Sharif Digital Repository

Investigation of the dynamic characteristics of an existing structure system based on field tests is of practical significance, since it can be employed in the field of examining construction quality, validating or improving analytical finite element structural models, or conducting damage assessment. The main purpose of this study is to investigate the dynamic characteristics of dams using the seismic response data. Whereas, in the process of frequency domain identification of dam properties, frequency response function (FRF) plays the most important role, evaluating the corresponding parameters with better accuracy has always been desirable. Therefore, a comparison was made between some... 

In this thesis, asymmetric information is tested by using the dynamic information of automobile policyholders in Iran Insurance company(IIC). Tests were conducted with the Conditional Independence Bivariate Probit model which have been provided in Chiappori and Salanie(2000) and Dynamic Properties which is presented for bonus/malus system in Abbring et al(2003) and econometric method Dynamic Bivariate Probit Model which have been pioneered in Dionne et al(2004). By using a sample of policyholders in IIC, 86637, Our finding confirms positive correlation between risk and coverage in Bivariate Probit Model, which supports hypothesis of presence of asymmetric information. Also, There is negative... 

In the past few decades, shaking tables are widely used to evaluate system response of structures under seismic excitations. These devices are used without any fundamental research performed on a shaking table system as an entity model. In most of these studies for simplicity, it is assumed that there exist no considerable vibration and displacement around the shaking tables, and no attention is paid to the peripheral substances such as soil settled under the foundation.
In this thesis, result of ambient vibration test on shaking table system (solid deck, concrete foundation and soil layer) has been presented. Precise sensors known as low frequency and high accuracy accelerometers have... 

Base flexibility of structures, cause changes in seismic input motions to the structure, and hence, result in variations in structural seismic responses. This phenomenon is commonly referred to as soil-structure interaction (SSI). The effect of base flexibility on seismic responses is usually investigated from two main aspects: 1) Kinematic interaction (KI) , 2) Inertial Interaction (II). KI effects are induced, first, because of the stiffness contrast between the foundation and the flexible base, and second, because of phase difference of the receiving waves in the contact boundary between the foundation and the flexible base. These effects may results in variations in frequency content of... 

For the sake of decrease in energy and force of earthquake, seismic isolators are used. Regular seismic isolators are too heavy and damaged by chemical materials, therefore in this research a new approach is used that steel shim plates replaced by carbon and polyamide fibers. The aim of this research is to obtain the dynamic and mechanical properties of carbon and polyamide fiber reinforced isolators in comparison with steel reinforced isolators. In this approach, firstly some specimens have been designed and manufactured, then compresional and cyclic shear tests were carried out on them. All three type isolators are cylindrical and have identical diameter and height. The steel, carbon fiber... 

Evaluation of the compression wave velocity (Vp ) and small strains elastic modulii of various types of plastic concrete specimens in unconfined and triaxial compression tests using piezoelectric transducers was performed in this study. Plastic concrete consists of aggregates, cement, water and bentonite, mixed at a high water cement ratio, to produce a ductile material. It is used for creating an impermeable cut-off wall for seepage control in highly permeable dam foundations. A plastic concrete cut-off wall acts essentially as a barrier to stop or reduce the groundwater flow. In this study the effect of specimen age, water-cement ratio, bentonite-cement ratio, confining pressure, wave... 

In order to simplify the dynamic analysis of soil-structure systems, the structural element of the foundation is usually assumed to be rigid. While the rigid foundation assumption is acceptable for block-type machine foundations, it may influence the dynamic response of other structures such as structures with a central rigid core. Previous research has shown that the flexibility of the foundation structural elements affect dynamic stiffness of underlying soil so it can change the structural response. The aim of this thesis is to study the influence of foundation flexibility on the global response of soil-structure systems including structures with a rigid core. Since the response of the... 

Loess soil layers in semi-arid to arid areas have been deposited through the accumulation of aeolian sediments, resulted in a special metastable and open structure being usually unsaturated in nature. Since naturally occurred loess is widespread, it has been recently considered as a promising resource for constructing earth-fill structures. However, due to different microstructures of intact and recompacted loess, different responses to hydraulic and mechanical loading would be expected. Up to now, the hydro-mechanical behavior of loess from different perspectives has not been linked to its microstructural characteristics. The current research, therefore, aims to provide insight into the... 

This thesis aims to provide a method to obtain the radial dynamic properties of rolling element bearing, including stiffness and damping by experimental test methods. Methods such as modal test, vibration test, and static tests were known as experimental methods to obtain these properties, and in this research, all three of these methods were used to obtain these properties. After studying the theoretical relations governing the stiffness coefficients of the bearings, a test bed platform was designed and built to conduct the tests After the construction of this platform, the test design stage was reached done and different parameters changed during these tests several tests were it is noted...