Vibrations of complex structures such as bridges mostly present nonlinear and non-stationary behaviors. Recently, one of the most common techniques to analyze the nonlinear and non-stationary structural response is Hilbert–Huang Transform (HHT). This paper aims to evaluate the performance of HHT based on complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) technique using an Artificial Neural Network (ANN) as a proposed damage detection methodology. The performance of the proposed method is investigated for damage detection of a scaled steel-truss bridge model which was experimentally established as the case study subjected to white noise excitations. To this end, four key features of the intrinsic mode function (IMF), including energy, instantaneous amplitude (IA), unwrapped phase, and instantaneous frequency (IF), are extracted to assess the presence, severity, and location of the damage. By analyzing the experimental results through different damage indices defined based on the extracted features, the capabilities of the CEEMDAN-HT-ANN model in detecting, addressing the location and classifying the severity of damage are efficiently concluded. In addition, the energy-based damage index demonstrates a more effective approach in detecting the damage compared to those based on IA and unwrapped phase parameters.

Reinforced concrete structures and structural members used in strategic infrastructures such as highway bridges, high-rise buildings, etc. are inherently subjected to lateral impact loads arising from the collision of vehicles, vessels, falling rocks, and rigid objects having different impact geometries, weights, and velocities. Due to the brittle nature of concrete materials, both localized and overall failure modes are very likely to occur in concrete structures under dynamic and impulsive loads. Hence, many attempts have been carried out in the literature to recognize the failure behaviors and to assess the vulnerability of concrete structure under lateral impact loads. This paper presents a comprehensive state-of-the-art review on the responses and failure behaviors of various types of concrete structures and structural members subjected to lateral impact loads based on analytical, numerical, and experimental studies carried out by the previous research works. In addition, the influences of various structural- and load-related parameters on the impact resistance and failure behaviors of different concrete structures under lateral impact loads are reviewed.

This paper aims to numerically evaluate the effects of girder bridge superstructure on the impact responses and load paths transferring the shear force of pier subjected to a moderate-energy barge collision in LS-DYNA. First, two multiple-pier systems of St. George Island Bridge in Florida which have different piers in terms of structural characteristics (such as mass and stiffness), geometry, and the height of impact location are considered as the cases of study. From the numerical barge collision simulations, different impact responses and load transferring paths from the impact location to farther zones are observed. In addition, the sensitivity of impact responses, and the impact load paths transferring shear force to the superstructure mass, stiffness, and damping are studied by developing four different models of pier-superstructure interaction and carrying out a parametric study. It is found that the increase in the value of superstructure parameters has positive effects on the impact forces and the internal stresses in the piers. However, the sensitivity of shear stresses generated at various zones of the pier extremely depends on the impact load paths transferring shear force in different piers with different relative characteristics rather than the superstructure.

This paper aims to probabilistically assess the multiple failure modes of the piers of St. George Island Bridge subjected to barge collisions using the correlation analyses of failure limit states at various section zones. Structural capacities and demands for internal shear forces and flexural moments are calculated using the finite element modelling software, LS-DYNA, and the reliability assessments are performed using Monte Carlo simulations against flexural and shear failures. From the results of reliability analysis, the base and impact zones for the isolated cases, and the top zone of impacted piers in the multiple-pier systems are recognized as the critical zones for localized failures of the piers. In addition, from the statistical correlation analysis, it is found that a shear failure mode is predominant on the relatively stiffer pier, a flexural failure mode on the more flexible pier in the isolated cases, and a combined shear-flexural failure mode on the response of the piers in multiple-pier systems. Moreover, from a series of sensitivity analyses of reliability indices to both shear and flexural failures by varying impact loading parameters, it is found that the shear failure is more sensitive to the impact variables rather than flexural failure.