It is remarkable, meanwhile, that the structural response, hysteretic behavior and energy dissipation of the controlled system can be improved to a desirable performance, which elucidates the validity and applicability of the developed nonlinear stochastic optimal control methodology. The case study shows that the proposed method is feasible to represent the seismic ground motion with only a few random variables. Further, it is pointed out that there exist different descriptions of this principle and, from these different descriptions, combining with the Eulerian or Lagrangian description of the associated dynamical system will lead to different probability density evolution equations. Finally, linear and nonlinear responses of a multi-degree-of-freedom system subjected to random ground motions are carried out to exemplify the effectiveness and advantages of the stochastic harmonic representations. The traditional probability density evolution equations of stochastic systems are usually in high dimensions. Chan and Gang Hu, A study on the profile of the turbulence length scale in the near-neutral atmospheric boundary for sea homogeneous and hilly land inhomogeneous fetches , Journal of Wind Engineering and Industrial Aerodynamics , 10.
These bearings comprise steel tubes with a pressurized internal fluid and attached permanent magnets, and slide over aluminum base plates also with attached permanent magnets. Moreover applicability of the probability density evolution method on engineering problems faces critical difficulties when the system embeds too many random variables. In this method, based on the principle of preservation of probability, a generalized density evolution equation was derived. The results show that the effectiveness of responses control hinges on the physical meanings of the optimal control norms. In the present paper, a new stochastic harmonic function representation by partitioning the wave number domain is proposed. The strain rate effect is considered as viscous effect so that the dynamic generalization of the static model could be developed by analogy with viscous-plastic theory.
Date Issued 2015-07 Description Random field models are widely adopted in engineering practice, for instance, to describe the mechanical properties of an engineering site or a civil structure. The proposed approach is discussed in detail on how to construct the equivalent extreme-value event and then implement the procedure numerically. American University of Armenia Press, Yrevan, Armenia, 2012. This method was developed to analyze the failure process of the extra-long pre-stressed concrete beams. The relationship between the local average of the random field and the random field expression is related to the correlation distance Vanmarcke, 2010. The theoretical developments are properly supplemented by examples from earthquake, wind, and ocean engineering.
In the present paper, a simplified integrated multi-degree-of-freedom model which characterizes the rotation of blades and the aerodynamics of blades is adopted. The approach is based on the recently developed probability density evolution method, which enables the instantaneous probability density functions of the stochastic responses to be captured. In the present paper, a new stochastic harmonic function representation by partitioning the wave number domain is proposed. Proceedings of the 8th International Conference on Structural Safety and Reliability. Stochastic Dynamics of Structures presents a methodology of the effects of both external excitation and a structure's internal properties. The physical stochastic optimal control strategy is extended, and a novel nonlinear optimal control method for randomly excited hysteretic systems is developed, referring to the optimal polynomial control scheme.
Constrains are enforced on the control force to prevent large structural stresses in the floater at specific hot spots with the risk of inducing fatigue damage, or because the demanded control force cannot be supplied by the actuator system due to saturation. Numerical results reveal that a linear control with the 1st-order controller suffices even for the hysteretic structural systems when a control criterion in exceedance probability performance function for designing the weighting matrices is employed. The performance and reliability of engineering structures under extreme disastrous dynamic excitations e. The most widely employed approach to represent a random field is the spectral representation. The associated probability of each point is simultaneously transformed accordingly.
For the dynamic reliability problem, the solution can be derived through solving the probability density evolution equation with an initial value condition and an absorbing boundary condition corresponding to specified failure criterion. The classical method for this is to fit one of the extreme value probability distribution functions to extracted maxima of the response of wind turbine. The popular viewpoint that randomness of structural parameters is trivial compared to that of excitations is overthrown. Readers will gain insight into core concepts such as Stochastic process models for typical dynamic excitations of structures, Stochastic finite element, and random vibration analysis. Fundamentals and numerical algorithms for the synthesized method are described.
A family of performance control policies of stochastic dynamic systems are proposed based on the probability density evolution theory and numerical optimizing strategies in the present paper. Results of a study of about 70 spectra of the horizontal components of gustiness in strong winds are described. Sliding isolation, as one of the modalities of base isolation, has demonstrated its value in seismic hazard mitigation. Case studies demonstrate that coupling of nonlinearity and randomness will greatly change the response characteristics of the structure. Table 1: Geometry of the plate Length Width Thickness10m 10m 0. An original approach for dynamic response and reliability analysis of stochastic structures is proposed. Collected Research Reports on Earthquake Engineering.
Numerical examples are illustrated, showing the fair accuracy and efficiency of the proposed method. In particular, a two-step approach is suggested, and the existence and uniqueness of optimal assigned probabilities are proved. The numerical method for multi-dimensional integrals is of great importance, particularly in the uncertainty quantification of engineering structures. A 1:8 scaled model structure was tested. The popular viewpoint that randomness of structural parameters is trivial compared to that of excitations is overthrown. In the present paper, the new advances of the probability density evolution method and its applications to seismic response and global reliability of structures, as well as the existing approaches, are outlined and reviewed.
He has received a variety of national and provincial-level awards for Advancement in Science and Technology. This equation holds for any response or index of the structure. The authors outline the fundamental concepts of random variables, stochastic process and random field, and orthogonal expansion of random functions. Li and Chen also cover advanced topics, including the theory of and elaborate numerical methods for probability density evolution analysis of Stochastic dynamical systems, reliability-based design, and performance control of structures. Numerical results reveal that the linear control with the 1st-order controller suffices even for the hysteretic systems when an exceedance probability based control criterion for designing the optimal weighting matrices is employed.