# Preloaded anchors (WP 1.4 background document presentation) Institute of Steel Structures Aristotle Univ. of Thessaloniki.

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Preloaded anchors (WP 1.4 background document presentation) Institute of Steel Structures Aristotle Univ. of Thessaloniki

Preloaded anchors Configuration Configuration Partially prestressed anchors in Partially prestressed anchors in circumferencial direction Base & embedded washer plates Base & embedded washer plates No contact between the anchors & the concrete No contact between the anchors & the concrete

Preloaded anchors Finite Element model (Foundation section)‏  Concrete & shrink-mortar : Brick elements  Washer plates : Plate elements  Anchors : cable type elements active only in tension  Unilateral contact to the ground

Preloaded anchors Finite Element model (cross-section to the foundation)‏

Preloaded anchors Finite Element model (anchoring detail)‏  Each anchor is a single element connecting only the washer plates (active in tension)‏  Unilateral contact conditions between the base washer plate and the shrink mortar & between the embeded washer plate and the concrete

Preloaded anchors Non-Linear analysis Wind loading combinations  1 st iteration step: Self weight of the tower is applied  Apply anchor prestress step by step  Step by step apply loads for the specific load combination Seismic loading (spectral response analysis not compatible with nolinearities)‏  Solve the spectral response case, the tower rigidly connected to the foundation  Determine forces acting on the pedestal using SRSS comb.  Construct a new model for the foundation only incorporating all non-linearities  Execute the iterative analysis as above, applying the reactions of the tower to the foundation.

Preloaded anchors Design of the foundation-anchoring system  Washer & base plates (Von mises stresses)‏  Prestressed anchors (tensile forces)‏  Non-shrink mortar (compressive & shear stresses)‏  Concrete (compressive,shear & punching shear stresses)‏  Reinforcing bars  Rigid body equilibrum for the structure

Preloaded anchors Reinforcement check points Reinforcement check points 1,2 : Footing, bottom mesh 3,4 : Footing, top mesh 5 :Top of pedestal mesh 6 :Pedestal vertical rebars (transfer of tensile anchor forces)‏ 7 :Circumferencial reinforecement (split-up forces)‏

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