Structures Congress 2013
May 2-4, 2013
Navid Zolghadri; Marvin Halling; Paul Barr; and Steven Petroff
A bridge’s performance depends on different factors including superstructure type, support conditions, construction materials, environmental conditions and external loading. Identifying and evaluating the loads applied to a bridge, during its effective life, are necessary for assessing the condition and remaining life of that bridge. Furthermore, the influence of dynamic loading on the structural response of the bridge is important to be considered for the safety of the structure. Although ambient loads can be helpful to assess the changes in bridge condition as monitored over time, applying identified loads allows for a more clear understanding as to how the bridge responds to different types of loads. As a part of the Long-Term Bridge Performance (LTBP) program, a bridge located in Perry, Utah was subjected to four sets of high speed, live-load tests. For evaluating the bridge response to different types of loads, these live load tests were conducted with four different truck configurations that traversed the bridge in both right and left lanes. In addition, the different trucks traversed the bridge at three different speeds to make it possible to assess the effect of dynamic response of the bridge. Moreover, these different trucks varied in weight and axle spacing. The data were collected through multiple types of sensors, located on different points and some co-located on same points. The sensors used in this study are strain gauges and the response of the co-located sensors was compared to evaluate the reliability of the results. Two different B-WIM methods were used to calculate the speed of the trucks. These methods include the correlation of signals and the derivative of the strains. The performance of these methods for evaluating the accurate speed was studied. The axle distances of the trucks were also calculated through the derivative of the strains. Through these B-WIM algorithms and the long-term monitoring system installed on the bridge, the traffic on the bridge and the bridge dynamic response to the truck loadings can be quantified with very simple and inexpensive calculations.