This study investigates the cyclic behavior of double-tee moment connections without shear tabs using European steel profiles. A three-dimensional finite element model was developed in ANSYS Workbench and validated against experimental results. The model included material and geometric nonlinearities, contact interactions, bolt pretension, and a Chaboche kinematic hardening model to simulate cyclic inelastic behavior. A parametric study examined the effects of T-flange and T-stem thickness, bolt spacing, continuity and doubler plates, reinforcing plates, beam web stiffeners, and circular web openings. Connection performance was evaluated in terms of rotational stiffness, moment capacity, energy dissipation, stress distribution, and plastic hinge formation. Artificial neural network (ANN) models were also developed to predict monotonic and cyclic response parameters. The results show that T-flange thickness and local reinforcement details most significantly improve seismic performance, while bolt spacing has a limited influence. ANN models provided accurate and efficient predictions for preliminary connection assessment.
Urban road networks are critical for maintaining accessibility and emergency response after earthquakes, particularly in densely built areas. This study examines how the spatial pattern of earthquake-induced road blockages affects the structural resilience of a road network in Istanbul. The intact network was compared with two hypothetical scenarios in which the same number of links was blocked, either in a dispersed or localized pattern. Connectivity, intersection density, and changes in network shape across spatial scales were evaluated together. Results show that the spatial arrangement of blocked roads strongly influences network response. Dispersed disruption caused a much larger loss of high-density intersection areas, whereas localized disruption produced a greater reduction in network redundancy while preserving much of the original dense structure. Both scenarios also simplified the spatial organization of the surviving network. Combining these complementary indicators provides a basis for identifying vulnerable road networks and supporting post-earthquake transport planning.
This study investigates the dynamic properties of fiber-reinforced rubberized recycled concrete incorporating recycled coarse aggregate (RCA), crumb rubber (CR), and polypropylene (PP) fiber through free vibration testing. Nine reinforced concrete columns (150 × 150 × 950 mm) incorporating 30% RCA, 0%–15% CR, and 0%–0.5% PP fiber were prepared and tested under three impact energies. The measured acceleration responses were used to evaluate natural frequency, time period, damping ratio, and damping coefficient. Results showed that CR increased the displacement and natural time period. Although the damping ratio increased with CR content, the damping coefficient decreased beyond a certain CR percentage due to reduced natural frequency. On the contrary, incorporating fiber reduced displacement, enhanced the damping ratio and damping coefficient, and maintained time periods comparable to conventional concrete. Moreover, the curvature ductility improved further by incorporating fiber in addition to CR. This study concludes that PP fiber can improve the dynamic performance of rubberized recycled concrete for sustainable structural applications.
The present study investigates the feasibility of using treated recycled concrete aggregate (TRCA) in pavement quality concrete (PQC) to replace coarse stone aggregate (CSA). The PQC mixes were evaluated at five TRCA replacement levels of 0%, 25%, 50%, 75%, and 100% for their mechanical strength and durability. Results showed an improvement of 33.3% and 30% in terms of flexural strength in M40 and M50 grades, respectively, at 90 days of curing when TRCA replaced CSA completely. The cost of construction was reduced by 28.60% and 24.70% in M40 and M50 grades of PQC, respectively, with the use of 100% TRCA. Machine learning models were used to predict the flexural strength, and the support vector regression model achieved the highest accuracy with the highest R 2 value, and the lowest root mean square error. Overall, the use of TRCA provides a cost-effective and high-performance alternative for pavement construction for sustainable goals.
Active transportation modes such as cycling and walking play a critical role in contemporary transportation systems by offering a healthy and environmentally friendly alternative to motorized travel. As both cyclists and pedestrians are among the most vulnerable roadway users, prioritizing their safety is paramount. Most initiatives and research on accommodating these vulnerable road users (VRUs) have focused on urban intersections, with less guidance being available for interchange ramps, which are high-speed, free-flow environments, typically with uncontrolled conflict points that pose distinct risks to VRUs. This study demonstrates tools, processes, and methodologies that have the potential to evaluate interchange alternatives to help give clearer guidance for safely accommodating VRUs through interchange environments. Microsimulation, a design flag assessment, and a safe systems index methodology are identified, and are demonstrated with Ontario, Canada, case studies, as tools capable of facilitating the safe accommodation of VRUs at interchanges.
