Probabilistic procedure for design of untreated timber poles in-ground under attack of decay fungi

Wang, Chi-Hsiang; Leicester, R H; Nguyen, Minh

doi:10.1016/j.ress.2006.12.007

Cited by 58 publications

(35 citation statements)

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“…The decay was defined by an idealized model with two parameters (Leicester, 2001): the time of incubation or the time between the installation of the timber element and the point that noticeable decay commences, t lag (year), and an annual decay rate, r (mm/year) (Figure 8). According to Wang et al (2006), the parameters may be given by:…”

Section: 5mentioning

confidence: 99%

“…Considering a probabilistic analysis, the t lag parameter is to be defined as a deterministic variable, while the r parameter should be defined by a lognormal distribution with a coefficient of variation between 0.5 and 1 according to the timber durability class (Wang et al, 2006). With respect to the geometrical survey, the initial cross sections without deterioration were used and the safety level of the timber trusses was first estimated.…”

Section: 5mentioning

confidence: 99%

“…A detailed discussion on the probabilistic modelling of timber structures can be found in and . Decay may also be modelled using probabilistic methods (Leicester, 2001;Wang et al, 2006), as predictions on decay evolution and its consequences on structural safety and maintenance planning may be considered using time evolution deterioration curves. The concept of life-cycle performance evaluation of deteriorating structures has been studied by several authors (Thoft-Christensen, 1998;Nowak et al, 1998;Frangopol et al, 2001;Kong and Frangopol, 2002;Neves and Frangopol, 2005) for concrete and steel structures, and it is possible to adapt the same conceptual framework for the life-cycle design of timber structures, provided that the uncertainties in the input variables are quantified (Frangopol et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

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In situ measured cross section geometry of old timber structures and its influence on structural safety

et al. 2012

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Old timber structures may show significant variation in the cross section geometry along the same element, as a result of both construction methods and deterioration. As consequence, the definition of the geometric parameters in situ may be both time consuming and costly. This work presents the results of inspections carried out in different timber structures. Based on the obtained results, different simplified geometric models are proposed in order to efficiently model the geometry variations found. Probabilistic modelling techniques are also used to define safety parameters of existing timber structures, when subjected to dead and live loads, namely self-weight and wind actions. The parameters of the models have been defined as probabilistic variables, and safety of a selected case study was assessed using the Monte Carlo simulation technique. Assuming a target reliability index, a model was defined for both the residual cross section and the time dependent deterioration evolution. As a consequence, it was possible to compute probabilities of failure and reliability indices, as well as, time evolution deterioration curves for this structure. The results obtained provide a proposal for definition of the cross section geometric parameters of existing timber structures with different levels of decay, using a simplified probabilistic geometry model and considering a remaining capacity factor for the decayed areas. This model can be used for assessing the safety of the structure at present and for predicting future performance.

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Section: 5mentioning

confidence: 99%

Section: 5mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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In situ measured cross section geometry of old timber structures and its influence on structural safety

et al. 2012

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“…(Nabuurs and Sikkema, 2001). The service life determination of wooden components is a critical research constraint that needs a thorough investigation of material properties before it is possible to make predictions (Brischke and Rapp, 2008;Gupta et al, 2009Gupta et al, , 2010Haagenrud, 1996;Hovde et al, 2008;ISO 2000ISO , 2008Jernberg et al, 2004;Kalamees, 2002;Sarja et al, 1999;Sjö strom and Brandt, 1991;Wang et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Studies of wooden cladding materials degradation by spectroscopy

Gupta¹,

Jelle

Jostein

et al. 2011

Proceedings of the Institution of Civil Engineers - Constructio

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Claddings or façades are the outer part of building envelopes. In this study, wooden claddings are exposed to natural and accelerated weathering. The natural climate exposure was performed at a field test site located in Trondheim,Norway. Accelerated climate exposure was performed in the laboratory in an Atlas SC600 MHG solar simulator.Attenuated total reflectance -Fourier transform infrared (ATR-FTIR) spectroscopy was used to characterise surfaces.The objective was to assess degradation by use of FTIR and thereby see how this may be applied to evaluate the service life of wood. Four types of wooden materials were studied; three untreated and one treated with chromated copper arsenate. Surface concentrated cellulose and lignin are the primary wood components used to determine the quality and durability of wood during ageing. It was found that treatment with preservative chemicals and surface roughness has definitive impacts on cladding surfaces and change to the chemical properties of the materials during ageing. The acceleration factor deduced from the Arrhenius equation shows that an increase in temperature lowers the service life of cellulose at a higher rate than the other wood components.

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“…These tests can include artificial exposure to wood decay fungi and / or controlled or accelerated environmental conditions, or can be conducted in real time without artificial or controlled accelerants and conditions. These types of above-ground tests are often conducted at multiple geographic locations simultaneously, with correlations between results based on climatic data for each region (Wang et al, 2008). However, the correlation between deterioration and climatic data is "often weak" (Daniotti and Cecconi, 2010).…”

Section: Traditional Basis For Determining Rate Of Decay In Woodmentioning

confidence: 99%

Deterioration of Wood Structures—Basic Forensic Considerations

Anthony¹

2012

Forensic Engineering 2012

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The rate of decay in buildings, particularly of wood components and woodbased materials, is an issue that has become an area of focus in the construction and engineering industries, where estimating building performance and service life is becoming standard practice during construction litigation. While this may be a worthy goal, the technical data to allow for determining a specific time when wood decay began and to make statements about the rate of decay to a reasonable degree of scientific certainty generally do not yet exist. There are two primary means by which the rate of wood decay has been investigated: one is through experimental research such as in-ground stake tests, soil block tests, and wood exposure tests on various wood components and wood-based products. The second approach is through the development of service life prediction models. These models are based on data from experimental research, climate indicies, and other factors deemed to be significant in decay processes. The factors are used to make assumptions about the propensity of a certain wood component, configuration, species, or wood-based product to deteriorate over time. The focus of this paper is to present basic considerations when attempting to establish the rate of decay of wood and wood products used in construction.

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Probabilistic procedure for design of untreated timber poles in-ground under attack of decay fungi

Cited by 58 publications

References 1 publication

In situ measured cross section geometry of old timber structures and its influence on structural safety

In situ measured cross section geometry of old timber structures and its influence on structural safety

Studies of wooden cladding materials degradation by spectroscopy

Deterioration of Wood Structures—Basic Forensic Considerations

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