Publication ATG texts - Foundation piles
BCCA has developed a new scheme for the Technical Approval (ATG) with certification for foundation piles. To this end, a collaboration has been set up between experts from different fields: SECO, Buildwise and some independent experts in the field of foundation piles. The launch of this system took place at the request of the market itself.
In Belgium, the calculation of the theoretical bearing capacity of foundation piles should be based on the rules of NBN EN 1997-1, the corresponding Belgian annex (ANB) and until recently the WTCB report 12/19 (now “Buildwise dimensioneringsmethode” 12 and 19). In this report the use of some favorable factors (installation factor, model factor, safety factor) was linked to the presence of a quality system, the conformity with “info files” published by Buildwise and the execution of instrumented pile tests.
ATG with certification
However, compliance with these quality conditions was not verified by an independent third party. This possibility was integrated into the new document “Buildwise dimensioneringsmethode 20” through the use of Technical Approvals (ATG) with certification.
These changes will have an immediate impact on the design of soil displacement screw piles, CFA piles and micropiles, as well as other foundation- and anchoring systems in the future. In order to minimize the market disruption, it was opted to group all applications per type and publish them as a group. In this 1st phase, the soil displacing screw piles are treated.
Initial investigation
The initial process to obtain an ATG with certification includes an approval and certification part. During the approval investigation, the technical requirements of the product within its intended application domain are examined; the certification part includes auditing of the quality system to see how the producer can guarantee the quality on a continuous basis.
To ensure the equivalence between all demands, an approval guideline (GKL) and application rules for certification (TRA) were drawn up. An initial examination was conducted for all submitted demands:
- The used calculation method (according to “Buildwise dimensioneringsmethode 20”) was verified via a benchmark calculation.
- To support the improved coefficients, the manufacturer was also able to supply instrumented pile tests in his dossier. These test data were analyzed in relation to the compliance with the requirements of the approval guideline.
- The producer's quality system was audited and any remarks were followed up through an action plan.
- To verify the application of the internal procedures and work instructions, site inspections were carried out. During these inspections, a number of pile installations were monitored.
Publication
Based on the above evaluation of the rules described in the GKL and TRA, 12 ATG dossiers (soil displacement screw piles) from 8 different producers were retained and published as ATG text on 02/05/2023. As of today, the follow-up phase of these ATG’s starts with audits, technical visits and site inspections.
The ATG texts can be consulted on the following website:
Save the date !
On 25/05/2023, an information session will be organized by the BGGG in cooperation with BCCA, Buildwise, SECO and ABEF at Buildwise Zaventem to explain the ATG framework and clarify the implications for design, and this from the point of view of clients, engineering offices, general contractors and deep foundation contractors.
https://www.bggg-gbms.be/nl/bijeenkomsten/detail/21/infosessie-atg-funderingspalen
In the meanwhile, the GKL and TRA are updated to start the approval process for CFA piles. As soon as these ATG texts are published (target: end 2023 / beginning 2024), the processing of the applications concerning the micro-piles will be started.