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Statistical analysis of wooden cladding moisture response to climate parameters
Published in Paul Fazio, Hua Ge, Jiwu Rao, Guylaine Desmarais, Research in Building Physics and Building Engineering, 2020
The statistical software programme used is MINITAB®. The analysis includes hourly values and daily mean (24-hour) values. The daily mean values are averaged for most parameters, but totalled for precipitation and WDR. The potential for decay in wood increases with growing moisture content and increasing air temperatures. The measured MC may be used directly as a criterion value for decay potential. Another criterion value is deduced from Mukhopadhyaya et al. (2005) as follows: MR=MC∗T∣T≥5MR=MC∣T<5 where T is the measured cladding temperature.
Case studies on spatial timber constructions in modern architecture and public art
Published in Paulo J.S. Cruz, Structures and Architecture: Bridging the Gap and Crossing Borders, 2019
In the course of time however, the limitations of using wood in construction became apparent, due to a number of distinct drawbacks, such as unstable material quality, inflammability, tendency to decay and so on. In the early of the 20th century, with the development of wood science and technology, new wooden engineering materials with high mechanical properties, such as OSB board, veneer laminated wood, plywood, etc., accompanied by prefabrication technology, were invented, making it possible to overcome these problems and develop a new type of modern wood structure. Modern frame wood construction systems possess clear logic, elegant form and constructional details. We can ascertain a clear continuation and relationship between the traditional wood structure and the modern frame wood structure.
Doors and windows
Published in James Douglas, Bill Ransom, Understanding Building Failures, 2013
The presence of decay in the woodwork of doors and windows is readily detected. The timber surface is often dished, through the falling away of the soft and friable underlying timber. Paint surfaces are generally cracked and peeling away from the underlying wet timber. Putty is usually loose, having shrunk away from the timber, and pieces are cracked or missing. Replacement of putty is comparatively straightforward but, whether or not it is feasible to cut out any decayed timber and renew it with preserved timber, clearly will depend upon the extent of the decay. Total replacement may be necessary. Where decay is localised, it may be possible to cut out the affected wood, to apply liberally a suitable preservative and to replace with treated wood. It will be necessary, generally, to remove and replace the putty and paint, and to fill open joints with a water-insoluble filler. The British Woodworking Federation has its own performance standard for wood windows and included in the scope of this standard is the requirement for preservative treatment where necessary. In practice this means that all softwood windows manufactured by its members are impregnated with preservatives.
Structural health assessment techniques for in-service timber poles
Published in Structure and Infrastructure Engineering, 2023
Sahan Bandara, Pathmanathan Rajeev, Emad Gad
Timber is a bio-degradable material that deteriorates with time mainly due to weathering, fungal attack and termite attack. Furthermore, fires can have a negative impact on the mechanical properties of wood and are therefore another source of degradation (Mudiyanselage, Rajeev, Gad, Sriskantharajah, & Flatley, 2020). Weathering is the degradation of the surface of wood due to extreme environmental conditions such as the repetition of wet and dry conditions in wood surface, exposure to high and low temperatures and direct exposure to sun light. Wood decay is caused by the fungal attack and the rate of decay depends on the natural durability of wood and the changes in local climatic conditions. Less durable timber species subjected to climatic changes loose about 25% of the residual strength after 50 years of installation (Wang, Leicester, & Nguyen, 2008). The decay occurs as a result of the interaction among organisms that utilise timber as a source of food for their growth. The fungal attack takes place only when conditions favourable for fungal growth are satisfied (e.g. availability of favourable moisture content, oxygen levels, temperature range, and the presence of nutrients).
Oxidized polyethylene as a new alternative coupling agent for the fiberboards made from UF resin
Published in The Journal of Adhesion, 2020
Hamed Younesi-Kordkheili, Antonio Pizzi
Bagasse is the residue after sugarcane stalks are crushed for sap extraction. In the past, a typical practice to dispose of it was to either burn it or to either allow it to decay or to use it for landfilling, resulting in significant environmental problems. Compared to other lignocellolosic materials, bagasse has excellent properties including low cost, low density and abundant availability. For these reasons, today’s bagasse is used as a raw material for production of chemicals, fuels and others. One of the most important applications of bagasse fiber is in fiberboard production, especially in countries where forest resources are lacking. Previous studies have indicated the properties of the panels made from bagasse fiber are comparable with those made from wood fiber [1]. However, among the agriculture residue such as rice husk and wheat straw, sugarcane bagasse presents the highest proportion of silica content. The presence of silicates together with hydrophobic extractives in the external surface of bagasse fiber reduces its wettability by water-based adhesives such as for urea-formaldehyde (UF) resins. Generally, despite the several advantages of UF resins, the panels bonded with them present formaldehyde emission and low moisture resistance. These defects together with the lower bonding capability of bagasse fiber by UF resins has hindered the development of fiberboards based on bagasse. Thus, this study aims to find a new way to overcome the problems inherent to bagasse fiber-UF resin panels.
Research on the Characteristics of Timber Frames of Tingtang in Residences of Ming and Qing Dynasties in Shanghai
Published in International Journal of Architectural Heritage, 2020
Since modern times, Shanghai has been portrayed as an international metropolis. While at the same time, Shanghai also possesses a number of exquisite Ming and Qing residential buildings with distinct regional features. It is of great significance to study them. However, the reality is that only a few of them have been established as heritage conservation units, protected by law, managed and repaired by specialized agencies. More buildings become old in daily use with little attention. Because of some defects in wood (such as flammable, tending to be decayed and wormy), the main material of the structure, improper use or lack of maintenance is detrimental to the safety of the building. Furthermore, some of the buildings are even damaged during the process of accelerated urban construction. The urgent situation makes the investigation to the surviving traditional architectures of irreplaceable significance. This research is based on the on-site investigation of more than 50 typical Ming-Qing tingtangs.