Dynamic Tests for Assessment of Pedestrian Comfort for Design of a Stayed Highway Bridge

Assessment of the performance of a road bridge for pedestrian comfort at design stage is often carried out following simplified rules defined by design codes of practice. The purpose of this paper is to assess the effectiveness of one such simplified procedure by means of actual dynamic load tests carried out on an unconventional cable-stayed bridge with precast pre-stressed deck and solid section 47 mm diameter steel bars acting as tension members in lieu of specific traditional strand cable systems. The rule given by the Spanish Design Code (IAP-11, “Instrucción sobre las acciones a considerar en el proyecto de puentes de carretera”, 2011) is taken as the basic design requirement to be assessed by a series of time records of the vertical acceleration caused by passage of the control vehicle. The tests consisted on recording vertical component of accelerations at the mid-span section where the stays converge just outside of the pedestrian sidewalk. The control or reference vehicle used for the tests conforms to the requirements described in the Spanish IAP-11 Code. The focus of the paper is to establish a direct comparison between the code-prescribed analyses of the structure under the reference vehicle to evaluate pedestrian comfort according to IAP-11. Computed maximum accelerations at the mid-span section are found to be approximately one half of the measured values, fact that is at least partially attributed to ignoring the inertial mass and mechanical characteristics of the reference truck that does not allow for vehicle-structure interaction.