Sensitivity analysis of the lateral damping of bridges for low levels of vibration

Damping is a dynamic property that has not been fully understood. In particular, damping in bridges requires further study in order to gain a better understanding of the parameters that define its value and variation. In practice a constant ratio of 5% of the critical damping is commonly used in seismic analysis and design. However, this may not be accurate for different levels of shaking. In addition, the experimental methods to estimate damping can provide different damping ratios for the same structure, which increases the uncertainties on the damping estimates. This paper presents a sensitivity analysis of the damping in bridges for different types of excitation and low levels of vibration. Data collected from different sources is used to conduct the assessment, namely, scaled model tests, ambient vibration tests, and seismic ground motions from instrumented bridges in California. A discussion of the results using several frequency and time domain methods for damping estimation is presented. © The Society for Experimental Mechanics Inc. 2013.