Structural Damage Detection in Double-Tapered Steel Beam Using Modal Strain Energy Method

Structural failures can be prevented by appropriate retrofitting techniques provided if the damage was detected at the early stage. Toward this end, this paper presents a damage detection procedure for double-tapered beams using modal strain energy (MSE) method. The beam is modeled using 2D plane stress element in OPENSEES software. Enhanced quad elements are used for discretizing the tapered beam. The damage is induced in the selected elements by reducing the modulus of elasticity in the beam. The first twenty-five mode shapes are extracted for both undamaged and damaged beams. The extracted natural frequencies of the undamaged double-tapered cantilever beam are compared with the classical approach reported in Mabie and Rogers (1972). The obtained natural frequencies are in agreement with the results reported in the literature. The extracted mode shapes of undamaged and damaged beams were utilized in the MSE method to detect and quantify the single and multiple damaged scenarios. MATLAB code is prepared to estimate the damage index using MSE method. The results indicate that, MSE method is efficient in detecting the damaged elements in beam.