This paper presents the seismic behavior of hollow-core fiber-reinforced polymer–concrete–steel (HC-FCS) columns. The typical HC-FCS column consists of a concrete wall sandwiched between an outer fiber-reinforced polymer (FRP) tube and an inner steel tube. The inner steel and outer FRP tubes provide continuous confinement for the concrete shell; hence, the concrete shell achieves significantly higher strain, strength, and ductility than unconfined concrete in conventional columns. Three large-scale HC-FCS columns were investigated in this study. Each column had an outer diameter of 610 mm (24 in.) and a height-to-diameter ratio of 4.0. The steel tube was embedded into a reinforced concrete footing with an embedded length of 1.6–1.8 times the steel tube diameter, whereas the FRP tube only confined the concrete wall thickness and truncated at the top of the footing level. In general, the columns exhibited high lateral drift, reaching to 11.6%, and failed gradually as a result of concrete crushing and local steel tube buckling. An equation to determine the steel tube development length of HC-FCS columns was introduced based on an extensive finite-element study. The finite-element analysis was validated with finite-element models. In addition, this paper introduces a quick-repair technique for HC-FCS columns. Guidelines for the preliminary design of HC-FCS columns under seismic loading are also presented to help implement this new technology.

Accidental collisions involving over-height trucks that exceed vertical clearance limits and bridge superstructures frequently happen, resulting in compromised girders and potential threats to structural safety and performance. The numerical simulation of large-scale prestressed girder bridge collisions poses challenges due to the associated nonlinearities, as well as the limited availability of large-scale experimental testing data in the literature due to cost and complexity constraints. This study introduces a numerical modeling approach to efficiently capture the response of prestressed girder bridges under lateral impact loads. A finite element (FE) model was developed using LS-DYNA and meticulously validated against experimental data from the literature. The study explored four methods for applying prestressing forces and evaluated the performance of four concrete material constitutive models, including the Continuous Surface Cap Model (CSCM), Concrete Damage Plastic Model (CDPM), Karagozian & Case Concrete (KCC) model, and Winfrith concrete model, under impact loads. Furthermore, an impact study was conducted to investigate the influence of impact speed, impact mass, and prestressing force on the behavior of prestressed girder bridges. Utilizing the dynamic relaxation (DR) approach, the developed FE model precisely captured the response of prestressed girders under impact loads. The CSCM yielded the most accurate predictions of impact forces, with an error of less than 8%, and demonstrated a strong ability to predict damage patterns. Impact speed, mass, and the presence of prestressing force showed a significant influence on the resulting peak impact force experienced by the girder. Furthermore, the study underscores the composite nature of the bridge’s response and emphasizes the importance of analyzing the bridge as a whole rather than focusing solely on individual girders.

This article presents a numerical study on the behavior of hollow-core fiber-reinforced polymer–concrete–steel (HC-FCS) columns under combined axial compression and lateral loadings. The investigated HC-FCS columns consisted of an outer circular fiber-reinforced polymer (FRP) tube, an inner square steel tube, and a concrete wall between them. The HC-FCS column has several advantages over RC columns. The tubes act a stay-in-place formwork, providing continuous confinement and reinforcement. The concrete shell prevents the outward buckling of the steel tube, which improves the column strength. Three-dimensional (3D) numerical models were developed and validated against experimental results. The models subsequently were used to conduct a parametric finite-element (FE) study investigating the effects of the concrete wall thickness, steel tube width-to-thickness (B/t_s) ratio, confinement ratio, concrete strength, applied axial load level, and buckling instabilities on the behavior of the HC-FCS columns, with a particular emphasis on local buckling of the inner tube. This study revealed that the behavior of HC-FCS columns is complicated due to the interaction of the stiffness of the three different materials: concrete, steel, and FRP. In general, in the HC-FCS columns with square steel tubes, failure was triggered by local buckling of the steel tube followed by FRP rupture. The presence of the concrete wall restrained by the outer FRP and inner steel tubes significantly affected the steel tube buckling. Expressions were also developed to predict the local buckling stresses and strains of the square steel tube.

This paper presents the behavior of hollow-core fiber-reinforced polymer–concrete–steel (HC-FCS) columns under cyclic torsional loading combined with constant axial load. The HC-FCS consists of an outer fiber-reinforced polymer (FRP) tube and an inner steel tube, with a concrete shell sandwiched between the two tubes. The FRP tube was stopped at the surface of the footing, and provided confinement to the concrete shell from the outer direction. The steel tube was embedded into the footing to a length of 1.8 times the diameter of the steel tube. The longitudinal and transversal reinforcements of the column were provided by the steel tube only. A large-scale HC-FCS column with a diameter of 24 in. (610 mm) and applied load height of 96 in. (2438 mm) with an aspect ratio of four was investigated during this study. The study revealed that the torsional behavior of the HC-FCS column mainly depended on the stiffness of the steel tube and the interactions among the column components (concrete shell, steel tube, and FRP tube). A brief comparison of torsional behavior was made between the conventional reinforced concrete columns and the HC-FCS column. The comparison illustrated that both column types showed high initial stiffness under torsional loading. However, the HC-FCS column maintained the torsion strength until a high twist angle, while the conventional reinforced concrete column did not.

This review assesses the validity of a biomechanical approach using finite element analysis in the Thoracolumbar Injury Classification and Severity Score System (TLICS) by addressing the “gray zone” decision discrepancy of thoracolumbar spinal injuries. A systematic review was performed using the keywords “Thoracolumbar Injury Classification” AND “finite element analysis of the spinal column” to evaluate the validity of the TLICS and finite element analysis of the thoracolumbar spinal column. Results were classified according to the main conclusions and level of evidence. Thirteen articles are included. Four of the articles evaluated the TLICS in comparison to other classification systems of thoracolumbar spinal injuries. A notable finding is that the TLICS had inconsistencies with other classification systems in the treatment of burst fractures without neurological deficits. One article evaluated the TLICS with the inclusion of magnetic resonance imaging (MRI) in the evaluation, which decreased the agreement between the suggested and actual treatment. Among the three finite element analysis studies, limited data have been published on the posterior ligamentous complex (PLC) status when an injury is suspected or indeterminate. The TLICS has been a reliable classification system in the management of single-column fractures and three-column injuries treated with surgical stabilization. Special attention to enhancing the TLICS classification system by eliminating the “gray zone” of a TLICS score of 4 is essential. Biomedical computational modeling evaluating the PLC status of indeterminate or injury suspected is needed to enhance the current TLICS system and to clarify the decision discrepancy in the “gray zone.”

Steel H-piles are exposed during their service life to wet-dry cycles in combination with salts, such as deicing, that may result in corrosion, leading to cross-sectional loss and reduction in axial load-carrying capacity. This paper proposes an innovative repair method for corroded steel H-piles using ultrahigh-performance concrete (UHPC) plates. The UHPC plates are reinforced with carbon fiber-reinforced polymer (CFRP) grids. The UHPC plates bridge the corroded segment so that the axial force bypasses the corroded segment. The UHPC are bolted to the steel H-pile using high-strength bolt connectors (HSBCs). Eleven steel H-piles bolted with UHPC plates were investigated experimentally under push-out loading to quantify the axial force that can be transferred from a steel H-pile to UHPC plates through HSBCs. The examined parameters were the UHPC plate thickness, the diameter of HSBC, and the number of CFRP grid layers. The results were compared with those predicted using different design codes and guidelines. The UHPC plates attached to the steel H-pile could transfer axial loads ranging from 35% to 98% of the steel H-piles’ ultimate axial capacity. Further, the installation of the UHPC plate on a steel pile can be completed in about 2 h with minimal equipment, making it a promising repair candidate in real-world applications.