RELIABILITY ANALYSIS OF UNCERTAIN HIGH-SPEED RAILWAY BRIDGE MODELS

Abstract eng:
This contribution addresses the dynamic response prediction of railway bridges subjected to high-speed trains with stochastic methods to account for uncertainties in the model parameters. For instance, the natural frequencies of the structure may depend on the environmental temperature or on nonlinear response amplitudes. Although the real energy dissipation mechanism is quite complex, commonly simple mechanical models of bridge damping are used, with parameters chosen by experience. Design guidelines recommend the design engineer to create a computational model that reproduces the worst-case response scenario. This conservative approach is non-economical, and in many cases the parameters are not unambiguously to define when some of the relations that influence the dynamic response significantly are unknown. The presented Monte Carlo simulations on bridge models are based on Latin hypercube and line sampling to provide an overall overview of the structural reliability considering frequency variation, uncertain damping, and structural parameters. In particular, acceleration amplitudes and serviceability limits of deformations define the limit states of the bridge models. With variation of the natural frequencies and bridge damping, both resonance speeds and the magnitudes of the resonance peaks are uncertain. The outcomes of the stochastic numerical models with different degree of sophistication are compared with results of deterministic computations defined in design guidelines.

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