Damage identification technique for short-span bridges using representative power spectral density (RPSD) and static moment area (SSM): a case study of the random vibration signals of 38 bridges under random load

In recent years, there has been extensive research on detecting damage or identifying changes in stiffness in structures by analyzing their dynamic properties or responses. The fundamental idea is that damage or loss of integrity in a structural system can affect its response to dynamic forces, leading to changes in properties like eigenfrequencies, modal damping ratios, mode shape, and transfer functions. In Vietnam and some other countries in the Southeast Asia region, the prevailing climate conditions, slow economic development, and geographical location have resulted in the construction of predominantly short-span bridges with a limited number of spans. This is primarily because these bridges connect small channels and waterways. This characteristic provides a basis for developing and applying research findings specifically for this group of bridges, as they are seldom encountered and researched in other countries worldwide. This paper presents a damage identification technique for short-span bridges based on changes in the representative power spectral density (RPSD) and the static moment of area (SSM). The proposed method is applied to experimental data obtained from various bridge models, including prestressed concrete, reinforced concrete, and composite steel bridges. It is important to note that changes in RPSD and SSM are independent of traffic conditions on the bridge but instead rely on the structural and material properties of the bridge spans. By utilizing RPSD and SSM, new advancements can be made in assessing the structural condition of bridges using vibration signals.