Seismic performance of single-layer lattice shells with VF-FPB

Friction pendulum bearings (FPB) are recognized as a kind of effective isolation device for protecting and retrofitting an existing structure, but they are not adaptive to different seismic inputs due to the constant friction coefficient and constant radius of curvature. A new isolation bearing called variable-friction friction pendulum bearings (VF-FPB) was proposed which could overcome this limitation while retaining all the advantages of an FPB. Unlike a conventional FPB, the sliding surface of a VF-FPB was divided into several parts with different surface materials which allowed the coefficient of friction to change when the slider went across different parts. This means that the stiffness of a VF-FPB changed as the relative displacement between the slider and the sliding surface changes. In the current paper, the isolation mechanism of a typical VF-FPB was analyzed. The numerical model of a single-layer lattice shell was developed and the effect of VF-FPB installation on the structure was studied. The VF-FPBs used in the study had their surfaces divided into two parts, and it was found that an ‘optimal range’ exists for the dimensions of two component parts for the best earthquake isolation effect. It was concluded that VF-FPBs could improve the seismic performance of a single layer lattice shell more effectively than conventional FPBs.