| dc.description.abstract | The traditional Friction Pendulum System (FPS) isolator has an isolation period similar to near-field earthquakes, making it prone to resonance. However, the Sliding Isolators with Variable Curvature (SIVC) can address this drawback. The isolation period of SIVC varies with displacement and can be divided into two stages: the softening stage, where the bearing stiffness decreases with increasing displacement, reducing the structure′s acceleration response; and the hardening stage, where the bearing stiffness increases with increasing displacement, thereby reducing the structure′s displacement response. This effect can effectively reduce the occurrence of resonance and further decrease the displacement of the bridge deck. Previous studies have confirmed that the Polynomial Friction Pendulum Isolator (PFPI) with a polynomial friction pendulum of sixth-order equation in the SIVC can fully exhibit its isolation effect when applied to straight bridges of equal or unequal height, performing well under both near-field and far-field seismic waves.
However, there have been few cases in the literature using PFPI for curved bridges. This study extends previous research on horizontally curved girder bridges. In the numerical analysis, an Implicit Dynamic Analysis Procedure based on Equivalent Nodal Secant Properties (IDAP-ENSP) was used to compare the dynamic behavior of single-span and multi-span curved bridges with PFPI under various conditions. The parameters varied included curvature, different support configurations, and seismic wave input angles. Multiple sets of different seismic waves were analyzed, and the results were compared with those where PFPI supports were replaced by FPS. The research data showed that as the radius of curvature of the girder decreased and the seismic wave input angle increased, the difference in bearing reaction forces and internal forces of the girders increased, and different configurations also resulted in varying mechanical behaviors. In the comparison between the two types of supports, while the bearing reaction force of the PFPI isolator was greater than that of the FPS, the displacement of the PFPI isolator was significantly smaller than that of the FPS, proving that the PFPI exhibits good isolation performance in horizontally curved girder bridges.
Moreover, to better simulate real conditions, this study also used real bi-directional seismic wave data for analysis. The results indicated that, apart from the input angle of the seismic wave having an inconspicuous effect, the behavior was similar to that of the unidirectional seismic wave analysis. For the plastic hinge behavior at the base of the pier columns, the Takeda model was used for simulation. It was observed that the impact mainly occurred in the internal forces of the girders. With the addition of the Takeda model, the internal forces of the single-span girders decreased, while the internal forces of the multi-span sections increased. | en_US |