Non-linear finite element analysis for prediction of seismic response of buildings considering soil-structure interaction

The objective of this paper focuses primarily on the numerical approach based on two-dimensional (2-D) finite element method for analysis of the seismic response of infinite soil-structure interaction (SSI) system. This study is performed by a series of different scenarios that involved comprehensive parametric analyses including the effects of realistic material properties of the underlying soil on the structural response quantities. Viscous artificial boundaries, simulating the process of wave transmission along the truncated interface of the semi-infinite space, are adopted in the non-linear finite element formulation in the time domain along with Newmark's integration. The slenderness ratio of the superstructure and the local soil conditions as well as the characteristics of input excitations are important parameters for the numerical simulation in this research. The mechanical behavior of the underlying soil medium considered in this prediction model is simulated by an undrained elasto-plastic Mohr-Coulomb model under plane-strain conditions. To emphasize the important findings of this type of problems to civil engineers, systematic calculations with different controlling parameters are accomplished to evaluate directly the structural response of the vibrating soil-structure system. When the underlying soil becomes stiffer, the frequency content of the seismic motion has a major role in altering the seismic response. The sudden increase of the dynamic response is more pronounced for resonance case, when the frequency content of the seismic ground motion is close to that of the SSI system. The SSI effects under different seismic inputs are different for all considered soil conditions and structural types

The impact of Giant Anatolian Project (GAP) of Turkey on cotton production pattern and fibre properties

In Turkey, which is the sixth largest cotton producer in the world, cottons are mainly categorised and priced according to their location, as the Aegean cotton category and the remained Turkish regions category since it is believed that Aegean cotton has superior properties compared to the other regions of the country. However a large national project, called the South Anatolian Project (GAP) aims to improve the irrigation and agricultural capacity of the southeast region; it has been nearly completed and is expected to change the cotton picture of the country significantly. Recent figures indicate that cotton production areas are shifting from the west to the southeast, mainly as a result of GAP. Following this new trend, a change in fibre properties is also expected. In this research work, we examined the physical properties of cotton samples of known varieties taken from 19 different regions. The samples were tested on an Uster HVI Spectrum for fibre properties, and then the effect of location was evaluated. The test results indicate that some cotton varieties in the southeast part of the country have better cotton properties than the same variety in the Aegean region. This result confirms that the current standardisation method used in Turkey is out of date and should be changed in the near future. We also compared test results with Uster World Statistics. In general, Aegean-region cottons seem to be getting coarser in recent years, while some varieties in the southeast region are longer, finer, more mature and have better elongation values. However, in the southeast parts, picking and ginning techniques should be improved for cleaner cottons

The effect of material and thickness of collector electrode on fiber fineness in electrospinning

AATCC;INDA;TAPPI;The Fiber Society2010 Spring Conference of the Fiber Society -- 12 May 2010 through 14 May 2010 -- Bursa -- 105817[No abstract available

Deformation of yarn cross-section in relation to yarn structure

An apparatus is described which imitates the yarn deformation typically occurring in most textile processes, especially where a yarn passes around small diameter rods under tension. With this apparatus, a yarn specimen is suspended cross-wise over a horizontal rod, tension is then applied to the ends of the yarn and the changes in both major and minor diameters of the deformed yarn cross-section are measured. A series of experiments using filament, ring-spun and open-end spun yarns was carried out in order to determine the effect of yarn structure on the deformation of the yarn cross-section

A micro-macro approach to rubber-like materials?Part I: the non-affine micro-sphere model of rubber elasticity

The contribution presents a new micro-mechanically based network model for the description of the elastic response of rubbery polymers at large strains and considers details of its numerical implementation. The approach models a rubber-like material based on a micro-structure that can be symbolized by a micro-sphere where the surface represents a continuous distribution of chain orientations in space. Core of the model is a new two-dimensional constitutive setting of the micro-mechanical response of a single polymer chain in a constrained environment defined by two micro-kinematic variables: the stretch of the chain and the contraction of the cross section of a micro-tube that contains the chain. The second key feature is a new non-affine micro-to-macro transition that defines the three-dimensional overall response of the polymer network based on a characteristic homogenization procedure of micro-variables defined on the micro-sphere of space orientations. It determines a stretch fluctuation field on the micro-sphere by a principle of minimum averaged free energy and links the two micro-kinematic variables in a non-affine format to the line-stretch and the area-stretch of the macro-continuum. Hence, the new model describes two superimposed contributions resulting from free chain motions and their topological constraints in an attractive dual geometric structure on both the micro- and the macro-level. Averaging operations on the micro-sphere are directly evaluated by an efficient numerical integration scheme. The overall model contains five effective material parameters obtained from the single chain statistics and properties of the network with clearly identifiable relationships to characteristic phenomena observed in stress-strain experiments. The approach advances features of the affine full network and the eight chain models by a substantial improvement of their modeling capacity. The excellent predictive performance is illustrated by comparative studies with previously developed network models and by fitting of various available experimental data of homogeneous and non-homogeneous tests