rubber plants,national parks,illicit logging,conservation,local government,local people,resource management

Geographic: West Kalimantan,Indonesia

Series: Case Studies on Decentralisation and Forests in Indonesia no. Case study 8

Pages: xiii, 55p.

Publisher: CIFOR, Bogor, Indonesia

Publication Year: 2001

ISBN: 979-8764-85-4

DOI: 10.17528/cifor/001441

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