Rapid accelerometer measurements of vehicle bumps at bridge approaches

Abstract

Bridge approach settlement (BAS) is one of the most common problems in highway and bridge construction. The settlement can result in unsafe driving conditions, rider discomfort, structural deterioration of bridges, and long-term maintenance costs. BAS research has focused mainly on causes, hazards, and countermeasures, with little emphasis on BAS measurement. This paper presents a rapid vehicle-mounted accelerometer method for BAS measurement and proposes a comprehensive BAS measure consisting of three indexes that measure user physical and psychological comfort as well as the impact on bridge structures. A wavelet transform is used to identify the reaction position. Power spectral density analysis and one-third octave band filtering are applied to calculate the weighted root mean square acceleration as an index of comfort. Adopting the annoyance rate concept from experimental psychology, an annoyance rate model was developed that includes a membership function and the distribution of user comfort levels. A quarter-car model and a linear time invariant (LTI) system were used to estimate the equivalent impact coefficient as an index of durability. Furthermore, a collective system equipped with z-axis accelerometers and a GPS device was created, and small-scale field tests were conducted in Shanghai, China. A velocity correction equation was generated to correct the evaluation model. The test results demonstrate the stability and efficiency of the rapid measurement system.