Investigation of the effect of using TADAS dampers in hydraulic structures under continuous loads

TADAS additional dampers are a type of passive control system that can be used in seismic design or retrofitting of offshore structures. The most common type of fixed offshore structures that are used include jacket or template platforms. These dampers in combination with offshore structures through the consumption of a large part of the input energy of the earthquake, greatly reduce the demand for energy loss by the main members of the frame in this type of structures and therefore increase the safety of structures. In the present study, the behavior of TADAS dampers in large displacements in SPD21 platform, which is one of the offshore platforms of South Pars phase 1, was investigated and some possible incorrect details in its design, which if not paid attention can cause damage to the structure, were reviewed and analyzed. To investigate this issue, the TADAS damper was simulated in full detail in the SPD21 offshore structure in ABAQUS finite element software and was subjected to continuous earthquake loading resulting in the large displacements. It was found out that the stiffness of the damper increases sharply and abruptly in a large displacement, which can lead to undesirable responses and even help to destroy the marine structure, and the looseness of the pins delays damper performance and increases the likelihood that dampers will play a lesser role in the earthquakes. In this research, it was deduced that if the height of the TADAS damper gap is increased up to 9 cm and the pins are at the lowest point inside the gap when installing the damper, the TADAS dampers installed on the template platform will be able to withstand the forces of earthquake and large displacements caused by them up to 17.9 cm which will play an important role in the stability of template platform structures such as SPD21 in the event of an earthquake and large displacements.