Jordan Journal of Civil Engineering

Damage Characterization in Building Structures Due to Blast Actions


B. Ahmed; F. Dinu; I. Marginean;


Structural identification is a technique that can be used to assess/characterize the damage state through the variation in eigenfrequencies, damping ratios and modal shapes in a structure or element. It has recently received more attention for the practical implementation in several fields, including damage assessment for structures following blast or explosion events. At present, large infrastructure components, like civil engineering structures, are the most convenient issue of consideration for structural identification. Structures can be moderately or severely deteriorated due to accidental or intentional blasts or explosions. Structural engineers and other stakeholders, like rescue and emergency agencies, are more concerned about the design of structures, design life span, proper maintenance, repair and residual capacity of structural systems in many countries. This research work focuses on the experimental and analytical modal analysis of a full-scale steel frame structure building aiming to develop coherent scenarios that combine the probability of the hazard event with the structural vulnerability in case of a close-in detonation. Field tests were carried out by forced vibration testing under hammer excitations. First, a series of tests were conducted for the undamaged structure using classical experimental modal analysis. Then, in order to model a structural damage, a secondary beam was dismantled (thus a damage was created artificially) and the measurements were repeated. The change in structural behaviour was observed by identifying the changes in the stiffness and natural frequencies of the structure. The modal parameters measured from field tests were then used to validate finite element models using SAP2000 program. They were corrected, so that the numerical natural frequencies and mode shapes match the experimental data. Good agreement was found in identifying the frequencies for the threedimensional finite element models for both damaged and undamaged structures. Then, using the calibrated numerical model, several blast- induced damages were used in a numerical study. For the internal damage or non-visible crack, four different damage scenarios were made by the FE model for internal and external blast actions. The modal parameters changed significantly for higher modes for higher reduction of stiffness at the column-beam and base connections. The results (experimental data, calibrated numerical model) can be used as reference values of the undamaged structure for further investigations after blast tests.


SHM, Modal parameters, FEM modelling, Damage characterization, EMA.