In this study, we have conducted earthquake monitoring on a timber Buddhist temple constructed in 1825. Between 2008 and 2019, 75 strong motion were recorded. The maximum response acceleration was ...recorded during the 2011 Tohoku earthquake, Japan. From the long-time monitoring, the influence by time due to deterioration and exterior force was expected, but the natural frequency of vibration/stiffness did not show any fluctuation in our 12 years of measurement. There was a strong correlation with the natural logarithm of the maximum relative displacement, reflecting the non-linear elastic characteristics of timber structures. However, the natural frequencies of vibration were 10-20% higher in the summer than in the winter, when the climate was hot and humid. The effect of moisture content on the mechanical properties of wood was also investigated and an idealized relationship between the maximum relative displacement and the normalized natural frequency of vibration by MC was proposed.
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BFBNIB, NUK, PILJ, SAZU, UL, UM, UPUK
This study focused on the comparison of the bonding quality of European beech (Fagus sylvatica L.) and English oak (Quercus robur L.), due to variability of moisture content (MC) in the wood. ...Hardwood species as a material, often yield a more difficult drying process, which can cause problems between various MC in the process of bonding. Specimens were bonded in two groups of MCs: 10/10% (control) and 6/14%. After reaching the equilibrium MC in standard conditions, specimens were cut into sample dimensions. Afterward the specimens were tested for bonding quality according to the EN 13354. In general, there is increase of the bonding quality for both hardwood species in different MC specimens. Statistically significant increase was notable in oak. With exception of the MUF adhesive, there were statistical difference between control and 6/14% MC group for oak.
In tropical countries, such as Thailand, the variation of tree moisture content can be significant based on seasonal variations in rainfall. Pulp mill operation optimization accounting for wood ...moisture variation was used to determine optimal operation conditions and minimize production cost. The optimization models were built using empirical modeling techniques with simulated data from the IDEAS software package. Three case studies were performed. First, a base case of nominal annual operation at a fixed production rate was used to calculate production cost that varies with wood moisture content. The second case is annual optimization where production was allowed to vary monthly over an annual cycle to minimize production cost. For the third case, real-time optimization (RTO) was used to determine optimal production rate with the wood moisture content varying every 3 days. The rolling horizon approach was used to schedule production to keep inventory levels within bounds and with a penalty applied to deviations from the annual expected values of inventory. The advantage of RTO in accounting for moisture content variation was confirmed by annual production costs results simulated for 20 years. These results statistically demonstrated that the overall cost was reduced compared to the second case of monthly production targets.
As the tree age increases, the formation of heartwood takes place in the central part of the tree. Since there is a large difference in the moisture content between sapwood and heartwood in conifers, ...the proportion of heartwood expressed in percentage is one of the most important factors influencing the average moisture of trunk wood. The aim of the research was to find out the changes in parameters of heartwood proportion and the changes in average trunk wood moisture parameters, depending on the age of the tree. To evaluate and compare the heartwood proportion in pine and spruce trunk and its moisture, sample plots were established throughout the territory of Latvia in 2011. These sample plots were established in stands of different ages (37-143 years). The total number of sample plots was 61-29 for pines with 246 sample trees and 32 sample plots for spruces with 270 sample trees. With the increase in the tree age from 60 to 140 years, the heartwood proportion increases and the average moisture content of trunk wood decreases. With an increase of the heartwood proportion in pine from 18% to 39%, the average moisture of trunk wood decreases from 108% to 86%, but with an increase of the heartwood proportion in spruce from 30% to 49%, the average moisture content of trunk wood decreases from 107% to 81%.
One of the natural properties of wood and wood-based materials is their soaking capacity (hygroscopicity). The moisture content of wood and building constructions of wood and wood based ...materials significantly influences the service life and reliability of these constructions and buildings. The equilibrium weight moisture content of built-in wood corresponding to temperature/moisture conditions inside the cladding has therefore a decisive influence on the basic requirements placed on building constructions. The wood in wooden frame cladding changes its moisture content depending on temperature and moisture conditions of the environment it is built into. The water vapor condensation doesn’t necessarily have to occur right in the wooden framework of the cladding for the equilibrium moisture content to rise over the level permissible for the reliable function of a given construction. In spite of the fact that the common heat-technical assessment cannot be considered fully capable of detecting the effects of these factors on the functional reliability of wood-based constructions and buildings, an extension has been proposed of the present method of design an assessment of building constructions according to the ČSN 73 0540 standard regarding the interpretation of equilibrium moisture content in relation to the temperature/moisture conditions and their time behavior inside a construction.
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