Load bearing structural members in a wide variety of applications accumulate damage over their service life. Structures require complicated element models with a number of degrees of freedom in structural analysis. During experiment much effort and cost is needed for measuring structural parameters. The sparseness and errors of measured data have to be considered during the parameter estimation of structures. In this paper we introduces parameter estimation algorithm by a system identification(S.I) using static response. The equation error estimator(EEE) and response error estimator(REE) widely used in system identification are based on the minimization of least squared error between measured and calculated responses by a mathematical model of a structure. In working with static displacements as the measured response, if the applied loads are such that some members of the structure do not participate in the load bearing process, damage in these members would be difficultto detect. The use of a hypothetical load which would induce an equivalent stress distribution load in the structure is proposed as a solution to this problem. The assessment results by each method were compared and we could observe that the S.I method is superior to the other conventional methods.