To test the nonlinearity and non-stationarity of measured dynamic signals from a bridge structure with high-level noise and dense modal characteristics, a method that combines the adaptive signal decomposition with the recurrence analysis is proposed to solve the difficulty of testing nonlinearity and non-stationarity of bridge structure signals. A novel white noise assistance and cluster analysis are introduced to the ensemble empirical mode decomposition to alleviate mode-mixing issues and generate single-mode intrinsic mode functions. Combining the hypothesis-testing scheme of nonstationary and nonlinear synchronization and surrogate techniques, a data-driven recurrence quantification analysis method is proposed and a novel recurrence quantification measure pairs are set up. To demonstrate the efficacy of the proposed methodology, complex signals, which are collected from a carefully instrumented model of a cable-stayed bridge, are utilized as the basis for comparing with traditional nonlinear and non-stationary test methods. Results show that the proposed multiscale recurrence method is feasible and effective for applications to a nonlinear and non-stationary test for real complex civil structures.

This paper focuses on the identification of tension in suspenders equipped with supplemental dampers in through and half-through arch bridges. Although the differential equation governing the transverse vibration of beams can be modified to include the restraining actions and energy dissipative features of the damper, ensuing solutions relating suspender tension to suspender frequency can only be expressed implicitly, rendering the approach impractical in real bridge applications. This paper develops a simpler, practical identification method which takes into consideration the influence of the damper. Numerical results relating suspender frequency to suspender tension and damper lateral stiffness can be visualized as a surface plot, which in essence is a signature of the suspender system. Feasibility of the tension identification method is demonstrated using a recently completed 180-m-span bowstring arch bridge. Results are promising because suspender tensions are identified with acceptable accuracy. It is further contended that the proposed method is effective in identifying the tension in suspenders equipped with supplemental dampers at all stages of construction and the process can be readily extended to tension identification during the service life of bridges.