The main span of a bridge structure is considered as a single-degree-of- freedom (SDOF) system for calculation of its fundamental frequency. From preliminary vibration tests, the effective mass of the structure was determined to be 400000 kN and the effective stiffness to be 40000 kN/m. The ratio of successive displacement amplitude from a free vibration trace was measured to be 1.25. Calculate the values of the structural damping coefficient and the equivalent viscous damping coefficient.