1. Iakovos Lavasas Civil Engineer Padelis Zervas Dr. Civil Enginner
Aristotle University of Thessaloniki (AUTH) Institute of Steel Structures
Prof. C.C Baniotopoulos
Iakovos Lavasas Civil Engineer
Padelis Zervas Dr. Civil Enginner
George Nikolaidis Civil Engineer

2. Prestressed anchors Finite Element modelling
Foundation is modeled using brick elements
Anchors are modeled as non-linear tendon elements between the washer plates
Unilateral contact conditions between the washer plates and the pedestal

3. Prestressed anchors
Prestress force is selected in order to eliminate anchor tensile force variation under operating wind loads
Special concrete reinforcement is needed to carry the splitting forces on the concrete pedestal

4. Seismic hazard Mass distribution Types of analysis
Concentrated on the top of the tower with eccentricity
Distributed over the tower height
Types of analysis
Eigenvalue analysis
Rensponse spectrum analysis
Eigenvalue analysis is also significant for the fatigue design

5. Seismic hazard
X,Y rotation spectra must be considered together with relevant translation spectra (EC8-3 Annex A).
Soil-structure interaction must be taken into account in eigenvalue analysis

6. Seismic hazard
Usually seismic loads are smaller than the extreme wind loads
This is not obvious when constructing in a seismic hazardous area.
A simplified linear model can also give satisfactory results on eigenvalue analysis but not on seismic tower design

7. Ring stiffeners
Ring stiffeners are placed to reduce the local buckling of the shell
Local buckling is produced by
Meridional compressive stresses  Lower part of the tower
Circumferencial compressive stresses  All over the tower height
According to EC3-1-6 buckling design, ring stiffeners are dividing the
tower into sections
Local buckling is taking place in every section

8. Ring stiffeners
Ring stiffener disturbance along the tower is significant for the optimization of the design
Stiffeners should be placed in order to equate (as possible) the total design ratios for every part of the tower
Design ratio
Tower parts between stiffeners

9. Door stiffeners Scope:
Smooth the stress concentration around the door opening
Reduce local buckling
Stress concentration around the door opening