Moisture content adjustments for dynamic modulus of elasticity of wood members

2009 ◽  
Vol 44 (3) ◽  
pp. 485-495 ◽  
Author(s):  
J. David Barrett ◽  
Jung-Pyo Hong
Keyword(s):  
Moisture Content ◽  
Modulus Of Elasticity ◽  
Dynamic Modulus ◽  
Dynamic Modulus Of Elasticity

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 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 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.

scholarly journals Effects of ring characteristics on the compressive strength and dynamic modulus of elasticity of seven softwood species

Holzforschung ◽  
2007 ◽  
Vol 61 (4) ◽  
pp. 414-418 ◽  
Author(s):  
Cheng-Jung Lin ◽  
Ming-Jer Tsai ◽  
Chia-Ju Lee ◽  
Song-Yung Wang ◽  
Lang-Dong Lin
Keyword(s):  
Compressive Strength ◽  
Statistical Analysis ◽  
Modulus Of Elasticity ◽  
Dynamic Modulus ◽  
Ring Width ◽  
Ring Density ◽  
Dynamic Modulus Of Elasticity ◽  
Wave Technique ◽  
Wood Strength ◽  
Softwood Species

Abstract The effects of ring characteristics on the compressive strength and dynamic modulus of elasticity of seven softwood species in Taiwan were examined. The results revealed good correlation between compressive strength and dynamic modulus of elasticity obtained using an ultrasonic wave technique (correlation coefficient r=0.77–0.86). Overall, compressive strength increased with decreasing ring width parameters and increasing ring density parameters. Ring density was related to compressive strength, but was not the sole factor affecting the wood strength. According to our statistical analysis, compressive strength was affected by various ring characteristics. Relationships between ring characteristics and compressive strength are influenced by the anatomic direction. Results revealed that earlywood density and minimum density in a ring are equally important variables for evaluating the compressive strength of wood.

Some Dynamic Properties of Rubber

1942 ◽  
Vol 9 (3) ◽  
pp. A129-A135
Author(s):  
C. O. Harris
Keyword(s):  
Modulus Of Elasticity ◽  
Dynamic Modulus ◽  
Dynamic Properties ◽  
Internal Damping ◽  
Standard Practice ◽  
Dynamic Modulus Of Elasticity

Abstract The purpose of the investigation described in this paper was to obtain information concerning the dynamic properties of rubber bonded to metal. Two properties of rubber were measured (a) the internal damping and (b) the dynamic modulus of elasticity. Two types of specimens were tested (a) rubber cylinders bonded to steel cylinders at the ends and stressed in compression and (b) specimens of rubber bonded to steel and stressed in shear. All specimens were of the same stock, 5140-V-4, manufactured by the U. S. Rubber Company. The hardness, as measured by the durometer, varied from 32 to 40. In the process of bonding to the steel, a 1/32-in. layer of 60-durometer stock was added adjacent to each piece of steel. This represents standard practice of the U. S. Rubber Company in bonding soft stock to metal. All specimens were cured for 30 min at 279 F.

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