In order to increase the efficiency of the structures to resist seismic excitation, combinations of inerter, negative stiffness, and tuned mass damper are used. In the present work, the optimum tuning frequency ratio and damping of the tuned mass negative stiffness damper-inerter (TMNSDI) for the base-isolated structure were determined by employing the numerical searching technique under filtered white-noise earthquake excitation and stationary white noise. The energy dissipation index, the absolute acceleration, and the relative displacement of the isolated structure were considered as the optimum parameters, obtained by their maximization. Evaluations of base-isolated structures with and without TMNSDI under non-stationary seismic excitations were investigated. The efficiency of the optimally designed TMNSDI for isolated flexible structures in controlling seismic responses (pulse-type, and real earthquakes) were evaluated in terms of acceleration and displacement. A dynamic system was used for deriving the tuning frequency and tuned mass negative stiffness damper inerter (TMNSDI) for white noise excitation by using explicit formulae of the curve fitting method. The proposed empirical expressions, for design of base-isolated structures with supplementary TMNSDI, showed lesser error. Fragility curve results and story drift ratio indicate reduction in seismic response by 40% and 70% in base-isolated structure using TMNSDI.

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The procedure of estimating the RC moment-resisting frames under blast loading using a multi-mode adaptive pushover (MADP) analysis is investigated in the current study. The main advantage of the proposed procedure is the combination of the multi-mode and adaptive pushover analysis approaches, which has not been done in the past for blast loadings. To investigate the efficiency of the proposed approach, several RC moment-resisting frames (RC-MRFs) of the 4-, 8-, and 20-storey are considered in the study. For a better comparison, the conventional modal pushover analysis (MPA), nonlinear response history analysis (NRHA), and the proposed approach are considered in the simulations. To this end, various influential parameters including the lateral force, floor displacement, storey drift, storey drift ratio, etc. are considered. For all models, the first three mode shapes were considered in the analysis procedure, while for the case of 20 storey RC-MRF, the torsional effect is included as well. The results indicated that the proposed MADP procedure has adequate accuracy and efficiency to estimate the blast loading demand on RC-MRFs.

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