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Model reduction procedures for the purpose of reducing computational efforts in structural analysis are already well developed and widely used to compute the dynamic response of complex structural systems. For example the Guyan reduction might essentially reduce the size of the structural matrices, while component mode synthesis provides a means to consider first simpler substructures and to use its...
Structural vibrations are often dominated by resonant response, and increased efficiency in the damping of these vibrations can often be attained by using the resonant properties of these modes. A typical example is the ‘tuned mass absorber’. While the original design procedure was based on properties of the frequency response graph, it has recently been demonstrated that the problem can be generalized...
The reliability analysis of nonlinear-hysteretic structures subjected to uncertain earthquake excitations is an important but challenging problem in stochastic structural dynamics and performance-based earthquake engineering. The ‘first passage probability’, i.e., the probability that some response quantities of interest (e.g., interstory drifts) exceed specified threshold levels, is often of concern...
In this work, the spectral characteristics of non-stationary random processes are applied to the time-variant first-passage problem in structural reliability. The first-passage problem consists in computing the probability of a response quantity exceeding a deterministic threshold in a given interval of time when the parameters defining the structural system and/or the loading are random quantities...
Seismic assessment of linear systems is usually performed adopting the well-known modal analysis along with response spectrum technique. Limits of this approach are directly related to the hypothesis of stationary behavior of the response adopted for deriving most common modal combination rules, i.e. SRSS, CQC. Generally, the response of a structure under seismic actions is non-stationary and pertinent...
Dysfunctions and failures of buried pipe networks like sewer networks are studied from the point of view of the heterogeneity of geotechnical conditions in the longitudinal direction and of the applied action (seismic action). Combined soil defects (differential settlements along the pipe, landslides, voids surrounding the pipe, etc.) and peak ground acceleration (PGA) induce stresses (which leads...
This contribution presents a novel approach for solving reliability-based optimization (RBO) problems. In particular, the reliability-based optimization of structural systems under stochastic loading is considered. The approach is based on a descent-feasible direction and a line search strategy, allowing to explore the space of the design variables most efficiently. The proposed method is monotonically...
Realistic modeling of structures depends on both refined FE models and the incorporation of uncertainties inherent to geometric, structural and loading parameters. In this work, a mode-based meta-model is adopted for performing an efficient stochastic dynamic reliability analysis of a multi-story building subjected to stochastic ground acceleration. The meta-model allows for an efficient evaluation...
Current research efforts for the efficient prediction of the dynamic response of structures with parameter uncertainty concentrate on the development of new and the improvement of existing methods. However, they are usually limited to linear elastic analysis considering only monotonic loading. In order to investigate realistic problems of structures subjected to transient seismic actions, a novel...
The design of slender structures subject to wind actions must take into account many sources of uncertainty in the environmental parameters that describe the wind field at the site, in the structural mechanical properties, and in the parameters that influence the interaction phenomena. For the sake of simplicity, three types of uncertainty can be distinguished: (i) aleatory uncertainty, related to...
One of the most widely used techniques for the simulation of Gaussian evolutionary random fields is the spectral representation method. Its key quantity is the power spectrum, which characterizes the random field in terms of frequency content and spatial evolution in a mean square sense. For the simulation of a random physical phenomenon, the power spectrum can be directly obtained from corresponding...
Earthquake-induced ground-motion may be realistically described as random processes that are intrinsically non-stationary in both amplitude and frequency content. In order to take into account the finite duration and the amplitude non-stationarity of earthquake-induced ground-motions, it is common practice to modulate a stationary stochastic process with a shaping window, or envelope function, in...
Computational approaches to systems involving random fields or stochastic processes have to discretise these fields or processes. This produces– when compared to the deterministic case – many variables in the computation, resulting in a very high-dimensional problem. Based on the conviction that the essential stochastic properties of the system are close to some – albeit unknown – lower dimensional...
Slender structures exposed to a strong vertical component of an earthquake excitation are endangered by auto-parametric resonance effect. This non-linear dynamic process in a post-critical regime caused heavy damages or collapses of many towers, bridges and other structures due to earthquake attack in the epicenter area. If an amplitude of a vertical harmonic excitation in a structure foundation...
In this work we discuss the failure analysis of civil engineering structures built of heterogeneous materials. The material heterogeneities call for a detailed representation of typical micro or meso-structure, which can be provided with the structured FE mesh representation as illustrated herein for 2D case and two-phase material. The building-block of such a representation is the constant stress...
Due to their useful properties, metal foams became an interesting, often utilized and investigated material. Recent applications are in areas, where dynamic processes play a significant role. In the huge amount of literature about metal foam, mainly the material properties like strength and stability are investigated but the dynamic behavior is rarely the object of research. Therefore this work investigates...
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