Examination of Lightning-Induced Damage in Timber

The ancient Chinese architectures were constructed using timber as the main building material. Considering that the lightning strike is the primary natural cause of damage to ancient building, the lightning strike damage mechanism of ancient building timber and the related influencing factors are investigated using the representative timber materials from the ancient building. The burning of timber was mainly caused by the heat of lightning arc. The splitting and damage pit of timber were mainly caused by the mechanical force generated by the temperature rise of the injected by lightning current and air shock wave effects of the lightning. These ways all played in different roles under different conditions. The higher the water content of timber was, the easier it was to crack, and the greater the damage depth and the larger the damage area were. It was easy to burn for the dry timber or the loose timber with low density, but it was difficult for the thick timber. When the wood was too thin, the lightning air shock wave could cause damage. This research may provide reference for protection of ancient timber architecture from possible damage caused by lightning.

Pattern recognition of wood structure design parameters under external interference based on artificial neural network with BIM environment

Under the influence of novel corona virus pneumonia, the staff are controlled. Therefore, it is a difficult problem to measure the parameters of wood structure building on site. The measurement error of traditional wood structure parameters in complex environment is large, so an efficient and accurate measurement and recognition method is needed. In this paper, a method combining random decrement method and ITD method is proposed to measure the frequency, damping ratio and other structural dynamic parameters of ancient building timber structure under crowd random load excitation. In this paper, the frequency and damping ratio of the typical ancient building timber structure are predicted by using the artificial neural network model trained by the known data. The experimental results show that the population density has a great influence on the measurement of the dynamic parameters of the wooden structure of ancient buildings. Using this method, combined with the long-term monitoring data of temperature and humidity, the influence of various environmental factors on the dynamic characteristics of the structure can be analyzed. This provides data support for structural damage identification and health monitoring.

Comparative design of the superstructure of timber bridges, using norm np 005 - 2003 and provisions of european standards

The norms and standards for design of timber bridges, as well as other structures built from this material, were obsolete, design standards that were used dated from 1978 to 1980. The introduction of European Standards has created a new legislative framework in the field of designing and building timber bridges. Currently the design of such constructions use Norm NP 005-2003 and SR EN 1995-1-1: 2004 Eurocode 5: Design of timber structures. Part 1-1: General. Common rules and rules for buildings, SR EN 1995-2: 2005 Eurocode 5: Design of timber structures. Part 2: Bridges, along with their national annexes. The aim of this paper is to analyze the design of the beams for timber bridges in parallel, using on one hand Norm NP 005 - 2003, and on the other hand provisions of European standards. The design requirements for both norms as well as the results of a case study for a structural element of a timber bridge will be presented.

The Penetration Test to Evaluate Wood Decay after 20 Years Timber Structure Assessment Experience

The Wood Penetration Test described in the present paper was set up almost 20 years ago to evaluate the timber vaulted roof decay of Palazzo della Loggia in Brescia (Italy). The test can be regarded as an extension to timber structures of the dynamic soil penetration test, as it is based on the insertion into timber structural members of a steel graduated rod, which advances by means of repeated constant energy blows transmitted by a rebound hammer. The test makes possible to distinguish between different degrees of decay as a function of the number of blows necessary for each centimetre layer penetration. This technique proved to be effective and reliable for investigating the extent and depth of wood decay and thanks to the assessment campaign the possibility of restoring the ancient vault gained strength. The test was then frequently proposed and adopted by the Structural Engineering Laboratory of Brescia University and several ancient building timber structures were checked by means of this methodology. Some significative examples will be briefly described. A recent investigation has been done on the rim beams at the basis of the Palazzo della Loggia timber vault by using the penetration test and the Resistograph and the comparison of the results is also illustrated. The test is easy to perform and the output data can be interpreted very clearly by structural engineers: it is possible to determine the depth of the decayed layers and consequently the reliable dimensions of the resisting timber sections.

“Intervals of Tranquillity”: The Language of Health in Antebellum America

Hurled into the vortex of a whirlpool, Edgar Allan Poe's protagonist in “A Descent into the Maelström” hangs suspended on a wall of water. A deafening roar like that of Niagara Falls and a haunting moan like a “vast herd of buffaloes” resound as the fisherman and his brother watch pieces of society and nature float by: “Both above and below us were visible fragments of vessels, large masses of building timber and trunks of trees, with many smaller articles, such as pieces of house furniture, broken boxes, barrels and staves.” In the midst of this swirling rubble, Poe's hero survives on luck; clutching at a water cask, he hangs on the rim of the maelstrom until the cask's buoyancy lifts him from the water's depths. Punctuated by mere “intervals of tranquillity,” this chaotic landscape emanates violence and danger.

A study of wood use for fuel and building in an area of Gazankulu

The utilization of wood for fuel and building timber was studied in a 13 000 ha area of Gazankulu, near Giyani. Headloads of firewood brought in by eight of the 978 families present were monitored during six periods in a year. The two most important sources of firewood are Colophospermum mopane and Combretum apiculatum. Firewood consumption is estimated at an average of 14,9 kg per family per day. The annual demand for firewood in the whole study area is, therefore, approximately 5 300 tonnes. Living-huts and storage-huts in the process of being built were examined. The mean volumes of wood in living-huts and typical storage-huts are 1,30 m3 and1,09 m3, respectively. 89 living- and 80 storage-huts were built in a year. The demand for finished timber in the study area in that year was approximately 231 tonnes. Timber use has not yet outstripped production, but it will do so soon if alternative timber sources are not provided.