Impact of ground-motion duration on nonlinear structural performance: Part II: site- and building-specific analysis

This study’s Part I proved that ground-motion duration could play an important role when assessing the nonlinear structural performance of case-study inelastic single degree-of-freedom systems. However, quantifying duration effects in many practical/more realistic engineering applications is not trivial, given the difficulties in decoupling duration from other ground-motion characteristics. This study’s Part II, introduced in this article, explores the impact of duration on nonlinear structural performance by numerically simulating the structural response of realistic case-study reinforced concrete bare and infilled building frames. Advanced computational models incorporating structural components’ cyclic and in-cycle strength and stiffness deterioration, and destabilizing (Formula presented.) effects are used. The proposed methodology relies on the generalized conditional intensity measure approach to select ground motions. This allows selecting records consistent with the seismic hazard at a target site, both in terms of spectral shape and duration. Those are employed as input to cloud-based nonlinear structural response analyses. Variance analysis is used to quantify the impact of duration on structural response. Furthermore, vector-valued fragility and vulnerability models alternatively using peak- and cumulative-based engineering demand parameters are derived. Results show that higher damage/loss estimates can be attained as ground-motion duration increases. Relative differences up to 44% are found in fragility median values for a pre-code reinforced concrete infilled frame when comparing scalar and vector-valued fragility models conditioned on average pseudo-spectral acceleration and significant durations up to 35 s

Impact of ground-motion duration on nonlinear structural performance: Part I: spectrally equivalent records and inelastic single-degree-of-freedom systems

In current seismic performance-based assessment approaches, nonlinear dynamic analysis of structures generally relies on ground motions selected based on their pseudo-spectral accelerations, with little or no consideration for ground-motion duration. Part I of this study, presented in this article, attempts to comprehensively quantify the impact of ground-motion duration on the nonlinear structural performance of case-study inelastic single-degree-of-freedom systems for shallow-crustal seismicity conditions. The effect of duration is decoupled from that of ground-motion amplitude and spectral shape by assembling sets of spectrally equivalent long- and short-duration records. Such sets are employed in incremental dynamic analyses of a wide range of computational models incorporating in-cycle and cyclic strength and stiffness deterioration. The structural response is quantified in terms of peak- and cumulative-based engineering demand parameters. Formal hypothesis testing is used to assess the statistical significance of duration’s impact on the median structural capacity of the considered structural systems. Furthermore, the derivation of duration-dependent fragility and vulnerability relationships demonstrates that ground-motion duration effectively impacts the nonlinear structural performance of various systems, and it should be accounted for in current practice. The fragility median values for highly deteriorating structural systems under long-duration ground motions are found to be up to 21% or 34.0% smaller than the short-duration counterpart if a peak- or cumulative-based engineering demand parameter is adopted, respectively

Investigating ground-motion duration effects on building portfolio loss estimates

Earthquake-induced ground-motion duration can be an important factor to consider when assessing ground-motion damage potential, as evidenced by recent earthquake events worldwide. In current practice, duration is commonly relegated to implicit, qualitative considerations. This study introduces a framework to explicitly quantify the influence of duration on building portfolio direct economic losses. To this end, a simulation-based probabilistic risk modelling framework is developed for different synthetic building portfolios impacted by a case-study seismic source. Two building typologies, representative of distinct vulnerability classes in southern Europe, are considered. A simulation-based probabilistic seismic hazard analysis is performed, explicitly simulating duration jointly with spectral-shape-related intensity measures. Sets of long and one-to-one spectrally-equivalent short duration ground-motion records are selected and then used jointly to perform nonlinear dynamic analysis and derive fragility models for each considered building typology. Fragility relationships are derived by using average spectral acceleration as the primary intensity measure and: 1) maximum inter-storey drift ratio as a demand parameter, indirectly accounting for ground-motion duration (through the adopted nonlinear modelling strategy); 2) maximum inter-storey drift ratio as demand parameter, explicitly considering duration as an intensity measure together with spectral shape, in a vector-valued format. For each case, vulnerability models are developed by combining the fragility relationships with a building-level damage-to-loss model. The portfolio expected annual losses estimated using the described vulnerability models are critically compared and discussed. Depending on the location/portfolio, the impact of ground-motion duration can be significant, and the proposed approaches allow an analyst to account for it in a practical way

Proper incorporation of self-adjoint extension method to Green's function formalism : one-dimensional δ′\delta^{'}-function potential case

One-dimensional $\delta^{'}$-function potential is discussed in the framework of Green's function formalism without invoking perturbation expansion. It is shown that the energy-dependent Green's function for this case is crucially dependent on the boundary conditions which are provided by self-adjoint extension method. The most general Green's function which contains four real self-adjoint extension parameters is constructed. Also the relation between the bare coupling constant and self-adjoint extension parameter is derived.Comment: LATEX, 13 page

Protocolos para extração do DNA-proviral e PCR do lentivírus caprino em sangue.

bitstream/CNPC/20248/1/cot72.pd

POTENTIAL OF ILMENITE AS A SOLAR ABSORBER

Titanium is considered the fourth most widely used material in industry worldwide. Titanium minerals are currently being applied in various branches of industry, mainly in the field of pigmentation. Ilmenite (FeTiO3) is an iron and titanium oxide of more common and abundant occurrence, with theoretical composition of Fe (36.8%), Ti (31.6%) and O (31.6%). Having regard to the potential of titanium minerals and the abundance of ilmenite, together with the importance of validating direct applications of this ore, since the processing of titanium is still complex and expensive, it is necessary to study this mineral and the knowledge of its main characteristics. This work brings thermal, chemical and mineralogical characterizations of ilmenite, in order to know the potential of application of this ore as a solar absorbing material. The characterization techniques used were: X-ray diffraction (XRD) and Rietveld refinement for phase quantification, X-ray fluorescence (XRF), optical spectroscopy in the middle infrared region with Fourier Transformation by Transmittance (FTIR) and thermogravimetric thermal analysis (TGA). The analyzed sample obtained X-ray diffractogram, ilmenite (80.6%) and rutile (19.4%) as significant phases, corroborating the FRX results that indicated greater presence of Fe and titanium oxide in the ilmenite chemical composition under study. The TGA, DTA and DSC analyses indicated good thermal stability of the material in medium and high temperatures. The integration of the obtained data shows that the application of this ore as a precursor material of absorber films for selective purposes is considerable

The amyloidogenic potential and behavioral correlates of stress

Observations of elevated basal cortisol levels in Alzheimer's disease (AD) patients prompted the hypothesis that stress and glucocorticoids (GC) may contribute to the development and/or maintenance of AD. Consistent with that hypothesis, we show that stress and GC provoke misprocessing of amyloid precursor peptide in the rat hippocampus and prefrontal cortex, resulting in increased levels of the peptide C-terminal fragment 99 (C99), whose further proteolytic cleavage results in the generation of amyloid-beta (Abeta). We also show that exogenous Abeta can reproduce the effects of stress and GC on C99 production and that a history of stress strikingly potentiates the C99-inducing effects of Abeta and GC. Previous work has indicated a role for Abeta in disruption of synaptic function and cognitive behaviors, and AD patients reportedly show signs of heightened anxiety. Here, behavioral analysis revealed that like stress and GC, Abeta administration causes spatial memory deficits that are exacerbated by stress and GC; additionally, Abeta, stress and GC induced a state of hyperanxiety. Given that the intrinsic properties of C99 and Abeta include neuroendangerment and behavioral impairment, our findings suggest a causal role for stress and GC in the etiopathogenesis of AD, and demonstrate that stressful life events and GC therapy can have a cumulative impact on the course of AD development and progression.CC and IS were supported by stipends from the Max Planck Society and EU Marie Curie Training Fellowships (at University College London, UK). The collaboration between the German and Portuguese laboratories was supported through the German–Portuguese Luso-Alemas Program (DAAD/GRICES). This study was conducted within the framework of the EU-supported integrated project ‘CRESCENDO’ (Contract FP6-018652)