Applied Mechanics and Materials Vols. 256-259

Abstract: The stability and the potential seismic capacity of the double-layer elliptic paraboloid latticed shell roof structure of a stadium was analyzed and evaluated, performing by Midas Gen software. Firstly, the seismic response spectrum analyses and the linear time-history analyses were carried out respectively on two different analysis models: the integral structural model containing the lower support structure and the single latticed shell model. The seismic response characteristics and the potential seismic capacity of the models were compared and evaluated. Secondly, based upon the real detailed design of the stadium, the static stability of the latticed shell was analyzed, considering both the geometrical non-linearity and the initial imperfection. Thirdly, the influence of the effects of the vertical ground motion upon the latticed shell structure was studied. The analysis method adopted and the conclusions obtained can be used as references for the future similar engineering projects.

Abstract: An hybrid slip model combining asperity model and k square model was outlined. In the model, both the global and local source parameters follow a trancated normal distribution. The hybrid slip model was then applied to generate finite fault models for the great Wenchuan earthquake, where the fault plane was assumed to have two segments, a reverse segment on the southwestern of the fault and a right-lateral strike-slip segment on the northeastern of the fault. The location of the asperities on each segment was determined considering the results from inversion and field investigation. 30 different finite fault models were obtained, and the one which generates the ground motion best fitting the average spectrum was picked out using spectral deviation evaluation. Finally, ground motion at six near field stations were simualted based on the best-fit fault model and compared to the records.

Abstract: In order to investigate the seismic behavior of earthquake-damaged glass fiber reinforced polymer (GFRP) tubed reinforced concrete(RC) bridge piers repaired with wrapped carbon fiber reinforced polymer (CFRP) sheets. An experimental study, in which four GFRP tubed RC bridge piers repaired with wrapped CFRP sheets were tested under constant axial load and cyclic lateral displacement excursions that simulated seismic force,are presented in this study. Researches show that repaired with CFRP not only increase bridge piers’ultimate strength but also improve the performance such as ductility.

Abstract: In a parallel paper a new High Damping Hybrid Seismic Isolator (HDHSI) has been proposed and obtained by the assembly in series of a Lead Rubber Bearing (LRB) and a Friction Slider (FS) characterized by a high friction coefficient. In the present paper, within the context of seismic base isolation techniques for the earthquake resistance of Reinforced Concrete (RC) buildings, a multi-storey RC building is analyzed as base isolated by the seismic isolator HDHSI (High Damping Hybrid Seismic Isolator). The seismic response of this base isolated RC building is compared with the seismic response of the same structure isolated by a LRB (Lead Rubber Bearing) isolator. The analysis is developed by considering different seismic events in terms of intensity and in terms of frequency content with regard to a supervening collapse. The purpose of this comparative analysis is to highlight the features offered by the HDHSI system compared to the LRB system in the seismic protection of structures. Accordingly, a nonlinear dynamic analysis is performed for a RC structure base isolated by means of the proposed device. In the analysis anomalous seismic events are considered. They are the El Centro earthquake (N00W component, 1940) which is characterized by high intensity and the Erzincan earthquake (N90W component, 1992) which is characterized by anomalous frequency content. The comparison between the two base isolation systems is presented by analyzing the time history of the shear force and the time history of the displacement at the base of the superstructure. The benefits of the HDHSI system in conferring protection to the structure are shown to be significant even under extreme seismic events.

Abstract: In this paper a new seismic base isolator, called High Damping Hybrid Seismic Isolator (HDHSI), is proposed. It is obtained by the assembly in series of a Lead Rubber Bearing (LRB) and a Friction Slider (FS) with a high friction coefficient. The HDHSI device is in contrast with the Resilient-Friction Base Isolator (R-FBI) with the aim of optimizing the Electricité De France (EDF) system. The mathematical model of a structure base isolated by a HDHSI system is analyzed with a two Degree of Freedom System (2-DOF) in which the superstructure is assimilated to a rigid body. Nonlinear finite elements are adopted for modeling the HDHSI device. A dynamic nonlinear analysis is performed and the hysteretic cycles are derived and evaluated for the single components and for the innovative HDHSI device.

Abstract: Currently, there are two magnitude estimation approaches using predominant period for earthquake early warning, Tpmax method and Tc method. We compared Tpmax method with Tc method from the NSMP strong motion records of 22 earthquakes in United States with moment magnitude ranging from 4.1 to 7.9, to explore which method was with higher precision and could be suitable for the earthquake early warning system. Our results show that scaling relations between the two predominant period parameters, Tpmax and Tc, calculated from P-wave arrivals and earthquake magnitude are consistent with previous research. It was found that Tc method had higher precision than Tpmax method with the same filter band, and had best result in magnitude estimation resulting in a correlation coefficient of 0.78 and a standard deviation of 0.16 using 3 seconds signal after the P-wave arrival. We also found that Tc method without low-pass filter had higher accuracy than Tpmax method without low-pass filter. We recommended Tc method using 3 seconds signal after the P-wave arrival as the priority magnitude estimation method for earthquake early warning.

Abstract: Several earthquakes record that the residential fills always suffer severe damages. In order to know the seismic damage mechanism and evaluate the damage extent of residential fill ground, research is carried out on two fill grounds in the eastern part of Kyoto basin. The research includes field survey about terrain condition, geological condition, development history, disaster condition during 1995 Kobe earthquake and surface wave explorations. Some remarkable conclusions are summarized as follows: In Jyodo-ji area, it is a residential fill on soft alluvium ground. The geological condition is back swamp. The thickness of surface fill soil is about 1~4 meters. In Kiyomizu-dera area, it is a valley filled ground. The geological condition is hilly platform.

Abstract: The Maluxiang – Changduhe at Badong County is a newly discovered seismic active fault zone in the Three Gorges Reservoir Area, and the occurrence of fault is EW / N ∠60 °-70 °. The fault appears as a deeply linear valley on the topography and the fault breccia bandwidth is up to 200m. The fault is densely distributed with many springs and covered by luxuriant forests. The new site of Badong County is set up on the top of fault zone, and exists a lot of active landslides. The tested data of the absolute age of the landslides slip zone soil indicates that the landslide is active since the late Pleistocene. The Three Gorges Reservoir has continued seismic activity since 2003, and the fault zone suffers the greatest damage which is the most direct evidence as an indication of fault activity. Therefore, research on the fault zone is very important and significant for immigrant settlement in the Three Gorges reservoir.

Abstract: The two-stage design method for multi-story structures equipped metal dampers is put forward based on the Code for Seismic Design of Buildings (GB50011-2010) and the Code of Japan Society of Seismic Isolation. For preliminary design stage, simplified method is adopted to estimate added stiffness and damping on each story, offering an approximate requirement of dampers. For detail design, the time history analysis is employed to verify the performance of structure with added dampers and determine number of energy dissipation device. In this part, a 10-story frame is analyzed by the new method, and the numerical investigation shows that the new method is simple and flexible for application in engineering.

Abstract: Taken the Dawanglu station of Beijing metro line 14 as engineering background, the seismic performance of metro station by top-down boring with cast-in-situ arch under rare earthquake action (E3) is researched. A three-dimensional dynamic model is established by using the finite element program MIDAS/GTS. Through the time-history analysis method, the displacement response of the main structure of metro station is obtained. The storey relative displacement and storey drift angle of the main structure are mainly analyzed. Numerical results show that under rare earthquake action, metro station structure can satisfy the requirements of the seismic performance, and can be regarded as a valuable reference for the design.