373,051 research outputs found
The Influence of Base Isolation to the Required Ductility of Soft Storey Buildings
The Response Spectrum Analysis of the structures is based on the allowable ductility considered for that structure. In the case of a multi-degree-of-freedom buildings, the required ductility cannot be the same with the allowable ductility; furthermore, the required ductility values are different for different storey. In the case of first soft/weak storey building, the required ductility of this storey is much higher compared to allowable ductility and impossible to achieve. Nowadays there are many cases of existing reinforced concrete structures with the possibility of soft/weak storey. Even new structures are required to have open space at ground floor level as the owners want them for shops or garages usage.
This paper analyses the influence of base isolation to the required storey ductility of weak storey buildings. A five storey shear frame type structure is considered as the model. The elastic and elasto-plastic modelling of the structural elements and bilinear modelling of rubber isolators are used. Linear Response Spectrum analysis and Nonlinear Time History analysis are performed in order to determine the required storey ductility for the existing and new soft/weak storey buildings using the SAP2000 computer program.
The analysis results show the reduction of the required storey ductility due to the application of base isolation not only in new structures, but in existing structures too. This means that the base isolation technique is a good alternative to be applied in buildings with first soft/weak storey structure
ON SOME SUBSETS OF SOFT WEAK STRUCTURES
The main purpose of this paper, is to list the main properties which give the deviations between soft weak structure [15] and thats in soft topological spaces [14] and supra soft topological spaces [6], which is supported by counter examples. Moreover, we introduce and study the basic properties of the soft structures π(swo), σ(swo), α(swo), β(swo) and ρ(swo). It has been pointed out in this paper that many of these parameters studied have, in fact, applications in real world situations and therefore I believe that this is an extra justification for the work conducted in this paper.
Determining the Structure of Supersymmetry-Breaking with Renormalization Group Invariants
If collider experiments demonstrate that the Minimal Supersymmetric Standard
Model (MSSM) is a good description of nature at the weak scale, the
experimental priority will be the precise determination of superpartner masses.
These masses are governed by the weak scale values of the soft supersymmetry
(SUSY)-breaking parameters, which are in turn highly dependent on the
SUSY-breaking scheme present at high scales. It is therefore of great interest
to find patterns in the soft parameters that can distinguish different high
scale SUSY-breaking structures, identify the scale at which the breaking is
communicated to the visible sector, and determine the soft breaking parameters
at that scale. In this work, we demonstrate that 1-loop Renormalization
Group~(RG) invariant quantities present in the MSSM may be used to answer each
of these questions. We apply our method first to generic flavor-blind models of
SUSY-breaking, and then examine in detail the subset of these models described
by General Gauge Mediation and the constrained MSSM with non-universal Higgs
masses. As RG invariance generally does not hold beyond leading-log order, we
investigate the magnitude and direction of the 2-loop corrections. We find that
with superpartners at the TeV scale, these 2-loop effects are either
negligible, or they are of the order of optimistic experimental uncertainties
and have definite signs, which allows them to be easily accounted for in the
overall uncertainty.Comment: v2 -- references added, version to be published in PRD; 40 page
Soft modes near the buckling transition of icosahedral shells
Icosahedral shells undergo a buckling transition as the ratio of Young's
modulus to bending stiffness increases. Strong bending stiffness favors smooth,
nearly spherical shapes, while weak bending stiffness leads to a sharply
faceted icosahedral shape. Based on the phonon spectrum of a simplified
mass-and-spring model of the shell, we interpret the transition from smooth to
faceted as a soft-mode transition. In contrast to the case of a disclinated
planar network where the transition is sharply defined, the mean curvature of
the sphere smooths the transitition. We define elastic susceptibilities as the
response to forces applied at vertices, edges and faces of an icosahedron. At
the soft-mode transition the vertex susceptibility is the largest, but as the
shell becomes more faceted the edge and face susceptibilities greatly exceed
the vertex susceptibility. Limiting behaviors of the susceptibilities are
analyzed and related to the ridge-scaling behavior of elastic sheets. Our
results apply to virus capsids, liposomes with crystalline order and other
shell-like structures with icosahedral symmetry.Comment: 28 pages, 6 figure
A Three-Dimensional Dynamic Supramolecular "Sticky Fingers" Organic Framework.
Engineering high-recognition host-guest materials is a burgeoning area in basic and applied research. The challenge of exploring novel porous materials with advanced functionalities prompted us to develop dynamic crystalline structures promoted by soft interactions. The first example of a pure molecular dynamic crystalline framework is demonstrated, which is held together by means of weak "sticky fingers" van der Waals interactions. The presented organic-fullerene-based material exhibits a non-porous dynamic crystalline structure capable of undergoing single-crystal-to-single-crystal reactions. Exposure to hydrazine vapors induces structural and chemical changes that manifest as toposelective hydrogenation of alternating rings on the surface of the [60]fullerene. Control experiments confirm that the same reaction does not occur when performed in solution. Easy-to-detect changes in the macroscopic properties of the sample suggest utility as molecular sensors or energy-storage materials
A Chandra X-ray Study of Cygnus A - II. The Nucleus
We report Chandra ACIS and quasi-simultaneous RXTE observations of the
nearby, powerful radio galaxy Cygnus A, with the present paper focusing on the
properties of the active nucleus. In the Chandra observation, the hard (> a few
keV) X-ray emission is spatially unresolved with a size \approxlt 1 arcsec (1.5
kpc, H_0 = 50 km s^-1 Mpc^-1) and coincides with the radio and near infrared
nuclei. In contrast, the soft (< 2 keV) emission exhibits a bi-polar nebulosity
that aligns with the optical bi-polar continuum and emission-line structures
and approximately with the radio jet. In particular, the soft X-ray emission
corresponds very well with the [O III] \lambda 5007 and H\alpha + [N II]
\lambda\lambda 6548, 6583 nebulosity imaged with HST. At the location of the
nucleus there is only weak soft X-ray emission, an effect that may be intrinsic
or result from a dust lane that crosses the nucleus perpendicular to the source
axis. The spectra of the various X-ray components have been obtained by
simultaneous fits to the 6 detectors. The compact nucleus is detected to 100
keV and is well described by a heavily absorbed power law spectrum with
\Gamma_h = 1.52^{+0.12}_{-0.12} (similar to other narrow line radio galaxies)
and equivalent hydrogen column N_H (nuc) = 2.0^{+0.1}_{-0.2} \times 10^{23}
cm^-2.
(Abstract truncated).Comment: To be published in the Astrophysical Journal, v564 January 1, 2002
issue; 34 pages, 11 figures (1 color
MODELLING OF REINFORCED SOIL
Geosynthetics are being used increasingly to improve soil properties and to
obtain better performance from soft or weak foundation sites. It is well-known
that the overall stability is improved and that the movement of the
structures founded on the reinforced soil reduces because of the
mobilization of tensile forces in geosynthetics. This force is well
quantified in the analysis of stability of structures constructed with
reinforced soil. However, studies on modelling aspects are not many. In this
paper, models are considered to quantify the effect of tensile force.
Solutions for an embankment (strip) type of load are presented
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