Appraisal of loads from wind and off-shore Sea on platforms converted to the electric power production with wind turbine

“Appraisal of loads from wind and off-shore Sea on platforms converted to the electric power production with wind turbine” Michele Rizzo1,*, Ostilio Spadaccini2, Andrea Vignoli3, Luca Facchini4 Department of Civil Engineering, University of Florence, Via di S. Marta, 3 – 50139 Firenze 1Ph.D.,C.E. Student, 2-4Associate Professor, 3Full Professor *Correspondent Author: phone 0554796326, e-mail: mrizzo@dicea.unifi.it Abstract In the present work due to the interaction with the sea have been carried out the elaborations necessary in order to gain forcing to apply to one off-shore structure and to that one with the wind; in particular a series of waves generated from the wind has been obtained with ‘teoria del quasi-determinismo’, and famous the field of speed and pressures around the immersed poles have been obtained the forces distributed with the formula of Morison, while for how much it concerns the wind has been studied the interaction of the vertical structures (support poles antennas and pole of support turbine) and with the shovels of the wind turbine with ‘Blade element theory’. In particular, the carried out analysis has been proposed to apply such methodologies to the called off-shore structure T1 (isolated wharf for cargo and drainage hydrocarbons) situated to the wide one of the Adriatic coast of the port of Ravenna. The proposed analysis has been executed on the structure to the state puts into effect them and to the state in plan, that is with one wind turbine with beam of 20 m mounted on the pole of support to the quota 80 m L.A.T.. The several analysis be carry out in the several configuration of plan of the turbine, that is that one with a wind with vaverage=12 m/s and turbine in service, with vaverage=20 m/s and turbine in service, with vaverage=32 m/s and turbine outside service. Finally, it has been carried out a fatigue analysis of the stressed structural members more. The carried out analyses evidence the circumstance that in centre puts into effect them the structure turns out much sensitive one allies actions due to the waves of the sea that cross it, in particular the greater actions beginning from derives from the generated action a speed of the wind of equal reference to 12 m/s that structure generates a wave with fundamental period (5,16 s) close to the first fundamental period of vibration of the structure (4,40 s); the actions of the wind on the superstructure in these conditions are negligible. During plan the caused stress configuration from the wind turns out preponderant regarding that one caused from the actions of the sea for the dimensioning of the pole of support of the turbine; the condition worse for the dimensioning of the pole is that one with a wind of reference of 20 m/s, regimen of speed in which the turbine is operating. As far as the reticular structure of foundation the condition worse turns out that one with the generated waves beginning from a speed of reference of 32 m/s, and the poles more speed up to you turn out those inner ones that they are not bound from the counter wind structures. In this configuration of plan the fundamental periods of due to the waves of the sea (5,16 s for vref=12 m/s are not found different phenomena of dynamics amplification between the three the forcing speeds of reference in how much m/s, 6,92 s for vref=20 m/s, 8,75 s for vref=32 m/s), are all remarkably higher of the fundamental period of the structure (2.81 s).