beams;  deflection;  Fault diagnosis;  System identification

The damage diagnosis and analysis of building structures is the basis for structural performance evaluation. The static detection method is used to analyze the damage diagnosis problem of beam components. According to the change of the equivalent flexural stiffness of the beam section, the mechanical model of the beam is established, and the damage diagnosis and analysis method of beam members is established based on the deflection change of the beam under concentrated load, and based on the principle of system identification. Through example calculation, it shows that the proposed method has good convergence and stability.