Field fire tests of an orthotropic plate made of 6082T6 aluminium alloy showed a high fire resistance of this structure.
The tests, which were carried out at the site of the National Research Moscow State University of Civil Engineering (MGSU) in Mytishchi, were aimed at obtaining experimental data on the level of fire resistance and actual integrity loss indicators, as well as the bearing and thermal insulation capacity of aluminium bridge structures in the event of a fire. During testing at temperatures up to 500°C, the plate deflection was 65 mm, and the fire resistance limit was 57 minutes.
The field tests are part of an extensive research and development programme (R&D) carried out by specialists from MGSU, MADI and the Aluminium Association with the aim of further expanding the application of Code of Rules 443.1325800.2019 'Bridges with Aluminium Alloy Structures. Design Rules' to road bridges. Currently, code 443 applies only to pedestrian bridge structures made of aluminium alloys. The data obtained in the course of field and laboratory tests of orthotropic plates will be included in the new edition of Code 443 with respect to road bridges made of aluminium alloys. The document will be submitted to the Ministry of Construction of Russia for approval.
Besides, the results of bridge structure testing – static and fatigue tests of orthotropic plates were carried out earlier – will be taken into account in the special technical conditions when designing the first road aluminium bridge in Russia for the Nizhny Novgorod Region. An agreement was reached with the bridge designers to work out the terms of reference in the first quarter of 2021. The aluminium bridge is expected to be built and launched in the next year too.
INFORMATION
Code of Rules 443.1325800.2019 'Bridges with Aluminium Alloy Structures. Design Rules' was approved by the Ministry of Construction of Russia in April 2019. Specialists of MGSU, UC RUSAL and the Aluminium Association took part in preparation of the document. Technical Committee for Standardisation 'Construction' TK-465 provided significant support to this work. Previously, designing and constructing aluminium alloy bridges was significantly complicated by the need to develop special technical conditions (STU) for each designed bridge individually, which increased the cost and design time.
Orthotropic plate is a hollow slab for absorbing loads from the roadway with longitudinal vertical and inclined ribs between the upper and lower horizontal panels. It is called orthotropic because its rigidity in the longitudinal and transverse directions is different. Aluminium plates consist of a small number (7-10) of extruded hollow elements, connected by the advanced friction stir welding method. This method provides a higher quality connection than traditional argon-arc welding.