Visual grading of wood elements of road bridges in operation

Abstract

The gradual withdrawal of wood as a building material from bridge construction does not mean a complete rejection of this affordable, technological, constructive and renewable natural resource. If in the structures of supports, the main load-bearing elements of span structures, wood does not withstand the competition of steel and reinforced concrete, then the transverse load-bearing elements and the construction of the bridge bed may well be wooden, especially on regional and local roads. The northeastern regions of our country have significant reserves of coniferous forests, allowing their harvesting in industrial headquarters for use, including in transport construction. Considering that current standards allow the use of wood in bridge structures, timber is used both in the construction of new and in the repair and restoration of existing bridge structures, which usually belong to the category of small or medium bridges. Currently, there are many bridges with wooden elements in operation, especially in regions with a harsh climate, which contributes to the safety of wood structures. Operation – the longest and most productive period of the life cycle of the bridge structure and maintaining it in a standard state is the main task of maintaining the facility, one of the components of which is supervision, including diagnostics and examination in order to assess the state of the bridge for the possibility of planning maintenance, prevention, repair. In this case, a significant role is given to the establishment of the actual consumer properties of materials of the operated structures, in particular, strength at various stress conditions, and for wood, any instrumental or mechanical sorting in the operated structures is practically impossible. Thus, it is possible to assess the condition of wooden elements, including indicators of wood strength, visually based on the standards in force in this area. The purpose of this study is to visually assess the wooden bearing elements of bridges with the installation of their grade, strength class and actual durability using the example of survey data for a number of bridges.