Applied Mechanics and Materials Vols. 204-208

Abstract: As to improve bridges’ seismic performance, horizontal earthquake was isolated at the bottom of piers. With one pier system as the object of study, adopting nonlinear time history analysis analyzed the un-isolation system, the traditional isolation system and the new isolation system’s seismic performance especially when the actual earthquake was different from the design earthquake, in which the new isolation system was based on rolling balls. Results shows, as for the new isolation system, the internal force is independent of earthquake accelerations and earthquake periods, therefore, sympathetic vibration will not exist, and the internal force is always too small to destroy the system.

Abstract: Energy dissipation reduction design can achieve the performance-based seismic design. By contrasting the results of the frame with the SMA dampers and the original structure, the results prove that the SMA damper can reduce the seismic response effectively and achieve the important performance objective “no damage under moderate earthquake and maintainable under major earthquake”.

Abstract: Analysis of Probability has been applied to evaluate the vulnerability of buildings and other facilities under the effect of earthquakes in USA and other countries. During the past ten years, this method becomes an efficient method to evaluate the seismic capacity of structure in many serious earthquakes, such as Northridge Earthquake of 1994 and so on. However, probability and Statistics of Vulnerability has not been attached enough importance it deserves in the evaluation of performance of seismic capacity of structure. The vulnerability of reinforcement concrete (RC) frame with regard to recent Chinese earthquake is analyzed by using probability and statistics method. The important risk issue of seismic capacity of formal RC structure is examined, which can serve as a basis for improvements in structural code development.

Abstract: Typically, temporary soil nailing systems are not required to provide for design level earthquake occurrences consistent with the building or structure being constructed inside the excavation. However, the seismic response of the permanent soil nail walls during the earthquakes should be evaluated. On the other hand, evaluation of 3D response of soil nailing walls have some strange manners that should be considered in the numerical analysis. In this paper, numerical simulations of soil nail walls under vibrational input have been carried out, and the results are compared with the function of soil nail walls under ordinary statistical loading. The behaviour of geometry of nails are mentioned under static and seismic analysis. After that some investigations are carried out to find respond of soil nailing walls in some 3D excavation forms. The analysis is performed with finite difference software called FLAC3D. The results are prepared as lateral displacement of the walls and normalized maximum tensile forces for nails. These results can demonstrate the behavior of external and internal resistance of soil nail walls under seismic and static analysis. The deformation of wall under the static and dynamic manner varies in a wide range. On the other hand, tensile loads that are produced in nails under the static manner are namely 50% less than the dynamic manner.

Abstract: In the present paper we analyze an innovative strategy for the retrofitting of a Reinforced Concrete (RC) building by the use of hysteretic dissipators. A device called Buckling Restrained Axial Damper (BRAD) is adopted which is used in series with a steel element to form the diagonal braces of the retrofitted structure. Such devices allow a significant improvement of the seismic behavior of the building by providing a better dissipation of the seismic input energy in the structure and thus ensuring a better performance of the RC structure in the elastoplastic range. In the paper the behavior of such devices is described and analyzed in detail. The advantages and disadvantages of their use in the retrofitting of RC structures is discussed. A nonlinear analysis is finally presented for the retrofitting of a RC existing building by a displacement based approach in order to verify the compatibility condition between the displacement capacity of the structure and the displacement demand according to the seismic codes. The performances of the use of the BRAD devices in the retrofitting of RC buildings is thus illustrated in detail.

Abstract: The stationary responses process of single-degree-of-freedom structural system is a stationary process with Markov property in displacement-speed space when the random earthquake load is simulated as flat noise or nearly flat noise. In this paper, the seismic reliability of singe-degree-of-freedom structural system of which the structural responses is with Markov property is studied according to first excursion mechanism. The explicit solution method of the structural seismic reliability is deduced. It is shown from the example that the method of this paper is correct. For the seismic reliability analysis of multiple-degree-of-freedom system, the mode-superposition method can be adopted to transform multiple-degree-of-freedom system into a series of generalized single-degree-of-freedom systems, so the method of this paper is also applicable in the theory.

Abstract: Based on the wedge stability analysis method specified in Design Specification for Concrete Dams (DL5108-1999, in Chinese), the limit state equation applied to deep-seated sliding stability under the earthquake has been deduced, and the safety factor of limit state to quantitatively assess the deep slide of gravity dams has been established. The computation for the project shows that the limit state equation is accurate and applicable.

Abstract: Earthquake is one of the most important external factors causes landslide, the geological and topographical conditions of the slope itself is the most important internal factors which induce landslide on landslide’s size and probability. These factors can be described as background factors impact the seismic landslides. Through the analysis and statistics on seismic landslides’ data in this paper, five directions were studied. These are lithology, slope height, slope angel, slope shape and slope direction. The influence features on number, area and volume of the five background factors show the contribution rate and risk degree. Using fuzzy theory to carry out quantitative and semi-quantitative analysis on these factors, the weights of the five background factors can be determined. Then using the risk evaluation on a specific landslide according to the principle of maximum membership, the result shows this method is reasonable.

Abstract: A test on a full-scale model of a three-spans and two-story steel moment frame with dampers and releasable slab was conducted. The details of the test frames, test instruments, set-up procedures, and test procedures were presented. The column and beam were connected by dampers that could initiate the plastic deformation during cyclic loading before damage occurred in the beam and column. The precast concrete slab was designed to be releasable and for saving story height. The primary objective of this test was to verify structural performance and constructability of a full-scale sustainable steel frame. Test results confirm that the sustainable frame showed stable hysteretic behavior without any serious damage up to a drift angle of 1/12; and the sustainable frames were released systematically in spite of serious cyclic loading.

Abstract: In this paper, the amplification to structural non-linear displacement response caused by near-fault vertical ground motions is investigated quantitatively. Based on a set of 30 acceleration records of near-fault ground motions, two typical concrete frame structures, as numerical examples, are examined by means of nonlinear dynamic time-history analysis at two different stages: (1) through the application of horizontal components of acceleration records, (2) through application of the combined horizontal and vertical components at the same time. The numerical results show that the maximum floor-displacements of two concrete frames are limitedly amplified by the vertical effect of near-fault ground motion. On the other side, the maximum inter-story drifts are amplified obviously, and the magnification caused by the vertical effect is about 15%~20% on average. Hence it is evident that the amplification of near-fault vertical effect on horizontal deformation response could not be neglected, and worth serious consideration in future seismic design and evaluation.