Large Catenary Research Articles

Dynamically substructured testing of railway pantograph/catenary systems

This paper presents a methodology for testing railway pantograph/catenary systems based upon the dynamically substructured system approach for combined physical and numerical components, originally developed by Stoten and Hyde. The main advantage of the dynamically substructured system is that it can provide more stable substructured testing than alternative schemes, such as the commonly used hybrid simulation method, often referred to as hardware-in-the-loop simulation. The developed method is validated through experiments using a simple pantograph rig, together with a numerical simulation of the catenary. In order to realise a real-time simulation of the large catenary model, for the first time in dynamically substructured system testing this study uses (i) a modal analysis technique to reduce the dimension of the contact wire model and (ii) a moving window approach to represent long-distance travel of the pantograph. Finally, the experimental dynamically substructured system test results are compared with simulations of the benchmark pantograph/catenary emulated system.

Experimental investigation of progressive collapse potential of ordinary and special moment-resisting reinforced concrete frames

Two one-quarter-scaled, single-story, two-bay by one-bay, reinforced concrete (RC) building frame models—one each for ordinary and special moment-resisting frames (OMRF and SMRF) conforming to ACI 318 Building Code Requirements for Structural Concrete and Commentary—were tested for progressive collapse, with the objective of studying the difference in the response of the two schemes of reinforcement detailing. The load was applied at 100 mm/s on the failed middle column with 50 mm incremental vertical displacement in each loading cycle. The tests help to develop a better understanding of how connections in the floor systems perform when subjected to large deformations, as well as large catenary and membrane forces. The mechanical behavior of the models has been discussed and analyzed using a simplified model that may be used for the assessment of progressive collapse potential of RC building frames by incorporating the catenary mechanism. The collapse load for OMRF and SMRF models estimated by plastic mechanism was 62.8 and 75.5% of the tested failure capacity, respectively. The special reinforcement detailing of RC building frames (as done in SMRF) is found to help considerably in mitigation of the progressive collapse of building frames.

Collapse Behavior of Steel Special Moment Resisting Frame Connections

There is a common perception that seismic detailing can improve the collapse resistance of steel frame buildings. However, the effect on connection performance of the potentially large catenary, i.e., tensile, forces that can develop during collapse has not yet been adequately studied. The objective of this paper is to use computational structural simulation to investigate a number of key design variables that influence formation of catenary action in steel special moment resisting frame subassemblages. The numerical model used in the study employs a calibrated micromechanical fracture model and is validated using existing test data. The simulation results demonstrate the ductility of seismically designed special moment frame connections and their ability to deform in catenary mode. It is shown that connection ductility and strength are adversely influenced by an increase in beam depth and an increase in the yield to ultimate strength ratio and that the beam web-to-column detail plays an influential role in connection response. A number of conclusions with practical implications are drawn from the numerical results.