Free vibration tests of a scale model of the South Rangitikei Railway Bridge

The careful design and construction of a scale model of the South Rangitikei Railway Bridge (SRRB) are reported herein. The model was designed in accordance with stringent similitude requirements and a series of dynamic tests including shake table tests were conducted. This paper presents the preliminary results of the snap back tests only. It was not intended to exactly emulate to the actual SRRB but merely to use the SRRB as a realistic existing example, to investigate the general dynamic behaviour of a rocking structure. Despite this, the snap back tests revealed that the scale model matched previously published natural period of the SRRB prior to pier uplift. Furthermore, experimental results suggest the natural rocking period of the prototype SRRB could vary between 1.73 s and 4.33 s depending on the amplitude of lateral displacement. This reaffirms previous research which hinted the natural rocking period of a rocking structure is amplitude dependent and is a non stationary value.