The growing population and increasing demand for surface transportation have highlighted the importance of maintaining safe and reliable civil infrastructures for daily use. Among all civil infrastructures, bridges are one of the most important elements in the transportation system. As such, to prevent any failures caused by aging and environmental impacts, bridges require periodic inspections. This becomes even more critical due to climate change and its effect on bridges, especially in the coastal regions. Most of the inspections conducted incorporate the visual type of evaluation due to its simplicity. However, with the current developments in new technologies, there is a need for more advanced techniques of structural health monitoring (SHM) methods to be incorporated in the maintenance programs for more accurate and efficient surveys. In this paper, non-destructive testing (NDT) methods applicable to steel bridges are reviewed, with a focus on methods applicable to local damage detection. Moreover, the methodology, advantages and disadvantages, and up-to-date research on NDT methods are presented. Furthermore, the application of novel NDT techniques using innovative sensors, drones, and robots for the rapid and efficient assessment of damages on small and large scales is emphasized. This study is deemed necessary as it compiles in one place the available information regarding NDT methods for in-service steel bridges. Access to such information is critical for researchers who intend to work on new or improved NDT techniques.

Normally, Laminated Rubber Bearing Pads (LRBPs) are directly placed between girders and piers and their role is to provide the bridge span with horizontal movement, and to transmit the gravity loads from the deck to the piers. Although not designed for seismic loads, they can act as a fuse, partially isolating the substructure from the superstructure and keeping the piers intact during earthquakes. However, recent investigations show that large relative displacement of superstructure against substructure caused by sliding at bearing (sliding between girders and LRBPs) can cause expansion joint failure or even bridge span collapse. Accordingly, proper restrainers should be selected to prevent large displacement. Among all types of restrainers, viscous dampers as passive energy dissipation devices have shown a great capacity in damping earthquake energy. This study investigates the effectiveness of a VD-LRBP system, a viscous damper in conjunction with LRBPs, in dissipating energy and reducing the displacement of the superstructure with reference to the substructure caused by sliding at bearing during a seismic event. A Finite Element (FE) model was first developed and validated using available experimental and numerical results. With the validated model, a 3D Nonlinear Time History Analysis (NTHA) was conducted on a reinforced concrete bridge model under various records of earthquakes using OpenSees, an open-source finite element software. The relative displacement histories were recorded for the bridge in two cases: 1- with only LRBPs and 2- with viscous dampers and LRBPs (VD-LRBP system). The results of this study show that applying viscous dampers can reduce the relative displacement of the superstructure with reference to the substructure for up to 60 percent. As importantly, it can also reduce the residual displacement after the earthquake to near zero.

Post-earthquake evidence shows that shear failure in non-ductile detailed columns is a major source of structural collapse and earthquake deaths. Nonlinear cont

Laminated rubber bearing pad (LRBP) is widely used in small to medium-span highway bridges. They are directly placed between piers and girders to allow the bridge span to have horizontal movement and to transfer the gravity loads from decks to piers. Although LRBPs are not designed for seismic loads, their application can partially isolate the superstructure from the substructure keeping the piers intact during earthquake events. However, recent investigations indicate that large relative displacement between superstructure and substructure caused by sliding between girders and LRBPs can cause expansion joint or bridge span failure. As such, suitable restrainers should be implemented to control the potential large displacement. Among all types of restrainers, passive energy devices such as viscous dampers have shown a remarkable capacity in dissipating the earthquakes energy. This study aims at investigating the effectiveness of VD-LRBPs system, viscous dampers in conjunction with LRBPs, in controlling the large displacement between decks and piers. Accordingly, a 3D Nonlinear Time History Analysis (NTHA) was conducted on a case study RC bridge model under several earthquakes. OpenSees, an open sources finite element software, was used for the analysis. The relative displacements between decks and piers as well as the force in the piers, were recorded for two cases: 1- with only LRBPs and 2- with viscous dampers and LRBPs (VD-LRBP system). The results indicate that adding viscous dampers can reduce the relative displacement up to 60 percent. Also, it can reduce the potential residual displacement post-earthquakes to near zero.

Concrete columns are considered critical elements with respect to the stability of buildings during earthquakes. To improve the accuracy of column damage and collapse risk estimates using numerical simulations, it is important to develop a methodology to quantify the effect of displacement history on column force–deformation modeling parameters. Addressing this knowledge gap systematically and comprehensively through experimentation is difficult due to the prohibitive cost. The primary objective of this study was to develop guidelines to simulate the lateral cyclic behavior and axial collapse of concrete columns with different modes of failure using continuum finite element (FE) models, such that wider parametric studies can be conducted numerically to improve the accuracy of assessment methodologies for critical columns. This study expands on existing FEM research by addressing the complex behavior of columns that experience multiple failure modes, including axial collapse following flexure–shear, shear, and flexure degradation, a topic which has been underexplored in previous works. Nonlinear FE models were constructed and calibrated to experimental tests for 21 columns that sustained flexure, flexure–shear, and shear failures, followed by axial failure, when subjected to cyclic and monotonic lateral displacement protocols. The selected columns represented a range of axial loads, shear stresses, transverse reinforcement ratios, longitudinal reinforcement ratios, and shear span-to-depth ratios. Recommendations on optimal material model parameters obtained from a parametric study are presented. Metrics used for optimization include crack widths, damage in concrete and reinforcement, drift at initiation of axial and lateral strength degradation, and peak lateral strength. The capacities of shear–critical columns calculated with the optimized numerical models are compared with experimental results and standard equations from ASCE 41-17 and ACI 318-19. The optimized finite element models were found to reliably predict peak strength and deformation at the onset of both lateral and axial strength failure, independent of the mode of lateral strength degradation. Also, current standard shear capacity provisions were found to be conservative in most cases, while the FE models estimated shear strength with greater accuracy.

This study addresses low-cycle fatigue performance of high-strength steel reinforcement bars (HSRB) when used with mechanical couplers due to the growing demand for higher-strength steel reinforcement bars in both seismic and non-seismic applications, driven by the need to reduce bar congestion, lower material quantities, and consider economic and environmental factors. Low-cycle fatigue involves material failure owing to a finite number of load or deformation cycles, generally occurring under substantial strain rates that surpasses the yielding limit. The experimental program assesses the fatigue behavior of HSRB produced using microalloying, quenching, and tempering techniques, coupled with mechanical couplers (eleven different types) from five companies in the United Stated of America. The study highlights significant differences in fatigue endurance based on the type and make of couplers and suggests potential improvements in manufacturing processes to enhance fatigue resistance. It is found that the mechanical couplers sustain a loading protocol of (-1% to 3%) when there is a clear distance of 2 times the diameter of the bar between the coupler and the gripping machine from top to bottom. The coupled bars sustained a minimum of 6 half cycles and a maximum of 38 half cycles.