The study, “Assessing and Improving the Vibration and Fatigue Performance of Aluminum Pedestrian Bridges,” will include vibration tests on aluminum pedestrian bridges in the field and on a full-scale bridge specimen in the laboratory. These tests will be used to validate finite-element models of aluminum pedestrian bridges and biomechanical models for simulating pedestrian loading. Data acquired from the tests will be used to assess the vibration performance and fatigue behavior of aluminum pedestrian bridges subjected to pedestrian and crowd loading and to enable development of vibration dampening guidelines for aluminum pedestrian bridges.
The full-scale bridge specimen will be instrumented with triple-axis load cells at the bridge’s four supports, strain gauges at key locations to measure strains, and accelerometers to measure the bridge’s acceleration responses. Additional fatigue tests will be conducted on individual bridge joints under variable amplitude loading conditions that are typical for aluminum pedestrian bridges. Strains at the hot-spots on these cast/bolted tripod node joints will be measured, and fatigue results analyzed.
“MAADI Group is providing us with an in-kind MakeABridge weld-free all-aluminum structure for this load study because it is very easy to extend and adjust the bridge’s length, compared to a welded bridge,” said Professor Walbridge, “The footbridge span, deck weight, boundary conditions, and loading characteristics will be varied to generate data under dynamic conditions. Laboratory tests will include strain measurements from single and multiple pedestrians walking, running and jumping. Accelerations and longitudinal, vertical, and lateral forces at all supports will be measured and used to develop and validate analytical models. Data from these load tests will help engineers to design optimal vibration-alleviating solutions and more cost-effective, longer span aluminum pedestrian bridges.”
Professor Walbridge is a member of the Technical Committee for the Canadian Highway Bridge Design Code, Chapter 17, Aluminum Structures. He conducts research in the area of fatigue assessment and strengthening of metal structures. Professor Narasimhan has conducted extensive analytical and experimental research on vibration behavior of structures retrofitted with passive and active damping systems, focused on understanding the behavior of linear and non-linear structures and control devices, and the processing of measurement data from vibrating structures to assess their condition. The study is co-sponsored by the Aluminium Association of Canada (AAC) and the Natural Sciences and Engineering Research Council of Canada (NSERC).
MAADI Group president and CEO Alex de la Chevrotière said, “This load study will enable civil engineers to design footbridges that better withstand crowd loading and strains caused by heavy pedestrian use. The Make-A-Bridge modular system allows removal of bridge sections and can be rapidly constructed and deconstructed in order to test and assess various spans and geometries using a single structure. We’re pleased to be the go-to resource for this study’s test structure.”
As stated in AASHTO (Guide Specifications for Design of Pedestrian Bridges): “The potential for significant response due to dynamic action of walking or running has been recognized by several analyses of problem bridges and is provided for in other design codes… Research into this phenomenon has resulted in the conclusion that, in addition to stiffness, damping and mass are key considerations in the dynamic response of a pedestrian bridge to ensure acceptable design.”
MAADI Group engineers focus on the structural and economic advantages of designing bridges with cast and extruded aluminum components, creating pedestrian bridges and marine structures that are durable, recyclable and offer a maintenance-free lifespan.