Performance Of Reinforced Concrete Bridge Columns Research Articles

Computational modeling and dynamic response of highway bridge columns subjected to combined vehicle collision and air blast

Vehicle impacts into supporting bridge columns can cause significant damage and, when combined with an air blast, could result in, at best, an unsafe situation for the bridge or, at worst, complete collapse. Limited studies have been conducted that investigate the response of bridge substructure units subjected to a combined collision and blast loading. This paper summarized results from a numerical study examining the response of highway bridge columns subjected to a combined vehicle collision and air blast using LS-DYNA, the computational tool used for this research. Numerical models consisting of a circular reinforced concrete (RC) bridge column, its pile cap and pile foundation system, and a surrounding soil volume were developed and validated. Validated models were then subjected to simulated impacts from a Ford F800 Single-Unit Truck (SUT) and air blasts represented using a Multi-Material Arbitrary Lagrangian-Eulerian (MM-ALE) formulation with applied blast loads being taken from the fluid-structure interaction (FSI) algorithm in LS-DYNA. The validated computational modeling technique presented in this study provides a vital source for producing information in the combined collision and blast design field and determining the combined impact-blast behavior of bridge columns. A detailed investigation was performed to determine a critical impact and blast sequence for this research study. Furthermore, numerical simulations of SUT collision with RC column coupled with air blast were conducted considering variations of vehicle velocity, blast scaled distance, and column diameter. The demand and performance of RC bridge columns were examined with representative damage categories identified in this study to provide insights on column design to withstand the collision and blast combination.

DAMAGE-CONTROLLABLE STRUCTURE SYSTEMS USING FRP COMPOSITES

Today, key infrastructures are required to have usability and repairability after earthquakes. Based on the requirements of the new codes, a mechanical model of damage-controllable structure using fiber reinforced polymers (FRPs) is proposed. Hence, the aim of the study is to examine the required recoverability for existing and new structures. First, an intensive study on the inelastic performance of FRP-retrofitted bridge columns was conducted. The study showed that recoverability of such columns is probable. Subsequently, an advanced FRP-strengthening design guideline that considers and evaluates structural recoverability is proposed. Second, innovative reinforcing rebars (steel fiber composite bars (SFCBs)) were developed to enhance the post-earthquake recoverability of new reinforced concrete (RC) bridges. The performance of RC bridge columns reinforced with two types of the innovative rebars, i.e. steel basalt-fiber composite bar (SBFCB) and steel carbon-fiber composite bar (SCFCB), were experimentally studied. Furthermore, numerical studies were conducted to investigate the performance of bond-controlled structures reinforced with the innovative rebars. Experimental results showed that SFCBs, as longitudinal reinforcement, guarantee the gradual increase of column strength in the inelastic stage and substantially mitigate column residual deformations. In the light of the analytical results, concrete-to-SFCB bond would be a reasonable tool to control the required recoverability, where both column post-yield stiffness and residual deformations could be controlled.