基于RSC体系的双层桥梁排架墩地震损伤控制设计

为实现钢筋混凝土（RC）双层桥梁排架墩的地震损伤控制设计，提出将上层桥墩设计为装配式摇摆-自复位（RSC）结构，下层桥墩设计为装配式承插连接，但不发生摇摆反应的双层桥梁排架墩。给出新型排架墩中无黏结预应力筋、耗能角钢等的设计方法。以甘肃省洛塘河大桥非规则双层排架墩为原型，建立普通RC与新型RSC两种双层排架墩抗震数值分析模型，并结合太平洋地震工程研究中心（PEER）完成的RSC排架墩振动台试验结果验证建模方法的准确性。在此基础上，完成RC与RSC排架墩模型在40条近断层地震动下的动力时程分析，对比分析2种排架墩的抗震性能。研究结果表明：RSC排架墩上层桥墩最大层间位移角略大于普通RC排架墩的上层桥墩最大层间位移角，但RSC排架墩下层桥墩最大层间位移角仅为普通RC排架墩下层桥墩最大层间位移角的47%；RSC排架墩上、下层桥墩层间残余位移角仅为普通RC排架墩上、下层桥墩层间残余位移角的2%左右；RSC排架墩可显著降低下层桥墩的地震剪力需求，无黏结预应力筋应力保持弹性，耗能角钢易屈服耗能但未拉断，验证了所建议的双层桥梁排架墩地震损伤控制设计方法的合理性。

Seismic Damage Control Design for Double-deck Bridge Bents Based on Rocking Self-centering System

To achieve seismic damage control design, a new reinforced concrete (RC)double deck bridge bent was proposed. In this bent,the upper precast piers were designed as rocking self-centering (RSC) structures. The lower precast piers were designed with a socket connection but without rocking behavior. A design method was proposed for the unbonded prestressing tendon and energy dissipation steel angle used in this new double-deck bridge bent. Seismic analysis models for normal RC and new RSC bridge bents were developed based on design details of the irregular double-deck bridge bent of the Luotanghe Bridge in Gansu Province. The accuracy of the modeling technique was verified against shake table test results for a RSC bridge bent conducted by the Pacific Earthquake Engineering Research Center. Then,dynamic time history analysis was conducted for both the RC and RSC bridge bent models under a series of 40 near-fault ground motions. The seismic behaviors of the normal RC and new RSC double-deck bridge bents were obtained and compared.The results show that the maximum story drift ratio of the upper piers in the RSC bent is slightly larger than that in the upper piers of the normal RC bent, whereas the maximum story drift ratio of the lower piers in the RSC bent is only 47% of that in the lower piers of the normal RC bent. The residual story drift ratios of the upper and lower piers in the RSC bent are only 2% of those in the upper and lower piers of the normal RC bent. The seismic shear force demand of the lower pier in the RSC bent is evidently reduced as compared with that in the lower pier of the normal RC bent. The stress of the unbonded prestressing tendon in the RSC bent remains in the elastic region. The steel angles will yield and dissipate seismic energy while no rupture damage is observed. Therefore, the proposed design method can effectively avoid seismic damage to double-deck bridge bents.