How to improve the on-site MOE assessment of old timber beams combining NDT and visual strength grading

Cavalli, Alberto; Togni, Marco

doi:10.1080/10589759.2013.764424

Cited by 27 publications

(20 citation statements)

References 9 publications

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“…4(b), (c), with determination of coefficients 0.635 and 0.597, respectively. The findings of Cavalli and Togni (2013) showed that the MOE of old beams could be predicted by using the ED, with determination of coefficients r 2 =0.56 ～ 0.82. The developed regression formula between them was significant at the 0.001 confidence level, which indicated that the dynamic modulus of elasticity can provide good prediction of the MOE and MOR of small specimens.…”

Section: Results Of Nondestructive and Static Mechanical Testsmentioning

confidence: 99%

Nondestructive Evaluation and Reliability Analysis for Determining the Mechanical Properties of Old Wood of Ancient Timber Structure

Chen¹,

Guo²

2017

BioResources

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The objective of this study was to evaluate the mechanical properties of ancient wood of Abies fabri (Mast.) Craib based on the nondestructive tests and reliability analysis. Nondestructive tests including resistograph and stress wave test, and destructive tests were conducted on the wood specimens. Results indicated that there were significant linear correlations between the resistance amplitude (F) and green density (ρ), the dynamic modulus of elasticity (ED) and static modulus of elasticity (MOE), modulus of rupture (MOR), and ultimate compressive strength (UCS) of wood specimens. The cumulative distribution of the predicted MOR and UCS based on the nondestructive tests could be well fitted by the normal distribution according to the χ 2 test. Moreover, a reliability analysis program based on the first-order second-moment method was developed. Reliability analysis results showed that the reliability index increased nonlinearly with the increase of the live-to-dead load ratio, and decreased nonlinearly with the increase of the design values for all the simulation load cases. According to the minimum reliability index requirements of the Chinese national standard, it is suggested that the design value of MOR and UCS be 14.0 and 10.7 MPa, respectively.

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Section: Results Of Nondestructive and Static Mechanical Testsmentioning

confidence: 99%

Nondestructive Evaluation and Reliability Analysis for Determining the Mechanical Properties of Old Wood of Ancient Timber Structure

Chen¹,

Guo²

2017

BioResources

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“…The error of prediction can be partially dealt if the NDT or SDT method is applied taking into consideration important characteristics of the member (namely wood species, growth ring pattern and spatial variation inside the member) and if a sufficient number of readings are collected. The determination of penetration resistance along the length of the beam can provide more reliable data by incorporating possible density's lengthwise variation pattern [32]. As this method only considers the surface layers of the timber element, it does not take into account the cross-section variation that can be much larger that the longitudinal variation.…”

Section: Densitymentioning

confidence: 99%

“…Modulus of elasticity in bending is often determined considering information obtained through NDT made onsite, for example using flexural and longitudinal vibrational tests, stress wave transmission time, penetration depth, and its correlation to laboratory tests [32]. However, the information obtained should always be complemented with visual grading of the timber element, since as mentioned in [38] for ancient timber elements, the knot incidence (knot diameter to depth/width ratio) and slope of grain, are important influencing parameters that may lead to significant MOE reduction.…”

Section: Modulus Of Elasticity In Bendingmentioning

confidence: 99%

Onsite assessment of structural timber members by means of hierarchical models and probabilistic methods

Sousa

Machado

Branco

et al. 2015

Construction and Building Materials

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a b s t r a c tOne of the main motivations for hierarchical modeling is to understand how properties, composition and structure at lower scale levels may influence and be used to predict the material properties at macroscopic and structural engineering scales. Structural timber is, in most cases, characterized by three parameters usually designated as reference properties: density, bending modulus of elasticity and bending strength.The present paper addresses a review on different possibilities for obtaining reliable data about the mechanical behavior of timber elements by collecting information at different levels and by organizing that information into a hierarchy of sequential levels (from lowest to highest). The applicability and limitations of statistic and probabilistic methods on the prediction and inference of timber's reference material properties are discussed and exemplified.

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“…Correlations among these properties and with other mechanical properties are commonly found in literature [1]. In addition, several works address the correlation of these properties with non-destructive tests (NDT) [2][3][4][5][6][7][8]. As mentioned by [9], many works demonstrate the adequacy of NDT, such as acousto-ultrasonic tests, visual grading, knot diameter ratios and other indirect methods like machine grading to estimate bending MOE and density.…”

Section: Introductionmentioning

confidence: 99%

“…As mentioned by [9], many works demonstrate the adequacy of NDT, such as acousto-ultrasonic tests, visual grading, knot diameter ratios and other indirect methods like machine grading to estimate bending MOE and density. In Cavalli and Togni [2], old timber members were visually graded and tested with different nondestructive techniques for the density and MOE estimation. However, the prediction of bending strength, which is influenced by the visual grading parameters of timber, is less well defined.…”

Section: Introductionmentioning

confidence: 99%

Inference on stiffness and strength of existing chestnut timber elements using Hierarchical Bayesian Probability Networks

et al. 2015

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The assessment of the mechanical properties of existing timber elements could benefit from the use of probabilistic information gathered at different scales. In this work, Bayesian Probabilistic Networks are used to hierarchically model the results of a multiscale experimental campaign, using different sources of information (visual and mechanical grading) and different sample size scales to infer on the strength and modulus of elasticity in bending of structural timber elements. Bayesian networks are proposed for different properties and calibrated using a large set of experimental tests carried out on old chestnut (Castanea sativa Mill.) timber elements, recovered from an early 20th century building. The obtained results show the significant impact of visual grading and stiffness evaluation at different scales on the prediction of timber members' properties. These results are used in the reliability analysis of a simple timber structure, clearly showing the advantages of a systematic approach that involves the combination of different sources of information on the safety assessment of existing timber structures.

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How to improve the on-site MOE assessment of old timber beams combining NDT and visual strength grading

Cited by 27 publications

References 9 publications

Nondestructive Evaluation and Reliability Analysis for Determining the Mechanical Properties of Old Wood of Ancient Timber Structure

Nondestructive Evaluation and Reliability Analysis for Determining the Mechanical Properties of Old Wood of Ancient Timber Structure

Onsite assessment of structural timber members by means of hierarchical models and probabilistic methods

Inference on stiffness and strength of existing chestnut timber elements using Hierarchical Bayesian Probability Networks

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