Effect of complex damping on seismic responses of a reticulated dome and shaking table test validation

The dynamic responses of large-span space structures are significantly associated with some higher structural frequency modes. A proper finite element model with accurate modal damping ratios is a key factor in obtaining precise structural seismic responses in numerical analyses. The complex damping model is often used in frequency domain structural analyses because of its characteristics of constant modal damping ratio with frequency and frequency-independent energy dissipation. Based on the five-parameter integer-order derivative method, a user subroutine of ABAQUS is developed to estimate the complex damping model in time-domain dynamic analyses. A shaking table test of a scaled and simplified single-layer reticulated dome is first conducted to validate the user subroutine. Detailed test data, including the identified natural frequencies and modal damping ratios, free vibration curves, and representative maximum responses, are summarized and compared with the corresponding finite element results using the complex damping model and a Rayleigh damping model. The comparisons indicate that the results of the complex damping model can yield a better estimation of the test data. Finally, the effect of the complex damping on the seismic responses of a single-layer reticulated dome is systematically studied by comparing the structural frequency properties and dynamic characteristic responses with those of Rayleigh damping. The results show that the complex damping model provides smaller structural modal damping ratio variation, lower ultimate seismic loading, and severer structural plastic developments.