Experimental study for non-destructive mechanical evaluation of ancient chestnut timber

Abstract

The paper deals with an experimental study for in situ mechanical characterization of ancient timber members using combined Non Destructive Testing (NDT) techniques. An experimental campaign, including non-destructive and destructive tests, was developed on timber structural elements and defect-free specimens, made of old chestnut wood (Castanea sativa Mill.). The following NDT methods were employed in the research activity: hygrometric tests to estimate wood moisture content; ultrasonic investigations to determine stress wave properties; sclerometric tests to assess material hardness and superficial consistence; resistographic measurements to detect internal defects and density variations. Destructive tests in compression parallel to grain and in bending were performed to assess stiffness and strength properties, post-elastic behaviour and collapse mechanisms of the timber elements. Experimental results are discussed and statistically analyzed. Correlations between non-destructive and destructive parameters are provided, based on linear regression models, for the prediction of the wood density, strength and modulus of elasticity of the tested old chestnut timber. The analysis shows that the use of NDT techniques is a useful supplement to the traditional visual grading, allowing a reliable mechanical identification of timber members in practical applications, leading to the appraisal of the timber structures safety and integrity

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

“…The results of the bending tests regarding stiffness and strength parameters are compiled in Table 1. Usually the value of E G is lower than E L due to the contribution of the shear deformation, however some works have attained different results [5,22]. In this work, E G,beam was slightly higher than the value of E L,beam (less than 1 % on average).…”

“…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.…”

Seismic Vulnerability Assessment of Slender Masonry Structures

“…Therefore the evaluation of the mechanical properties, especially of masonry is necessary to determine the seismic vulnerability of existing constructions and to eventually design seismic retrofitting strategies. It is crucial to have experimental data collected to characterize old and existing structures [115]. Sufficient research has not been carried out on traditional construction technology and materials used in Nepalese Pagoda temples.…”

Velocity Error Correction Based Tomographic Imaging for Stress Wave Nondestructive Evaluation of Wood

“…A significant amount of research has been conducted to explore the use of resistance drilling measurements for various applications such as tree ring analysis, tree decay detection, and structural timber condition assessment (Faggiano et al 2011, Wang 2017. From the relative drilling resistance curve, the actual internal decay severity of wood can be decided.…”