رفتار سازه از پانل های عرشه پل آلومینیوم

The use of lightweight bridge decks made of FRP composites or aluminium alloys is particularly effective for replacing deteriorated bridge decks. Therefore a research program has been undertaken to develop and implement an innovative aluminium bridge deck system, which would be applicable and realizable in domestic conditions. Several service load and ultimate load tests have been carried out on the prefabricated 2.10×3.20 m deck panels, in order to examine and evaluate the panel behaviour under standard truck load, and when loaded to failure. The results of the service load study indicated adequate strength and stiffness of the deck panel. Two ultimate-load tests were conducted to further investigate the failure mechanism. The study clearly demonstrates that an aluminium bridge deck panel is a feasible alternative to RC decks from the standpoint of stiffness, strength and load carrying capacity.

The most vulnerable element of a bridge is its deck. Bridge deck deterioration of older bridges is a significant problem in aging of the highway system. Therefore, RC bridge decks must be replaced every ten to fifteen years. Use of an advanced material bridge deck system is viewed as a potential long-term solution for the concrete deck deterioration problem. The recently developed redecking systems can be grouped according to the material used. The groups are: (1) conventional materials as concrete, steel and timber and (2) modern advanced materials such as engineered cement composite, glulam timber, aluminium alloys and FRP composites. The contemporary progress of metal engineering, which led to the development of new generation aluminium alloys with excellent strength and durability, had led to wider utilisation of this material in civil and transportation engineering [1]. Particularly effective is the use of aluminium alloys in bridge redecking, see Höglund [2], Matteo [3], Okura et al. [4], Soetens and Van Straalen [5]. The removal of a deteriorated heavy RC deck and the replacement with a lighter one, engineered with aluminium, make possible to avoid the strengthening of the superstructure and substructure and thus cut the total cost of modernization. Furthermore the excellent corrosion resistance of aluminium alloys brings the saving of cost, spent for maintenance during service life of a bridge, eliminating also during that time a lot of environmental issues due to painting for corrosion protection. Additionally the application of aluminium deck shortens the closing time of the bridge, needed for carrying out the rehabilitation works. It also reduces the social costs caused by traffic congestions [6]. Recognizing the potential benefits that aluminium could offer the transportation industry, the Department of Roads and Bridges at RUT has undertaken a research program to develop and implement an aluminium bridge deck system, which would be realizable and applicable in domestic conditions. The first phase of this study was to design aluminium extrusions and panels, suitable to bridge decks. On the basis of existing solutions, see Höglund [2], Matteo [3], Okura et al. [4], Soetens and Van Straalen [5], the geometry of extrusion’s cross-section has been elaborated and optimized for domestic requirements and production possibilities, and the bridge deck panel made of those extrusions has been designed. The multicriterion analysis carried out according to [7] has showed that the best solution is multi-voided deck with triangle holes. The limit state code checking for the designed aluminium panel has revealed the required capacity, stiffness and safety level, when checked according to Eurocode 9 [8]. The second phase of the study, which is partially reported here, involves the experimental evaluation of the deck panel. Several service load and ultimate load tests have been carried out on the prefabricated 2.10 × 3.20 m deck panels, in order to examine and evaluate the panel behaviour under standard truck load and when loaded to failure. Phase three of the study will focus on the structural and environmental durability of a deck panel on the basis of fatigue testing in the laboratory and corrosion testing in the bridge environment. At the same time, the durability of the wearing surface will be assessed. The last, fourth phase of the study will involve a field evaluation of the deck system, which will replace a deteriorated RC deck. The final results of these tests are expected to be published soon.

The results of the experimental study confirmed the adequate stiffness, strength and load carrying capacity of the aluminium bridge deck panel under static load. The stress state under the load patch is significantly influenced by localized bending. This influence is so strong that evolution of the failure regions is ultimately determined by these local effects. The HAZ material close to weld toes is potential weak point. Strength in the heat affected zones is significantly reduced and fracture initiated at these locations. The failure mechanism and the failure load were identified during the tests, showing the adequate safety margins of the panel. In the first ultimate load test failure occurred at a load of about 560 kN by gross yielding and fracture underneath the load patch. In the second ultimate load test failure load was about 920 kN by fracture of HAZ material close to welds on the bottom deck surface. The results of this research study were in good agreement with the model study carried out elsewhere, see Matteo [3], Okura et al. [4]. Although proprietary constraints prevented a specific comparison, the stress and displacement distribution and magnitudes were very similar. Results from the study clearly demonstrate that aluminium bridge deck panels are feasible alternative to RC decks from the standpoint of stiffness, strength and load carrying capacity. However, before the panel is recommended for use on deteriorated bridges that need deck replacement, the next two phases of the research study must be completed. An important question remains regarding the structural performance of the aluminium deck system. The long term behaviour under repeated loads and the fatigue resistance of longitudinal welds should be verified both in the laboratory and on-site. The proposals for possible deck panel applications in replacement cases have been recently presented to road administration. The preliminary replacement designs for two structurally deficient and functionally obsolete bridges have also been prepared. Service performance tests will be conducted after the bridges are open to the public in order to estimate service life of the aluminium bridge deck system.