Abstract:Based on the design principle of "strong transformation", a multi-lines defense seismic fortification method has been proposed for the frames with prestressed steel reinforced concrete (PSRC) vierendeel truss transfer story. In this method,the transfers columns and lower chord of transfer truss are designed as the last defense line. The second line includes the frame columns joined with transfer story, the upper chord and the middle web members of the transfer truss. Finally, the other columns and beams upon transfer story are the first line. In this study, firstly, the OpenSEES software was used to set up a series finite element models. Then the elastic-plastic time history analysis was finished under the horizontal and vertical earthquakes to study the basic seismic performance and the influence of the difference vertical motion (V/H=0, 0.65, 1.2). Results show that the structure can avoid the overall and partial damage under rare and very rare earthquake level (V/H=0.65). And a "beam-column mixed hinge mechanism" can be formed to dissipate energy mainly relying on the beams upon transfer story. The target of multi-lines defense seismic fortification has been realized. On the other hand, with the increase of the vertical component of the ground motion, its influence is focus on the increase of the lower chord deflection.