Modelling of Glulam beams pre-stressed by compressed wood

Finite element models were, in the first time, developed to simulate the pre-stressing behaviour of Glulam beams with insertion of compressed wood blocks, which were further used to simulate the structural behaviour of the pre-stressed beams subjected to subsequent destructive bending. Here, both the Glulam and compressed wood were modelled as orthotropic elasto-viscoplastic materials. The moisture-dependent, including spring back, swelling of the compressed wood block and the creep of the Glulam were considered in the modelling. The models developed were validated against the corresponding experimental results, with reasonably good correlation in terms of the free swelling, the precamber, initial stress state of the Glulam beams reinforced and load-deflection relationships. With validated models, further studies were then undertaken to investigate effects of the thickness, depth and spacing of compressed wood blocks on the precamber, initial bending stiffness and ultimate load carrying capacity of the beams pre-stressed. The results indicate that there are significant enhancements on the precamber (up to 1/288 of the deflection/span ratio), the initial bending stiffness (up to 23.8%) and the ultimate load carrying capacity (up to 10.4%

EXPERIMENTAL STUDY OF LOCAL SOLID WOOD POST-FIRE BEHAVIOUR

When wood structures are exposed to high temperatures, they will decompose to provide a char layer and pyrolysis zone, an insulating material that inhibits further degradation. This experimental study aims to determine the char thickness and pyrolysis of solid wood exposed to fire for 30, 45, and 60 minutes. The post-fire shear strength has also been evaluated. The solid woods were locally from Nusa Tenggara Island, namely Jati Putih, Bajur, and Rajumas. According to the Indonesian National Standard of the heating curve for structures, the temperature growth was SNI-1741: 2008. Obtained The char layer's highest average thickness was within 60 minutes of combustion with the highest temperature of 1055oC. The char layer for Jati Putih, Bajur, and Rajumas are 2.12 mm, 7.89 mm, and 6.53 mm. Meanwhile, the pyrolysis layers are 8.78 mm, 9.13 mm, and 14.82 mm, respectively, for Jati Putih, Bajur, and Rajumas. Besides, the post-fire shear strength of all wood species shows an increase in shear strength in the core. Wood can still sustain the load during a fire because there is a char layer preventing the core section from immediately exposed to the fire.  

A cost-efficient method to assess carbon stocks in tropical peat soil

Estimation of belowground carbon stocks in tropical wetland forests requires funding for laboratory analyses and suitable facilities, which are often lacking in developing nations where most tropical wetlands are found. It is therefore beneficial to develop simple analytical tools to assist belowground carbon estimation where financial and technical limitations are common. Here we use published and original data to describe soil carbon density (kgC m<sup>−3</sup>; C<sub>d</sub>) as a function of bulk density (gC cm<sup>−3</sup>; <i>B</i><sub>d</sub>), which can be used to rapidly estimate belowground carbon storage using <i>B</i><sub>d</sub> measurements only. Predicted carbon densities and stocks are compared with those obtained from direct carbon analysis for ten peat swamp forest stands in three national parks of Indonesia. Analysis of soil carbon density and bulk density from the literature indicated a strong linear relationship (C<sub>d</sub> = <i>B</i><sub>d</sub> × 495.14 + 5.41, <i>R</i><sup>2</sup> = 0.93, <i>n</i> = 151) for soils with organic C content > 40%. As organic C content decreases, the relationship between C<sub>d</sub> and <i>B</i><sub>d</sub> becomes less predictable as soil texture becomes an important determinant of C<sub>d</sub>. The equation predicted belowground C stocks to within 0.92% to 9.57% of observed values. Average bulk density of collected peat samples was 0.127 g cm<sup>−3</sup>, which is in the upper range of previous reports for Southeast Asian peatlands. When original data were included, the revised equation C<sub>d</sub> = <i>B</i><sub>d</sub> × 468.76 + 5.82, with <i>R</i><sup>2</sup> = 0.95 and <i>n</i> = 712, was slightly below the lower 95% confidence interval of the original equation, and tended to decrease C<sub>d</sub> estimates. We recommend this last equation for a rapid estimation of soil C stocks for well-developed peat soils where C content > 40%

A cost-efficient method to assess carbon stocks in tropical peat soil

Estimation of belowground carbon stocks in tropical wetland forests requires funding for laboratory analyses and suitable facilities, which are often lacking in developing nations where most tropical wetlands are found. It is therefore beneficial to develop simple analytical tools to assist belowground carbon estimation where financial and technical limitations are common. Here we use published and original data to describe soil carbon density (kgC m⁻³; C[subscript d]) as a function of bulk density (gC cm⁻³; B[subscript d]), which can be used to rapidly estimate belowground carbon storage using B[subscript d] measurements only. Predicted carbon densities and stocks are compared with those obtained from direct carbon analysis for ten peat swamp forest stands in three national parks of Indonesia. Analysis of soil carbon density and bulk density from the literature indicated a strong linear relationship (C[subscript d] = B[subscript d] × 495.14 + 5.41, R² = 0.93, n = 151) for soils with organic C content > 40%. As organic C content decreases, the relationship between C[subscript d] and B[subscript d] becomes less predictable as soil texture becomes an important determinant of C[subscript d]. The equation predicted belowground C stocks to within 0.92% to 9.57% of observed values. Average bulk density of collected peat samples was 0.127 g cm⁻³, which is in the upper range of previous reports for Southeast Asian peatlands. When original data were included, the revised equation C[subscript d] = B[subscript d] × 468.76 + 5.82, with R² = 0.95 and n = 712, was slightly below the lower 95% confidence interval of the original equation, and tended to decrease C[subscript d] estimates. We recommend this last equation for a rapid estimation of soil C stocks for well-developed peat soils where C content > 40%

Denial of long-term issues with agriculture on tropical peatlands will have devastating consequences

Non peer reviewe

Denial of long-term issues with agriculture on tropical peatlands will have devastating consequences

Lette