Abstract : In non-smooth transient structural dynamics, the choice of the time step and the time integrator has a critical impact on the feasibility of the simulation. For instance, during an earthquake, a bridge crane, usually located overhead in buildings, may be subjected to multiple impacts between crane wheels and rail. These multiple impacts cause significant damage in the structure. Then the qualification of these structures with respect to normative seismic design requirements, which are continuously developing and becoming more and more stringent, requires strengthened simulation techniques especially to model the impact phenomenon. Furthermore, multiple time-scales coexist in a bridge crane under seismic loading. In that case, the use of multi-time scale methods is suitable. Here, we propose a new explicit-implicit heterogeneous asynchronous time integrator (HATI) for non-smooth transient dynamics with possible contacts and impacts. In a first step we introduce a Moreau-based eventcapturing explicit time integrator for contact/impact problems. In a second step, a two time scales explicitimplicit HATI is developed : it consists in using an explicit time integrator with a fine time scale in the contact area, while an implicit time integrator is adopted in the other parts in order to capture the low frequency content of the solution and to optimize the CPU time. 3D Transient dynamics applications illustrate the robustness and the efficiency of the proposed approach.

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