ANALYSIS OF SOUND SPEED IN LONGITUDINAL DIRECTION AT REFERENCE MOISTURE CONTENT (w = 12 %) IN SAWMILL ASSORTMENTS (FAGUS SYLVATICA, L.)

Akustika ◽  
2020 ◽  
pp. 45-50
Author(s):  
Alena Rohanová
Keyword(s):  
Moisture Content ◽  
Modulus Of Elasticity ◽  
Dynamic Modulus ◽  
Sound Speed ◽  
Longitudinal Direction ◽  
Structural Timber ◽  
Sound Speeds ◽  
Dynamic Modulus Of Elasticity ◽  
Round Timber

This paper explores the analysis of sound speeds in the longitudinal direction and their reduction to the reference moisture content w = 12 %. The sound speed cw was determined with Sylvatest Duo device. Moisture content of beech sawmill assortments (round timber: N = 16, logs: N = 2 × 16, structural boards: N = 54) in the range of 12 – 72 % was measured. For the analysis purposes, the sound speed was converted to reference conditions (c12, uref = 12%). A second-degree polynomial (parabola) with a regression equation of the form: c// = 5649 - 27,371 × w + 0.0735 × w2 was used to convert cw to c12, and correction of measured and calculated values was used as well. The sound speeds c12 in sawmill assortments (c12,round, c12,log, c12,board) were evaluated by linear dependences. Dependence was not confirmed for c12,round and c12,board1 (r = 0.168), in contrast for c12,round and c12,log2 the dependence is statistically very significant (r = 0.634). The results of testing showed that the most suitable procedure for predicting quality of structural timber is the first step round timber – log2, the second step: log2 - board2. More exact results of the construction boards were obtained from log2 than from log1. The sound speed is used in the calculation of dynamic modulus of elasticity (Edyn). EN 408 mentions the possibility of using dynamic modulus of elasticity as an alternative method in predicting the quality of structural timber.

scholarly journals Applying Machine Strength Grading System to Round Timber Used in Hydraulic Engineering Works

Forests ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 281
Author(s):  
Michela Nocetti ◽  
Giovanni Aminti ◽  
C. Brand Wessels ◽  
Michele Brunetti
Keyword(s):  
Modulus Of Elasticity ◽  
Dynamic Modulus ◽  
Acoustic Velocity ◽  
Hydraulic Engineering ◽  
Raw Material ◽  
Dynamic Modulus Of Elasticity ◽  
Sawn Timber ◽  
Mechanical Selection ◽  
Round Timber ◽  
Selection Of

Round timber is often used for hydraulic engineering works, but the strength grading of round logs is not as well developed as that of sawn timber. The advantages of using defined strength classes, as well as the proper selection of the raw material, could be applicable to hydraulic works as well. In this study, the methods and rules developed for sawn timber were applied to the mechanical selection of oak round logs, paying particular attention to the issue of the simplicity of grading operations and the moisture content of the timber. Both the acoustic velocity and dynamic modulus of elasticity of oak logs were measured with different instruments before performing destructive bending tests; machine settings were derived for both properties and dry and wet grading operations were simulated to compare efficiency. The use of the dynamic modulus of elasticity makes machine grading more efficient. On the other hand, the use of acoustic velocity alone is feasible and makes the procedure much faster, even if wet grading resulted in very conservative estimations. The yields obtained were similar for lower grades, but to achieve higher strength classes, the dynamic modulus was preferable. For very fast and less expensive measurements, velocity could be considered an appropriate method, as an improvement over the use of unselected material.

scholarly journals Influence of the moisture content on the dynamic modulus of elasticity of concrete made with recycled aggregate

2019 ◽  
Vol 19 (2) ◽  
pp. 79-89
Author(s):  
Claudio de Souza Kazmierczak ◽  
Joana Kirchner Benetti Boaro ◽  
Monique Palavro Lunardi ◽  
Marlova Piva Kulakowski ◽  
Mauricio Mancio
Keyword(s):  
Moisture Content ◽  
Modulus Of Elasticity ◽  
Dynamic Modulus ◽  
Coarse Aggregate ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Coarse Aggregates ◽  
Codes Of Practice ◽  
Dynamic Modulus Of Elasticity

Abstract The elastic behavior of the concrete is estimated from its strength or determined by static or dynamic tests. However, because the codes of practice do not standardize the internal moisture content of the concrete and disregard the use of recycled aggregates when proposing equations for the estimation of the modulus of elasticity, discrepancies between the values measured and estimated are frequent. The influence of the moisture content of concrete containing basaltic coarse aggregates and coarse recycled concrete aggregate in the dynamic modulus of elasticity is discussed in this paper. A basalt coarse aggregate and two recycled coarse aggregates where used. For each type of coarse aggregate, concrete with compression strength between 25 MPa and 55 MPa were produced. The dynamic modulus of elasticity of the saturated samples were determined and range from 26 GPa to 46 GPa. There is a significant difference in the value of the dynamic modulus of elasticity for dry concrete versus saturated concrete, also influenced by the type of aggregate. Estimations of the modulus of elasticity from the compressive strength equations proposed by the codes of practice must be improved considering its characteristics.

The Adjusted Dynamic Modulus of Elasticity Above the Fiber Saturation Point in Taiwania Plantation Wood by Ultrasonic-Wave Measurement

Holzforschung ◽  
2003 ◽  
Vol 57 (5) ◽  
pp. 547-552 ◽  
Author(s):  
S.-Y. S.-Y.Wang ◽  
C.-J. Lin ◽  
C.-M. Chiu
Keyword(s):  
Moisture Content ◽  
Bulk Density ◽  
Ultrasonic Wave ◽  
Ultrasonic Velocity ◽  
Modulus Of Elasticity ◽  
Dynamic Modulus ◽  
Fiber Saturation Point ◽  
Saturation Point ◽  
Fiber Saturation ◽  
Dynamic Modulus Of Elasticity

Summary In this study, the effects of moisture content and bulk density on the ultrasonic velocity of Taiwania (Taiwania cryptomerioides Hay.) plantation wood in the longitudinal and radial directions are investigated. The dynamic modulus of elasticity is adjusted above the fiber saturation point by a simple method. It was observed that ultrasonic velocity tended to increase with a decrease in moisture content, and the effect of moisture content on the ultrasonic speed below the fiber saturation point was stronger than that above. Moreover, for this species ultrasonic speed in the longitudinal direction decreased with increasing bulk density, while that in the radial direction increased. The correlations between ultrasonic velocity, moisture and bulk density could be represented by a polynomial regression model. The K value for ultrasonic wave was affected by density. The adjusted dynamic modulus of elasticity remained fairly constant above the fiber saturation point using this simple method. Therefore, the results obtained by the ultrasonic-wave technique should be adjusted before estimating some physical properties of standing trees.

scholarly journals Relationships and estimates of longitudinal growth stress in Eucalyptus dunnii at different ages

2008 ◽  
Vol 32 (4) ◽  
pp. 723-729 ◽  
Author(s):  
Paulo Fernando Trugilho ◽  
José Tarcísio da Silva Oliveira
Keyword(s):  
Modulus Of Elasticity ◽  
Dynamic Modulus ◽  
Basic Density ◽  
Longitudinal Direction ◽  
Growth Stress ◽  
Longitudinal Growth ◽  
Growth Stresses ◽  
Dynamic Modulus Of Elasticity ◽  
Eucalyptus Dunnii ◽  
Standing Trees

The objective of this study was to obtain estimates of longitudinal growth stresses in standing trees of the Eucalyptus dunnii Maiden at eight, thirteen, fifteen and nineteen years of age and to determine their relationships with wood characteristics. The longitudinal growth stresses were indirectly measured by the "CIRAD-Forêt" method and estimated from both the dynamic modulus of elasticity and the modulus of elasticity in tension parallel to the grain. The longitudinal residual strain (LRS) and the estimates of the longitudinal growth stresses tended to increase with the age of the material. The LRS correlated positively and significantly with all the growth stresses estimates. The largestes magnitudes were at 13, 15 and 19 years of age. The basic density presented high, positive and significant correlations with the dynamic modulus of elasticity, estimated in the longitudinal direction, for wood saturated and at 12% moisture content, for all the ages assessed. All the growth stresses estimates presented high, positive and significant correlations between themselves.

scholarly journals Prediction of Maritime Pine Boards Modulus of Elasticity by Means of Sonic Testing on Green Timber

2021 ◽  
Vol 11 (4) ◽  
pp. 1748
Author(s):  
Giovanna Concu
Keyword(s):  
Modulus Of Elasticity ◽  
Structural Timber ◽  
Maritime Pine ◽  
Manufacturing Costs ◽  
Sonic Waves ◽  
Wet Condition ◽  
Structural Grade ◽  
The Relationship ◽  
Grade Yield

Timber buildings are experiencing a rapid diffusion due to their good performance and their sustainability; however, some steps of structural timber production process, such as drying, are energy-intensive and environmentally impactful, and many wood species are also affected by low yield. Therefore, it would be important to determine the quality of the green material, that is, in wet condition, before undergoing the most impactful and expensive production steps. This paper describes a research aimed at quantifying the variation of the dynamic modulus of elasticity MoEdyn, which is commonly used for structural timber mechanical grading, from wet to dry condition in Sardinian maritime pine boards to be used for the production of laminated timber, and to examine the relationship between wet and dry MoEdyn. The MoEdyn was determined from measurements of the velocity of sonic waves propagating through the boards. The results show that the dry MoEdyn can be estimated starting from boards sonic testing in the wet condition, so providing a basis for implementing Sardinian maritime pine pre-grading in order to obtain the reduction of manufacturing costs, the abatement of environmental impact, and the increase of structural grade yield.

scholarly journals Diagnosis and Assessment of Deep Pile Cap Foundation of a Tall Building Affected by Internal Expansion Reactions

Buildings ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 104
Author(s):  
Fernando A. N. Silva ◽  
João M. P. Q. Delgado ◽  
António C. Azevedo ◽  
Tahlaiti Mahfoud ◽  
Abdelhafid Khelidj ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Reinforced Concrete ◽  
Modulus Of Elasticity ◽  
Dynamic Modulus ◽  
Structural Integrity ◽  
Gas Permeability ◽  
Ettringite Formation ◽  
Dynamic Modulus Of Elasticity ◽  
Pile Cap ◽  
Deterioration Process

Early deterioration of reinforced concrete foundations has been often reported in recent years. This process is usually characterized by an extensive mapping cracking process on concrete surfaces that results from several types of Internal Swelling Reaction (ISR). In this paper, a real case study of a tall reinforced concrete building with a severe deterioration process installed in its deep foundations is discussed. Laboratory tests were performed in concrete drilled cores extracted from a deep pile cap block 19 years after the beginning of construction. Tests to assess the compressive strength, the static and the dynamic modulus of elasticity, the gas permeability, and electron microscopy scanning to find out the primary mechanism responsible for the deterioration observed during in situ inspections. Chemical alterations of materials were observed in concrete cores, mainly due to Delayed Ettringite Formation (DEF), which significantly affected the integrity and durability of the structure. Dynamic modulus of elasticity showed to be a better indicator of damage induced by ISR in concrete than compressive strength. Procedures to strengthen the deteriorated elements using prestressing proved to be an efficient strategy to recover the structural integrity of pile caps deteriorated due to expansions due to ISR.

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