abdolrasoul RANJBARAN - Associate professor Department of Civil Engineering, Shiraz University, Shiraz, Iran
mohammad taghi MORAVEJ - Msc candidate Department of Civil Engineering, Shiraz University, Shiraz, Iran

A new method for computation of vertical eigen pairs of high-rise buildings is proposed. Using the calculus of variations, the differential equation and boundary conditions governing the free longitudinal vibration of tall buildings, modeled as a bar, is transformed to an optimization problem. Different techniques of optimization may be used for minimization process. Currently the BFGS algorithm is used. Through analysis of numerical examples and comparison of the results with full scale measured data the method is verified. The proposed method is more accurate, efficient, general, and simple than the methods in the literature.