Experimental assessment and retrofit of full-scale models of existing RC frames

PSD tests on two full-scale models of existing non-seismic resisting RC frame structures are described. The testing program covered several aspects, namely assessment of seismic performance of existing frames without and with infill panels, retrofitting of the bare frame using Selective Retrofitting techniques, strengthening of the infill panels using shotcrete and retrofitting of the frame using K-bracing with shear-link dissipators. The main results from the tests are summarized and discussed and the conclusions are drawn. The tests on the bare frame have shown how vulnerable are existing structures constructed in the 60’s and the beneficial effects of infill panels were confirmed from the tests on the infilled frame. Important improvements, in terms of seismic performance, were achieved by the retrofitting of the frames. However, it was also confirmed that strengthening of the existing infill panels in poorly detailed frames may lead to dangerous ‘local’ failures, such as the shear out of the external columns

Effective action in DSR1 quantum field theory

We present the one-loop effective action of a quantum scalar field with DSR1 space-time symmetry as a sum over field modes. The effective action has real and imaginary parts and manifest charge conjugation asymmetry, which provides an alternative theoretical setting to the study of the particle-antiparticle asymmetry in nature.Comment: 8 page

Schwinger's Method for the Massive Casimir Effect

We apply to the massive scalar field a method recently proposed by Schwinger to calculate the Casimir effect. The method is applied with two different regularization schemes: the Schwinger original one by means of Poisson formula and another one by means of analytical continuation.Comment: plain TeX, 6 pages, DFTUZ-93-2

A modified Schwinger's formula for the Casimir effect

After briefly reviewing how the (proper-time) Schwinger's formula works for computing the Casimir energy in the case of "scalar electrodynamics" where the boundary conditions are dictated by two perfectly conducting parallel plates with separation "a" in the Z-axis, we propose a slightly modification in the previous approach based on an analytical continuation method. As we will see, for the case at hand our formula does not need the use of Poisson summation to get a (renormalized) finite result.Comment: 6 pages, DFTUZ/93/14 (a short version will appear in the Letters in Math. Phys.

Frequency and damping evolution during experimental seismic response of civil engineering structures

The results of the seismic tests on several reinforced-concrete shear walls and a four-storey frame are analysed in this paper. Each specimen was submitted to the action of a horizontal accelerogram, with successive growing amplitudes, using the pseudodynamic method. An analysis of the results allows knowing the evolution of the eigen frequency and damping ratio during the earthquakes thanks to an identification method working in the time domain. The method is formulated as a spatial model in which the stiffness and damping matrices are directly identified from the experimental displacements, velocities and restoring forces. The obtained matrices are then combined with the theoretical mass in order to obtain the eigen frequencies, damping ratios and modes. Those parameters have a great relevance for the design of this type of structures

An analysis of average annual pay and cost-of-living in U.S. metropolitan regions: Working paper series--02-28

One of the key factors in the decision to relocate or migrate from one location to another involves whether or not the migrant's economic status is enhanced by the move. The potential for improved economic status plays a significant role in the migration decision. Therefore, it is important to know whether relocation to a new area improves the economic welfare of the migrant. One means to determine the answer is to compare annual pay in each region with the relative cost-of-living there. This paper examines the relationship between "average annual pay" in 2000 for cities in 219 metropolitan areas and the cost of living in these same locations. A regression analysis was performed for cities in the 219 Metropolitan Statistical Areas. Additional regressions were performed after grouping these cities within the four U.S. Census Regions. The results allow us to determine the strength of the relationship between annual pay and cost-of-living variables in these locations, and also if different patterns emerge among the four census regions of the economy. Additional variables were included to determine if city size, climate, or education impact the relationship

Los riesgos geológicos en la Ordenación Territorial

There are wide areas of the planet where the incidence of natural catastrophes is very high, particularly in areas with high population density or where areas under natural risks are occupied. Most of these areas belong to a clear tectonic setting.In addition, public awareness on these natural catastrophic phenomenon acquires nowadays an additional dimension due to the important role of mass media. Mass media informs immediately al1 over the world on these caastrophes, for example, the big earthquakes (Mexico, California, Japan), landslides, floods, eruptions, hurricanes, etc.These geological phenomena are caused by the normal processes within the earth's crust, which have social and economic consequences. These processes have shaped our planet,with more or less dramatic consequences depending on their speed and intensity.Catastrophic events are gauged by their environmental effects, mainly on the biosphere. Socioeconomic disasters have also augmented as the increase and concentration of population have increased the risk on populated areas.Finally, the necessity of preventive measures is clear on global risks, such as the effects of global warming of those resulting from the management of water resources.

On the Electronic Transport Mechanism in Conducting Polymer Nanofibers

Here, we present theoretical analysis of electron transport in polyaniline based (PANi) nanofibers assuming the metalic state of the material. To build up this theory we treat conducting polymers as a special kind of granular metals, and we apply the quantum theory of conduction in mesoscopic systems to describe the transport between metallic-like granules. Our results show that the concept of resonance electron tunneling as the predominating mechanism providing charge transport between the grains is supported with recent experiments on the electrical characterization of single PANi nanofibers. By contacting the proposed theory with the experimental data we estimate some important parameters characterizing the electron transport in these materials. Also, we discuss the origin of rectifying features observed in current-voltage characteristics of fibers with varying cross-sectional areas.Comment: 5 pages, 1 figure, accepted for publication in Phys. Rev. B, Vol.72, xxxx (2005