Recycled aggregate concrete-filled square steel tube (S-RACFST) frame has the characteristics of high bearing capacity, good ductility, and superior seismic performance. To propose a displacement-based seismic design of S-RACFST frame, the validity of the design method was verified by a detailed calculation example. Based on the performance requirements, this design method divided the structural performance into five levels: normal use, temporary use, use after strengthening, life safety, and collapse prevention, and suggested specific steps for the displacement-based seismic design of S-RACFST frame using the inter-story displacement angle limit value as the quantitative indicator. The 10-story S-RACFST frame was used as an analytical example for static elasticplastic analysis. The pushover lateral displacement curves of the frame structure at each performance level were obtained and compared with the displacement-based seismic design curves. The results show that the displacement-based seismic design method of S-RACFST frame structures can fulfill the performance level requirements such as "temporary use," "normal use," and "collapse prevention," and the displacement-based seismic design method is one of the effective ways to realize the performance design of S-RACFST frame structures.
The self-assembled multilayers have been studied by many researchers to modify the surfaces of artificial implants for increasing biocompatibility. The accurate mechanical properties of the film can only be obtained from the experimental results using appropriate theoretical models. As the film is composed of both solid polymers and fluid, this paper proposes a two-phase model. Based on the volume average method, the momentum equations are derived for both solid and liquid phases. In order to test our model, we built the porous film on the gold chip of the quartz crystal microbalance using the layer-by-layer method. The buildup process is based on the electrostatic interactions between anionic sodium hyaluronate and cationic chitosan by imitating the endothelial surface layer. By fitting our model to the experimental changes of the resonant frequency and dissipation factor, we get reasonable values of the film thickness, the porosity, the shear modulus of the solid phase, and the permeability. Compared with the existing models, the newly introduced permeability is an important property of the porous layer affecting the values of other parameters. Our model can provide more intrinsic properties of the selfassembled polymeric network and explain its interaction with the permeating fluid. Published by AIP Publishing. [http://dx
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