An Investigation of the Duration of Load of Structural Timber and the Clear Wood

Wu, Qiongyao; Huo, Liangliang; Zhu, Eryu; Niu, Shuang; Wang, Huajie

doi:10.3390/f12091148

Cited by 6 publications

(10 citation statements)

References 6 publications

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“…The predictions by the above models for the DOL factors, i.e., the stress ratios ( S ) of BS in different service durations are listed in Table 3 , together with those of OSB [ 14 ], the Madison curve [ 10 ], glulam parallel to the grain [ 15 ], and glulam perpendicular to the grain [ 7 ]. The DOL factors of BS perpendicular to the grain predicted by the three models were all greater than 0.4, confirming the rationalization value of the threshold stress ratio ( ŋ ).…”

Section: Resultsmentioning

confidence: 99%

The Long-Term Mechanical Properties of BS Perpendicular to the Grain

Luo

Ren

et al. 2022

Polymers

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As a modern bamboo composite with good mechanical properties, bamboo scrimber (BS) has achieved prominence in the sustainable architecture field. When used as a structural material, it is inevitably under continual tension perpendicular to the grain, therefore its mechanical response under long-term loading is significant for structural design. In this study, tensile tests were conducted on BS under short-term and long-term loads perpendicular to the grain. The duration of load (DOL) effect on BS perpendicular to grain and its creep effect were analyzed. Compared with BS parallel to the grain, the DOL effect on BS perpendicular to the grain was less severe, and the capacity for creep resistance was weaker. The threshold stress ratio and relative creep strain of BS perpendicular to the grain were 0.40 and 0.87, respectively. It was found that the DOL models and the viscoelastic model accurately predicted the DOL factor and creep strain. This study provides a scientific reference for the safe lifetime service of BS in practical engineering.

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Section: Resultsmentioning

confidence: 99%

The Long-Term Mechanical Properties of BS Perpendicular to the Grain

Luo

Ren

et al. 2022

Polymers

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“…The DOL effect is generally represented as a ratio of long-term strength to shortterm strength [52]. Material strength is usually determined through destructive tests, but because damage to the material can only occur once, the same specimen cannot be tested in both short-term strength and long-term strength tests [25]. In this regard, it is impossible to accurately assess the DOL effect of the same specimen by means of experimentation.…”

Section: Dol Effect With Percentile Matching Methodsmentioning

confidence: 99%

“…A special lever-loading device is usually used to deliver the load for long-term tests [21,24,25], as shown in Figure 1a. The aim of long-term tests is to obtain the time to failure T f of the specimen under constant loads at a given level.…”

Section: Long-term Testmentioning

confidence: 99%

“…In 1741, Buffon first discovered the DOL phenomenon in oak beams that had been under long-term bending loads, which led to the widespread recognition of the DOL effect as an important performance of structural timber [8,9]. A large number of DOL tests have been conducted on different species of structural timber to analyze the patterns of constants loads, including tension perpendicular to grain loads [10][11][12][13][14][15][16][17][18], bending loads [19][20][21][22][23][24][25], and shear loads [26][27][28] as well as the different factors that influence the DOL effect in structural timber, such as stress levels (SL) [15][16][17]27], climatic factors (moisture content and relative humidity) [13,21,22,24,29], and the geometric dimensions of the test specimen (small clear specimens, dimensional lumber, and structural lumber) [19,23,25,30,31]. The DOL effect and its adjustment to the design value of structural timber strength were studied based on the empirical fitting of experimental data, cumulative damage mechanics, or linear elastic fracture mechanics theory.…”

Section: Introductionmentioning

confidence: 99%

“…Hoffmeyer et al [24] published the final results of their 13-year study on DOL effects, which focused on the effect of moisture content on the DOL effect in structural timber subjected to constant bending loads. Zhu et al [25] conducted short-term and long-term bending tests using No. 2 and No.…”

Section: Introductionmentioning

confidence: 99%

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Re-Analysis of Historical Data and Model Calibration of Duration of Load Effect on Structural Timber

Zhao

Zhang

et al. 2023

Buildings

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The duration of load (DOL) effect in structure timber refers to the degradation of strength and stiffness that occurs under long-term continuous loading. This paper investigated the DOL effect in structure timber using DOL tests and DOL damage models. Based on the empirical-fitted formulae, the DOL coefficients were derived for three long-term sustained loads in bending, tension perpendicular to grain, and shear parallel to grain, and the results were compared and analyzed with the Madison equation, Gerhards model, Nielsen model, and Foschi and Yao model derivations to verify the applicability of the DOL empirical model and the three DOL damage models. The results show that based on the historical data of the DOL tests, the Madison empirical formula was found to be better applied to the derivation of DOL coefficients under the bending and tension perpendicular to grain long-term sustained loading, and the derivation of DOL coefficients under shear loading is not satisfactory. Among the three DOL damage models, the Foschi and Yao model was better than the Gerhards and Nielsen models for fitting the DOL test results under bending, tension perpendicular to grain, and shear parallel to grain. The DOL coefficients derived based on the Foschi and Yao model are more comparable to test results and resemble those derived from the Madison formula.

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A Review of the Applicability of Non-destructive Testing for the Determination of the Fire Performance of Reused Structural Timber

Uldry,

Husted,

Pope

et al. 2024

J Nondestruct Eval

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This paper presents a review of the possible methods for testing the fire performance properties of reused timber through non-destructive techniques, focusing on structural elements. Evaluating the fire performance of old wooden specimen is necessary to facilitate reuse, in the support of the transition to a circular economy. The use of non-destructive methods minimizes damages to the pieces during the evaluation process. Three angles are reviewed: (1) The properties of wood influencing fire performance, (2) the change of wood properties over time, and (3) the known non-destructive tests. Some properties of wood are known to influence the fire performance, e.g., the density. Of these, there is no evidence of irreversible changes due to the passage of time only. The many different non- and semi- destructive techniques that can be applied to wood seldom relate to these properties, but rather to mechanical properties or geometry. Additionally, accurate measurements are often difficult, while some are only done in laboratories. This review concludes that currently there is no known non-destructive method that permits to estimate the fire performance of a reused timber element compared to a new one. There is a gap of knowledge on the evolution of the fire properties of timber during the use phase of the building, and there are no established methods to test for these properties without destroying a significant portion of the element. Development of non-destructive test methodologies to assess fire properties of timber will expand the market for reused timber to include load carrying timber.

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An Investigation of the Duration of Load of Structural Timber and the Clear Wood

Cited by 6 publications

References 6 publications

The Long-Term Mechanical Properties of BS Perpendicular to the Grain

The Long-Term Mechanical Properties of BS Perpendicular to the Grain

Re-Analysis of Historical Data and Model Calibration of Duration of Load Effect on Structural Timber

A Review of the Applicability of Non-destructive Testing for the Determination of the Fire Performance of Reused Structural Timber

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