1、中文 7000 字，英文 3900 单词 出处： Matsagar V A, Jangid R S. Influence of isolator characteristics on the response of base-isolated structuresJ. Engineering Structures, 2004, 26(12):1735-1749. 本科毕业设计（论文）外文翻译译文 学生姓名 ： 院 （系）： 机 械工程学院 专业班级 ： 指导教师 ： 完成日期 ： Influence of isolator characteristics on the response of
2、base-isolated structure Vasant A. Matsaar 1Z.S. Janids Abstract The influence of isolator characteristics on the seismic response of multi-story base-isolated structure is investigated. The isolated building is modeled as a shear type structure with lateral degree-of-freedom at each floor. The isola
3、tors are modeled by using two different mathematical models depicted by bi-linear hysteretic and equivalent linear elastic-viscous behaviors. The coupled differential equations of motion for the isolated system are derived and solved in the incremental form using Newmarks step-by-step method of inte
4、gration. The variation of top floor absolute acceleration and hearing displacement for various bi-linear systems under different earthquakes is computed to study the effects of the shape of the isolator hysteresis loop. The influence of the shape of isolator force-deformation loop on the response of
5、 isolated structure is studied under the variation of important system parameters such as isolator yield displacement, superstructure flexibility, isolation time period and number of story of the base-isolated structure. It is observed that the code specified equivalent linear elastic viscous dampin
6、g model of a bi-linear hysteretic system overestimates the design bearing displacement and underestimates the superstructure acceleration. The response of base-isolated structure is significantly influenced by the shape of hysteresis loop of isolator. The low value of yield displace- ment of isolato
7、r (i.e. sliding type isolation systems) tends to increase the superstructure accelerations associated with high frequencies. Further, the superstructure acceleration also increases with the increase of the superstructure flexibility. keywords: Base isolation； Earthquake； Elastomtric bearing Sliding
8、system； Bearing displacement； Superstructure acceleration； Bi-linear hysteresis； Equivalent linear. 1 Introduction Seismic isolation, which is now recognized as a mature and efficient technology, can be adopted to improve the seismic performance of strategically important buildings such as schools,
9、hospitals, industrial structures etc., in addition to the places where sensitive equipments are intended to protect from hazardous effects during earthquake 1-3. Based on the extent of control to be achieved over the seismic response, the choice of the isolation system varies and thereupon its desig
10、n is done to suit the requirements of use of the structure. In seismically base-isolated systems, the superstructure is decoupled from the earthquake ground motion by introducing a flexible interface between the foundation and the base of structure. Thereby, the isolation system shifts the fundament
11、al time period of the structure to a large value and/or dissipates the energy in damping, limiting the amount of force that can be transferred to the super structure such that inter-story drift and floor accelerations are reduced drastically. The matching of fundamental frequencies of base-isolated
12、structures and the predominant frequency contents of earthquakes is also consequently avoided, leading to a flexible structural system more suitable from earthquake resistance viewpoint. The two most common types of base isolation systems adopted in practice utilize either rubber bearings or sliding
13、 systems between the foundation and superstructure for the purpose of isolation from ground motions in the buildings as well as bridges. It is very essential to understand the different parameters affecting the response of base-isolated structure when used for seismic protection of the structures. E
14、specially in case of the base-isolated structures, that houses sensitive equipments, determination of acceleration imparted and associated peak displacement are the key issues for the design engineer 4. Moreover, the pounding and structural impacts in case of baseisolated structures made upon the ad
15、jacent structures, when separation gap distances are inadequate, become a major concern because these phenomena may lead to catastrophic failures leading to immense isolator damage. Such failures and damages can be avoided by properly estimating the peak isolator displacement and recommendation of a
16、ppropriate isolation gap distances. In order to predict peak displacement and determine accurate separation gap distance requirement for a base-isolated structure, it is mandatory to know, in prior, the different parameters that affect the bearing displacement and its consequent effect on the supers
17、tructure acceleration. The failures due to such impacts can be avoided by reducing the peak bearing displacement by compromising with increase in superstructure acceleration to an acceptable level i.e. tolerable reduction in effectiveness of isolation. Selection of different parameters characterizin
18、g an isolation system is important in view of keeping a control over response quantities especially the excessive bearing displacement at isolator level. The behavior of isolation systems and the baseisolated structures is now well established and codes are developed for designing the base-isolated
19、structures59. For non-linear isolation systems, the codes allow to use the equivalent linear model to permit the use of response spectrum method for designing the isolated structures. The equivalent linear models are based on the effective stiffness at the design displacement and the equivalent visc
20、ous damping is evaluated from the area of the hysteresis loop. The comparison of equivalent linear and actual non-linear model for the response of isolated bridge structures had been demonstrated in thepast 1013 and shown that the equivalent linear model can be used for predicting the actual non-lin
21、ear response of the system. However, the above studies were restricted to the bridge idealized as a rigid body and the non-linear behavior of the isolator was limited to the leadrubber bearings idealized by bi-linear characteristics. The equivalent linear model may give different response of isolate
22、d structures in comparison to the actual non-linear model for flexible superstructures and the type of non-linear hysteresis loop of the isolator associated with sliding type isolation systems. Therefore, it will be interesting to study the comparison of the two models for different hysteretic behav
23、ior of the isolator and the system parameters. Here-in, the seismic response of multi-story structure supported on non-linear base isolation systems is investigated. The specific objectives of the study are: (i) to compare the seismic response of base-isolated flexible building obtained from various
24、 bi-linear hysteretic model and its equivalent linear model； (ii) to study the influence of shape of the isolator hysteresis loop and its parameters (i.e. yield displacement and force) on the effectiveness of the isolation system and (iii) to investigate the effects of superstructure flexibility on
25、the response of base-isolated structures. 2. Structural model of base-isolated building Fig. 1(a) shows the idealized mathematical model of the N-story base-isolated building considered for the present study. The base-isolated building is modeled as a shear type structure mounted on isolation system
26、s with one lateral degree-of-freedom at each floor. Following assumptions are made for the structural system under consideration: 1. The superstructure is considered to remain within the elastic limit during the earthquake excitation. This is a reasonable assumption as the isolation attempts to redu
27、ce the earthquake response in such a way that the structure remains within the elastic range. 2. The floors are assumed rigid in its own plane and the mass is supposed to be lumped at each floor level. 3. The columns are inextensible and weightless providing the lateral stiffness. 4. The system is subjected to single horizontal component of the earthquake ground motion. 5. The effects of soilstructure interaction are not taken into consideration.
