Some background of monitoring and NDT also useful for timber structures

Kurz, Jochen H.; Boller, Christian

doi:10.1007/s13349-015-0105-z

Cited by 14 publications

(12 citation statements)

References 43 publications

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“…The inspection of timber structures using NDT is another relevant approach when working with heritage timber structures. NDTs are fundamental as tools that allow the acquisition of important information, without causing damages [28] or only inducing imperceptible markings. The application of NDT has gradually been further expanded over the past three decades [29].…”

Section: Background: Traditional Carpentry and Non-destructive Testin...mentioning

confidence: 99%

On-Site Risk Assessment Methodology of Historic Timber Structures: The Case Study of Santa Cruz Church

et al. 2022

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The conservation and repair of historic structures require significant resources. Therefore, it is important to conduct a complete assessment of the object. Specifically, historical timber frame structures are very common in the Spanish and Andalusian geographic area. This research proposes and develops a simplified approach to facilitate decision making when faced with this complex work. By the application of long-established non-destructive tests, such as organoleptic and measuring inspection, resistography, and electric moisture content test, combined with visual classification parameters, these data were used as boundary conditions into a simplified structural calculation method. This process, which is simpler than other calculation systems, allows compiling important information about the safety level of the structure and its critical points. Finally, it allows for a better approach to repair work while rationalizing resources. This method was applied to a historical structure, during an 18th century church repair project. The assessment methodology provided important information about the conservation state of the timber frame and its structural suitability.

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Section: Background: Traditional Carpentry and Non-destructive Testin...mentioning

confidence: 99%

On-Site Risk Assessment Methodology of Historic Timber Structures: The Case Study of Santa Cruz Church

et al. 2022

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“…In 2015, it was reported that no state of the art in structural monitoring of timber construction exists (Kurz 2015), which could improve the durability of the construction and optimize maintenance. The main methods in non-destructive testing for assessment of timber structures have been summarized (Kasal and Tannert 2010;Kurz and Boller 2015), but are rarely used for long-term monitoring of structures. Several assessment techniques are in use to continuously prove public construction sites like bridges, but these assessments require ongoing investment.…”

Section: Introductionmentioning

confidence: 99%

Improving the usability of piezoresistive bond lines in wood by using impedance measurements

2021

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Various studies on wood adhesives filled with conductive fillers for future application to structural monitoring showed a piezoresistive (resistance change with strain) response of the adhesive bond lines that is measurable under direct current. The results also showed a relatively high signal noise with low sensitivity. Using impedance spectroscopy as a measurement technique, the improvements in frequency-dependent piezoresistivity over DC (Direct Current) resistography of multifunctional bonded wood were studied. Beech specimens were bonded by one-component polyurethane prepolymer (1C-PUR) filled with carbon black and tested under shear load. The quality of the piezoresistive properties was described by calculating the signal-to-noise ratio (SNR) of the measured signal. A setup-specific frequency band with optimized SNR between 100 kHz and 1 MHz could be derived from the measurements. Several frequencies showed a signal with higher quality resulting in a higher SNR. Regardless of the variations in impedance spectra for all specimens, this frequency band provided several frequencies with improved signal quality. These frequencies give a more reliable signal with lower noise compared to the signal from DC resistography.

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“…In the last years, the currently available methods for assessing and monitoring timber structures non-or less destructively have been reviewed and it was shown that several sensors are usable and reliable for monitoring purposes (Koch et al 2016;Kurz 2015;Kurz and Boller 2015;Tannert et al 2010;Tannert and Müller 2010).…”

Section: Introductionmentioning

confidence: 99%

Piezoresistive bond lines for timber construction monitoring—experimental scale-up

et al. 2021

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Several laboratory studies and experiments have demonstrated the usability of polymer films filled with electrically conductive filler as piezoresistive material. Applied to adhesives, the glue lines of wood products can achieve multifunctional—thus bonding and piezoresistive/strain sensing—properties. Based on critical load areas in timber constructions, upscaled test setups for simplified load situations were designed, especially with regard to a stress-free electrical contact. In a second step, another upscaling was done to small glulam beams. Based on an experimental test sequence, the piezoresistive reactions as well as the behaviour until failure were analysed. The results show in all cases that a piezoresistive reaction of the multifunctionally bonded specimens was measurable, giving a difference in the extent of relative change. Additionally, measured phenomena like inverse piezoresistive reactions, electrical resistance drift and the absence of a piezoresistive reaction were discussed, based on additional strain analysis by digital image correlation. A model of macroscopic and microscopic strains influencing the piezoresistive reaction of the electrically conductive bond line in wood was used to explain all experimental results. Finally, a first scale-up of piezoresistive bond lines from laboratory samples to glulam beams was possible and successful.

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Some background of monitoring and NDT also useful for timber structures

Cited by 14 publications

References 43 publications

On-Site Risk Assessment Methodology of Historic Timber Structures: The Case Study of Santa Cruz Church

On-Site Risk Assessment Methodology of Historic Timber Structures: The Case Study of Santa Cruz Church

Improving the usability of piezoresistive bond lines in wood by using impedance measurements

Piezoresistive bond lines for timber construction monitoring—experimental scale-up

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