Name of OHTL

Les Ancizes - Volvic - FRANCE

Voltage of OHTL



Linuhönnun (now EFLA) design - CTBA subcontractor for wood issues

Duration of assignment

01.2004 - 12.2005

Value of service

160 k€

The aim of the project was to design a single circuit suspension tower family composed of X-brace wooden H-frame (two types K and N) for the 225kV OHL Les Ancizes - Volvic crossing the Auvergne's volcanoes Natural Park.

With the load cases generated from the tower spotting and the climatic conditions, we determined the designing data, and then designed the towers, made of two wood poles (Pinus Sylvestrus), two cross arms made of doubled UPN profiles and an X-brace made of RHS profiles.

Design has been checked with FEM software SAP 2000 with non linear analysis to take into account the P-Delta effects which are of great importance for such flexible structures.

HECLA supervised the trial assembly on supplier factory site and designed the loading schedule for the real size test carried out at the Lecco test station, in Italy, which allowed the design validation.

One of the design specificity was the connection device between the poles and the foundations, made of two steel half shell of 1,50m high with adjustable compression plates, the wooden poles being undressed (no cropping at their bases).

Design has been made in partnership with LINUHÖNNUN (now EFLA), assisted by CTBA for its knowledge of wooden materials. In addition, HECLA managed the coordination of the studies and the design review, and the supervision of the trial assembly and the real size test.