Prediction of structural instability of along-span bridge is usually conducted in a wind tunnel test, where the aerodynamic as well as aeroelasticaspect of the structure can be tested by means of 2 or 3 dimensional model. In a 2 dimensional model, inspite of testing the physical model, a mathematical model should also be constructed. Initially, this mathematical model has unknown parameters that must be determined from experimental data. In otherwords, the determination of aerodynamic coefficients is part of system identification of aeroelasticequations for predicting the critical margin of the bridge structure. The following paper will describe thedevelopment of a software tool for extracting the aerodynamic coefficients of a sectional model test (2 dimensional) in the ILST (Indonesian Low Speed Tunnel). Keywords: long span bridge, wind tunnel testFariduzzaman; UPT-LAGG BPPT, PUSPIPTEK, Tangerang-15314, INDONESIA farid@lagg.or.id
