Advanced Materials Research Vols. 594-597

Abstract: A theoretical analyzing approach about a class of seismic isolation system RFPS (Rolling Friction Pendulum System) is presented.. It starts from the Lagrange equation in multiply body dynamics. This system consists of a roller which is placed in the vicinity of two ellipse concave slides. Computation results for ellipse slide show that it has the three kinds of necessary functions required for an effective isolation system. The relatively long vibration period provides the necessary isolation capability, the gravity provides the reposition capability, and the friction couple, formed with the rolling friction forces at the contacting surface on the top and bottom plate respectively, provides the energy dissipation capability. The evaluation results for a practical building model shows that RFPS has a satisfactory seismic isolation effect.

Abstract: A hydropower plant is usually the major electricity supplier in the region, the failure of underground powerhouse in an earthquake may cause not only the damage to itself, but also secondary disasters to the region in a way of an electricity outage. Seismic stability of these underground complexes is required to be seriously addressed. The underground cavern complex of the Baihetan hydropower plant in Yunnan Province, China, is currently the world's largest underground rock cavern group under construction. Aseismic issues of the underground cavern complex are discussed in this paper. On the basis of this research, seismic variables of the Baihetan project are firstly determined for Design Basis Earthquake and Safety Evaluation Earthquake. The artificial seismic motions for the dynamic analyses are simulated. Two alternative scheme of layout plans of the underground cavern complex are studied, with full 3-D elasto-plastic dynamic response analyses based on the parameters given by the cyclic dynamic loading tests with medium strain rate. The seismic response of seismic displacement and failure zones of each scheme are studied, respectively. A performance verification of the supporting measures during earthquake is also discussed. The results indicate that in spite a wider powerhouse cavern, the scheme "A" which involves a gallery-shaped surge chamber is more stabilized during an earthquake than the scheme "B" whom with barrel-shaped surge chambers. The underground cavern complex with scheme "B" is relatively stable under Design Basis Earthquake and Safety Evaluation Earthquake, despite a minor damage of the surrounding rock. And the implementation of the proposed support system may further guaranteed a safe state of the underground cavern complex in earthquake events.

Abstract: The main bridge of Guangdong jinma which is double cable planes concrete single tower cable-stayed bridge and T- rigid frame cooperative system,and causing great concern to the project owing to the practice successfully[1,2,3,4].This paper analysis Jinma Bridge with response spectrum method of seismic response in accordance with the objectives of the three standards of seismic resistance requirements .In order to ensure the calculation accuracy,before the previous 120 vibration mode superposition should be taken by adopting CQC（Complete Quadratic Combination）method in calculation of the response spectrum.

Abstract: Quasi-static analysis of in-situ reinforced concrete frame joints is done by using finite element software ADINA. The calculation results of the ordinary beam-column joints and the surrounding floor located Corner joints are compared. It is shown that near the beam ribbed slab reinforcement stress significantly increases with the loading displacement increasing, indicating that the floor enhance the flexural capacity of beam. On the conditions of no influence the joint strength, floor set corner can be partially weakened the capacity of the beam flexural, and reinforcement of beams yield significantly in advance. When the beam reinforcement yield, the column of concrete cracks have also been reduced. Meanwhile, the beam-end and column-end plastic hinge appears increase the time interval, so that the joints are closer to the characteristics of the beam hinge mechanisms by the earthquake damage.

Abstract: In the present paper we have analyzed a multi-storey reinforced concrete (RC) building in presence of a hybrid seismic protection system for highlighting the limits of the conventional fixed base seismic design of structures. This hybrid seismic protection system is a passive structural control system that combines the Base Isolation System (BIS) and the Passive Supplemental Damping (PSD). The Viscous Dampers (VS) and Friction Sliders (FS) are the devices adopted in parallel for realizing the innovative base isolation system. The fixed base structure and the base isolated structure have been designed and verified according to the European seismic code EC8 and the European code for the design of concrete structures EC2. A three-dimensional dynamic nonlinear analysis for a base isolated structure has been performed adopting recorded accelerograms for the defined bi-directional ground motions according to the conditions imposed by EC8. The seismic isolation is a promising alternative for the earthquake resistant design of buildings and its peculiarity is that the base isolated buildings are designed such that the superstructure remains elastic and the nonlinearities are localized at the isolation level. In this paper a comparative analysis is presented between the base isolated structure, with the viscous dampers in parallel with friction sliders, and the traditional fixed-base structure.

Abstract: In order to study the parameters influence on seismic behavior of concrete filled steel tubular (CFST) frame with bucking-restrained brace (BRB), the finite element analysis for CFST frame with BRB is studied in this paper, which is performed under low cyclic loading using the software of ABAQUS. Failure model and skeleton curve are comparative analyzed with the related experiment components, verifying that the finite element simulation of the CFST frame with BRB is effective. By changing the axial compression ratio of the column(n) and the steel ratio(α) of the column section respectively, the effect of the structural parameters on the seismic behavior of the CFST frames with BRB had been studied. The results shows that: with the increase of steel ratio of the column section, the lateral ultimate strength and the initial stiffness of the frame get higher, the lateral load(P) versus lateral displacement (Δ) hysteresis curves of the frame get plumper, and the energy dissipation of BRB remain basically unchanged; With the increase of axial compression ratio of the column, the lateral ultimate strength and the hysteretic behavior of the frame become low, whilst the energy dissipated by the BRB get higher.

Abstract: In the present paper the dynamic nonlinear analysis for a 3D base isolated structure is illustrated. A base isolated reinforced concrete building is designed and verified according to the European seismic codes such that the superstructure remains almost completely elastic and the nonlinear elements are localized only in the base isolation system. Nonlinear hysteretic models have been adopted to reproduce the cyclic behavior of the isolators. Two different base isolation systems are considered and their performances are compared for evaluating the behaviour of a base isolated building, highly irregular in plan, in presence of a seismic excitation defined with recorded accelerograms which characterize the bi-directional ground motions. The isolation system has been realized with a combination in parallel of elastomeric bearings and sliding devices. In the first analyzed isolation system we have used the High Damping Rubber Bearings (HDRB) and in the second analyzed isolation system we have used the Lead Rubber Bearings (LRB). Finally a comparative analysis between the base isolated structure with hybrid base isolation systems and the conventional fixed base structure is detailed.

Abstract: The displacement response of special-shaped column frame structure on the elasto-plastic state was obtained with the Pushover method. Using Park-Ang model to calculate the damage level of each floor, and then using the improved mean response spectrum analysis method to compute the mean square response of the maximum elasto-plastic structure interlayer displacement and the probability of different damage levels. The result shows that the seismic performance of special-shaped column structure will be better reflected when the structure is analyzed with the methods mentioned above and these methods have some theoretical significance.

Abstract: By using the DSD-160 dynamic triaxial apparatus, liquefaction experiments under random seismic loading of the saturation original samples from a passenger rail line which located in the loess tableland in china was tested. Based on the test results, connected with the forecasting method of the liquefaction test under random seismic loading and the results of seismic hazard analysis, the liquefaction potential of the saturation loess from different regions in the passenger rail line is distinguished. Moreover, the predictions include 50 years probability of exceedance 10% and 2%of the loess liquefaction potential of the sites mentioned above is obtained.

Abstract: The nonlinear dynamic FEM was applied to analyze the dynamic response of a core-wall earth-rock dam on thick loess alluvial deposit. The dynamic responses of acceleration, dynamic displacement, permanent deformation and the liquefaction state of the dam were obtained. Meanwhile, both dynamic FEM limit equilibrium method and pseudo-static method were used to access the seismic resistance of dam slope stability. The results show that dynamic responses of acceleration and dynamic displacement are reasonable. The permanent deformation is mainly concentrated in the core wall. The downstream dam slope has enough seismic resistance stability. However, there will be big dynamic pore-water pressure in the dam foundation and the loess alluvial deposit will be liquefied during the earthquake. Therefore the resistance method of liquefaction should be adopted for the foundation.