\r\nnonlinear dynamic analysis of seismically base-isolated structures, a

\r\nMixed Explicit-Implicit time integration Method (MEIM) has been

\r\nproposed. Adopting the explicit conditionally stable central

\r\ndifference method to compute the nonlinear response of the base

\r\nisolation system, and the implicit unconditionally stable Newmark’s

\r\nconstant average acceleration method to determine the superstructure

\r\nlinear response, the proposed MEIM, which is conditionally stable

\r\ndue to the use of the central difference method, allows to avoid the

\r\niterative procedure generally required by conventional monolithic

\r\nsolution approaches within each time step of the analysis. The main

\r\naim of this paper is to investigate the stability and computational

\r\nefficiency of the MEIM when employed to perform the nonlinear

\r\ntime history analysis of base-isolated structures with sliding bearings.

\r\nIndeed, in this case, the critical time step could become smaller than

\r\nthe one used to define accurately the earthquake excitation due to the

\r\nvery high initial stiffness values of such devices. The numerical

\r\nresults obtained from nonlinear dynamic analyses of a base-isolated

\r\nstructure with a friction pendulum bearing system, performed by

\r\nusing the proposed MEIM, are compared to those obtained adopting a

\r\nconventional monolithic solution approach, i.e. the implicit

\r\nunconditionally stable Newmark’s constant acceleration method

\r\nemployed in conjunction with the iterative pseudo-force procedure.

\r\nAccording to the numerical results, in the presented numerical

\r\napplication, the MEIM does not have stability problems being the

\r\ncritical time step larger than the ground acceleration one despite of

\r\nthe high initial stiffness of the friction pendulum bearings. In

\r\naddition, compared to the conventional monolithic solution approach,

\r\nthe proposed algorithm preserves its computational efficiency even

\r\nwhen it is adopted to perform the nonlinear dynamic analysis using a

\r\nsmaller time step.", "references": null, "publisher": "World Academy of Science, Engineering and Technology", "index": "International Science Index 122, 2017" }