Structural response behavior of Tension Leg Platforms (TLPs) used in deep sea oil exploration is nonlinear due to large displacements and fluid-structure interaction. Their relative insensitivity in deep sea and excellent station keeping characteristics make them suitable for deep waters, apart from being cost-effective. This study investigates response behavior of TLP with triangular geometry using Dynamic Morison equation; nonlinearities associated with vortex shedding effects are considered in contrast to the standard Morison equation that has undesirable features in this respect. Numerical studies conducted on TLPs under regular waves with varying hydrodynamic coefficients show that the coupled responses in active degrees-of-freedom namely surge, heave and pitch response obtained using Dynamic Morison equation are lesser in comparison to those obtained using standard Morison equation. © 2010 American Institute of Physics.