A new bridge bent system has been developed to reduce on-site construction time, minimize residual displacements even after a large earthquake, and reduce seismic damage in comparison with conventional cast-in-place construction. Accelerated construction is achieved through the use of precast columns and cap beams that can be assembled quickly. Postearthquake residual displacements are reduced by pretensioning the columns with partially unbonded tendons. Damage in the columns is nearly eliminated by concentrating flexural deformations to specially detailed regions at the top and bottom of the columns. In this study, the seismic performance of the new system was evaluated with a multi-shaking table test of a quarter scale, two-span bridge at the Network for Earthquake Engineering Simulation (NEES) Earthquake Engineering Laboratory at the University of Nevada, Reno. The maximum displacements of the bents were similar to those expected for a conventional bridge through the 100% design-level event [p...

Rocking columns reinforced with unbonded prestressing offer advantages for bridges constructed in seismic regions because they can recenter the structure after an earthquake. Under lateral load, the columns rock on the foundation and cap beam, and rotate as rigid bodies rather than deforming. This paper describes cyclic load tests of two subassemblies representing parts of a bridge bent constructed using precast pretensioned rocking columns, spread footings, and a precast cap beam. The subassemblies, representing two halves of a single column, were subjected to cyclic lateral displacements of increasing amplitude under a constant vertical load. The proposed column design has several advantages over conventional cast-in-place construction. The use of precast columns and cap beams reduces on-site construction time. The use of unbonded prestressing minimizes residual displacements after an earthquake. The strands are deliberately debonded through the clear height of the column and bonded to the column concrete at the top and bottom, where the column is embedded in the cap beam and footing, respectively. The columns are confined by steel tubes and annular end plates at their interfaces with the footings and cap beams to minimize concrete damage when the columns rock. In the tests, the columns returned to their initial location with essentially no concrete damage after being displaced to peak drift ratios exceeding 10%. At the end of the tests, the columns’ lateral strengths still exceeded 80% of their peak values. The tests also provided the opportunity to evaluate practical procedures for proportioning key details of the system.

Macro-synthetic fibers are increasingly used in concrete as secondary reinforcement to control temperature and shrinkage cracks, improving durability by limiting crack widths. However, their impact on the shear strength of structural elements remains underexplored, particularly when used in combination with traditional steel reinforcement. To address this knowledge gap, this study developed and calibrated a non-linear numerical model to simulate the shear response of macro-synthetic fiber-reinforced concrete (PFRC) elements, using finite element software VecTor2. The model was calibrated with experimental data from PFRC panels subjected to pure shear loading, incorporating a custom concrete tension-softening model to capture the contribution of fibers. Validation against a broad range of PFRC beam experiments from the literature demonstrated the model’s accuracy, achieving an average predicted-to-experimental shear strength ratio of 0.99 (COV = 5.5%). Additionally, the model successfully replicated key response characteristics such as deformation patterns, crack propagation, and residual strength. The proposed modeling approach provides valuable insights into the interaction between fiber volume and transverse reinforcement. It also serves as a powerful tool for future numerical studies, addressing the existing data gap on PFRC behavior and exploring the synergistic effects of macro-synthetic fibers and steel reinforcement on shear strength.

The United States faces significant challenges with its aging infrastructure, which is both deteriorating and expensive to maintain and rehabilitate. Bridges, being core components of connecting communities and facilitating trade, receive considerable attention from the public and government agencies. However, the traditional ways of monitoring bridge health conditions, often reliant on visual inspections, are inadequate for ensuring their sustained performance. In recent years, the concept of digital twins offers innovative solutions that have the potential to transform the ways the industry can monitor the structural performance of bridges. This approach pairs physical assets with their digital counterparts, leveraging real-time data and simulations to improve the life cycle performance. For example, digital twin technology can enhance the management workflow of bridges and strengthen the decision-making process for replacing bridge components and addressing emergencies by providing real-time status and forecasting future performance. Previous reviews on digital twins in literature have predominantly concentrated on theoretical frameworks and potential industry applications. These studies have not yet engaged in the issues related to implementation and the insights gained from real-world case studies. This research provides insights gained through meetings with stakeholders, practitioners, and professionals involved in a DT proof of technology project. The findings from this research reveal several key design interfaces—both technical and organizational—that pose challenges to the successful implementation of DT systems. This paper aims to contribute to the existing body of knowledge by providing a detailed analysis that highlight the challenges of interoperability and interorganizational collaboration in the creation of system of systems level DTs.

The combined use of macro-synthetic fibers and traditional steel reinforcement in structural concrete shows promise for enhancing shear behavior, particularly with respect to crack control, ductility, and potentially strength. However, experimental data on such systems remain scarce, especially for elements subjected to pure in-plane shear, where the interaction between fibers and conventional reinforcement is not well understood. This study contributes essential experimental evidence toward addressing this gap. Nine reinforced concrete panels were tested under monotonic in-plane shear, with transverse reinforcement ratios ranging from ρ_v = 0% to 0.91%, and macro-synthetic fiber contents from V_f = 0% to 0.52% by volume. Results showed that fibers were highly effective in reducing crack widths at low reinforcement levels. For specimens with ρ_v = 0.34%, increasing V_f from 0% to 0.52% halved the maximum crack width (from 0.6 mm to 0.3 mm) and reduced the average crack width by 22% (from 0.32 mm to 0.25 mm). Potential ductility improvements were also detected at low reinforcement ratios, with increased shear strain capacities observed as fiber content increased. In contrast, the influence of fibers on shear strength was minimal across all reinforcement levels. These findings highlight the potential of macro-synthetic fibers to enhance the performance of shear-critical elements, particularly in lightly reinforced systems, while also illustrating the need for further experimental and numerical work. The results presented here provide a fundamental dataset that can support future efforts to develop reliable assessment and design approaches accounting for the simultaneous presence of steel reinforcement and synthetic fibers in concrete elements subjected to shear.