Technics
Bridge solutions
Push test
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In accordance with the new requirements of the Belgian legislation (PTV869 ), in situ push tests may be carried out in order to test the resistance of the base concrete. This will improve device behavior by maximizing safety and minimizing maintenance.
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Transmitted forces
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The transmissible forces were calculated at the ultimate limit state as defined in standard NBN EN1317-1:2010, from which the extract is shown below:
“The vehicle restraint manufacturer must provide details of the maximum forces that can be transmitted by the anchorages to the foundation. These maximum forces shall be those generated by any conceivable impact at the ultimate limit state of the vehicles restraint system, including the structure edge barrier, and shall normally be greater than those which may be observed during shock. Therefore, the ultimate forces that can be transmitted to the bridge deck must be obtained by calculations or by ad hoc tests.”
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In addition, it should be noted that restraint systems that transmit the least effort result in substantial savings on bridge refurbishment. However, it must be ensured that these devices also have a reduced maintenance. To do this, we will ensure that in case of accident does not lead to a kerb reparation.
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On bridges, DOLRE barriers offers the lowest transmitted forces on the market.
Evaluation of bridge resistance
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To estimate the capacity of a bridge to contain the forces transmitted by DOLRE the internal design office DESAMI can calculate the stresses in the bridge deck using a finite elements software.
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The modeling and calculation of the stresses of the reinforced concrete structure make it possible to determine the necessary reinforcement.
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Laboratory tests combined with Eurocode calculations make it possible to define the ideal beam ensuring the connection between the deck and the barrier post.
Anchor testing
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The anchorages are design so that when the failure of the column is reached, the tensile stresses in the anchorages are lower than the guaranteed minimum elastic limit of these.
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After installation it is possible to submit the most stressed anchor in the event of an impact to a tensile stress (confined pull-out test). The force applied will be that which results in a stress corresponding to the guaranteed elastic limit of the anchorage. The test is therefore non-destructive.
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The tests are carried out on 10% of the posts. In the event of a break, all the anchors in the sealing campaign must be checked.
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This type of test can also be carried out on a structure. It is a question of pushing on the head of the post and bringing it to faillure without damaging either the anchoring or the bridge. This type of test, which is easy to perform, offers an excellent technical guarantee as to the proper functioning of the device.