Search

Abstract This paper presents a probability-based method, based on the design required separation length, to evaluate the likelihood beyond the required separation length of pounding of bridge structures under seismic excitations. Firstly, based on the stochastic vibration theory, the probabilistic pounding model was developed to model the influence of different seismic intensity levels and local soil condition on determination of the required separation gap between bridge segments. Then, the varying relationship between exceedance probability of pounding and seismic intensity measure (PGA) was derived. The proposed probability-based pounding evaluation approach was applied to a real bridge for predicting the pounding occurrence under various seismic intensity levels, along with the finite element model of the bridge pounding system built in ANSYS. Finally the pounding risk assessment beyond the required separation length of the bridge structure was conducted and presented based on the required separation distance. The results of this study delivered explicit and direct specifications and guidelines for seismic pounding design of bridges with different separation gap. Highlights • A probability-based method is proposed to evaluate the likelihood of  pounding of bridge structures under seismic excitations. • The probabilistic method can predict whether the pounding occur at different seismic intensity levels in newly built and existing bridges. • The relationship between conditional exceeding probability of pounding beyond the design required separation distance and seismic intensity measure (PGA) is derived. • Recommendations for actual seismic pounding design of bridges with different separation gap are drawn. [ABSTRACT FROM AUTHOR]

This paper proposes an improved high precision direct integration method (I-HPDIM) and an absolute-response-oriented scheme of pseudo-excitation method (PEM) for nonstationary stochastic seismic analysis of large structures under tridirectional nonuniformly modulated spatial ground motions. The proposed approaches resolve the bottle-neck problem of conventional HPDIM and significantly improve computational efficiency of both PEM and HPDIM, making the proposed nonstationary stochastic analysis scheme more attractive for engineering purposes. Hence, it has been implemented in general finite element platforms, having powerful and versatile modelling and analysis capabilities, for stochastic seismic analysis of large and complex structures under tridirectional nonstationary spatial seismic motions. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a theoretical nonstationary stochastic analysis scheme using pseudo-excitation method (PEM) for seismic analysis of long-span structures under tridirectional spatially varying ground motions, based on which the local site effects on structural seismic response are studied for a high-pier railway bridge. An absolute-response-oriented scheme of PEM in nonstationary stochastic analysis of structure under tridirectional spatial seismic motions, in conjunction with the derived mathematical scheme in modeling tridirectional nonstationary spatially correlated ground motions, is proposed to resolve the drawbacks of conventional indirect approach. To apply the proposed theoretical approach readily in stochastic seismic analysis of complex and significant structures, this scheme is implemented and verified in a general finite element platform, and is then applied to a high-pier railway bridge under spatially varying ground motions considering the local site effect and the effect of ground motion nonstationarity. Conclusions are drawn and can be applied in the actual seismic design and analysis of high-pier railway bridges under tridirectional nonstationary multiple excitations. [Copyright &y& Elsevier]

• The seismic responses of long-span and asymmetrical suspension bridges subjected to near-fault ground motions are investigated systematically and comparatively. • The influence of velocity pulse effect, site effect, and structure-soil interaction on the seismic responses of interests in the suspension bridge seismic analysis is considered and analyzed. • Recommendations for the seismic design of long-span and asymmetrical suspension bridges subjected to near-fault ground motions. The objective of this paper is to investigate the seismic responses of long-span and asymmetrical suspension bridges subjected to four intensity level (Small, moderate, huge, and super earthquakes) of near-fault ground motions. A typical suspension bridge located in Yunnan province of China is selected herein to study the dynamic response of long-span and asymmetrical suspension bridges. And the corresponding finite element model based on the platform of OpenSEES is established to consider the influence of velocity pulse effect, site effect, and structure-soil interaction on the seismic responses of interests e.g., tower, girder, and pile, etc., in the suspension bridge seismic analysis. Besides the near-field and far-field ground motion records are employed from the data base in Pacific Earthquake Engineering Research Center of the United States for comparison analysis. Finally numerical analysis results have suggested that the influence of near-fault effect on the response of long-span and asymmetrical suspension bridges and the different dissipation capacity of nonlinear viscous damper in various intensity levels should be paid more attention to in the seismic design of this type bridges. [ABSTRACT FROM AUTHOR]

Abstract Anchored stabilizing pile is a typical earthquake-resistant structure in reinforced slope with advantages of safety, reliability and low cost. It demonstrated excellent seismic performance during the 2008 Great Wenchuan earthquake. However, due to the complexity of the structural system, the coupling relationship between soil, pile, and anchor cable is not well understood at present. This paper developed an analytical model in modeling the dynamic responses of the pile, anchor cable and soil slope system based on Winkler elastic foundation beam theory. The seismic design of the anchored sheet pile wall can then be carried out. An experimental shake-table test was conducted to validate the proposed analytical model. Through the test, the displacements of the pile, axial force of the anchor cable, and earth pressure along the pile derived from the analytical model were validated by the test results. It shows that the proposed analytical model is suitable for the practical application and can provide theoretical basis for dynamic response analysis and seismic design of anchored sheet pile wall. Highlights • An analytical model of anchored sheet pile wall under ground motion is derived. • Analytical solutions of dynamic interaction between pile, anchor cable and slope can be obtained. • Seismic design of anchored sheet pile wall can be carried out through the analytical model. • The accuracy and reliability of the proposed analytical model are validated by the shake-table test. [ABSTRACT FROM AUTHOR]