Behavior of axially loaded circular stainless steel tube confined concrete stub columns

A stainless steel tube confined concrete (SSTCC) stub column is a new form of steel-concrete composite column in which the stainless steel tube without bearing the axial load directly is used to confine the core concrete. It could take the advantages of both the stainless steel tube and the confined concrete columns. This paper presents the experimental investigation of circular SSTCC stub columns subjected to axial load. Meanwhile, comparative tests of the circular concrete-filled stainless steel tubes and circular hollow stainless steel tubes were also conducted. The experimental phenomena of specimens are introduced in detail and the experimental results are analyzed. Through the investigation of axial stress and circumference stress on the stainless steel tube, the interaction behavior between stainless steel tube and core concrete is studied. The experimental results showed that the stainless steel tube provides better confinement to the concrete core, thus results the compressive capacity increased obviously comparing with unconfined concrete. The load-carrying capacity of SSTCC stub columns is higher than that of concrete-filled stainless steel tubes. An equation to calculate the load-carrying capacity of SSTCC stub columns was proposed, the results based on calculation are close to the experimental results

Dynamic characteristics and processing of fillers in polyurethane elastomers for vibration damping applications

Polyurethane elastomers have the potential of being used to reduce vibrational noise in many engineering applications. The performance of the elastomer is directly related to matching the nature of the mechanical loss characteristics to the frequency and temperature dependence of the source of the vibration. Materials with a broad frequency response and good mechanical properties are desirable for situations were load bearing and isolation becomes an issue. Because automobile, and other related vehicles operate over a broad temperature range, it is desirable for the damping characteristics of the elastomer to ideally be independent of temperature and frequency. In practice, this is not possible and the creation of materials with a broad spectrum response is desirable. In this paper, the effects of various fillers on the breadth and temperature dependence of the vibration damping characteristics of a filled and crosslinked polyurethane elastomer are explored. The fillers studied are wollastonite, barium sulphate and talc. These materials have different shapes, sizes and surface chemistry and undergo different types of interaction with the matrix. The vibration damping characteristics were further varied by the use of a crosslinking agent. Data presented on the rheological characteristics indicate the strength of the filler-polyol interactions. Dielectric relaxation and dynamic mechanical thermal analysis demonstrate the way in which changes in the type of filler, concentration and amount of crosslinker lead to changes in the location and breadth of the energy dissipation process in these elastomers. The vibration damping characteristics of a selected material are presented to demonstrate the potential of these materials

Numerical Analysis on Bond Strength of FRP Rebars under Elevated Temperature

The bond behaviour between fibre reinforced polymer (FRP) and concrete at a different temperature, ranging from room temperature (20°C) to high temperature of up to 300°C, are modelled using the FEA in this paper. Four different commercially produced FRPs with different bond treatments and the bond properties were study in this temperature range. It is observe that when the temperature increases from 20°C to 300°C the FRP's bond strength reduced between 80 and 90%, however, this reduction for steel is only 38% at this temperature range. Also as the temperature increased a reduction in the bond stiffness has occurred

Estimating Form Factors of Bs→Ds(∗)B_s\rightarrow D_s^{(*)} and their Applications to Semi-leptonic and Non-leptonic Decays

$B_s^0\rightarrow D_s^{-}$ and $B_s^0\rightarrow D_s^{*-}$ weak transition form factors are estimated for the whole physical region with a method based on an instantaneous approximated Mandelstam formulation of transition matrix elements and the instantaneous Bethe-Salpeter equation. We apply the estimated form factors to branching ratios, CP asymmetries and polarization fractions of non-leptonic decays within the factorization approximation. And we study the non-factorizable effects and annihilation contributions with the perturbative QCD approach. The branching ratios of semi-leptonic $B_s^0\rightarrow D_s^{(*)-}l^+\nu_l$ decays are also evaluated. We show that the calculated decay rates agree well with the available experimental data. The longitudinal polarization fraction of $B_s\rightarrow D_s^*V(A)$ decays are $\sim0.8$ when $V(A)$ denotes a light meson, and are $\sim0.5$ when $V(A)$ denotes a $D_q$ ($q=d,s$) meson.Comment: Final version published in J Phys. G 39 (2012) 045002 (Title also changed

On the use of colour reflectivity plots to monitor the structure of the troposphere and stratosphere

The radar reflectivity, defined as the range squared corrected power of VHF radar echoes, can be used to monitor and study the temporal development of inversion layer, frontal boundaries and convective turbulence. From typical featurs of upward or downward motion of reflectivity structures, the advection/convection of cold and warm air can be predicted. High resolution color plots appear to be useful to trace and to study the life history of these structures, particularly their persistency, descent and ascent. These displays allow an immediate determination of the tropopause height as well as the determination of the tropopause structure. The life history of warm fronts, cold fronts, and occlusions can be traced, and these reflectivity plots allow detection of even very weak events which cannot be seen in the traditional meteorological data sets. The life history of convective turbulence, particular evolving from the planetary boundary layer, can be tracked quite easily. Its development into strong convection reaching the middle troposphere can be followed and predicted

Quantum resonance and anti-resonance for a periodically kicked Bose-Einstein Condensate in a one dimensional Box

We investigate the quantum dynamics of a periodically kicked Bose-Einstein Condensate confined in a one dimensional (1D) Box both numerically and theoretically, emphasizing on the phenomena of quantum resonance and anti-resonance. The quantum resonant behavior of BEC is different from the single particle case but the anti-resonance condition ($T = 2\pi$ and $\alpha = 0$) is not affected by the atomic interaction. For the anti-resonance case, the nonlinearity (atom interaction) causes the transition between oscillation and quantum beating. For the quantum resonance case, because of the coherence of BEC, the energy increase is oscillating and the rate is dramatically affected by the many-body interaction. We also discuss the relation between the quantum resonant behavior and the KAM or non-KAM property of the corresponding classical system.Comment: 7 pages, 7 figure

Pointwise estimates for the Bergman kernel of the weighted Fock space

We prove upper pointwise estimates for the Bergman kernel of the weighted Fock space of entire functions in $L^2(e^{-2\phi})$ where $\phi$ is a subharmonic function with $\Delta \phi$ a doubling measure. We derive estimates for the canonical solution operator to the inhomogeneous Cauchy-Riemann equation and we characterize the compactness of this operator in terms of $\Delta \phi$