The Role of Mass Eccentricity on the Earthquake Induced  Torsion in Buildings

This paper investigates the effect of mass eccentricity on the earthquake induced torsion in buildings. An analytical solution is proposed, which identifies the location of a key structural element for which the torsional response of a structure is minimized for any height wise variation of the mass eccentricities. The accuracy of the analytical solution is then verified with parametric numerical modelling on 9-story buildings with height wise variations of the accidental eccentricities. The numerical modeling results show that the top rotations and base torques have an inverted peak, which indicates an optimum location of the key structural element, for which the torsional response of the structure is minimized. The location of the key element which minimizes the torsional response of the structure predicted by the analytical solution is verified with reasonable accuracy by the numerical modeling results.

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Role of kinetics on the couplings between fluid flow, deformation and reaction

10.5194/egusphere-egu2020-20626 ◽

2020 ◽

Author(s):

Benjamin Malvoisin ◽

Yury Y. Podladchikov

Keyword(s):

Experimental Data ◽

Fluid Flow ◽

Analytical Solution ◽

Numerical Modelling ◽

Reaction Rate ◽

Slow Slip ◽

Slow Slip Events ◽

Classical Formalism ◽

Flow Deformation

<p>Short timescale processes such as earthquakes, tremors and slow slip events may be influenced by reactions, which are known to proceed rapidly in the presence of water (typically several days). Here, we developed a theoretical framework to introduce the influence of mineralogical reactions on fluid flow and deformation. The classical formalism for dissolution/precipitation reactions is used to consider the influence of the distance from equilibrium and of temperature on the reaction rate and a dependence on porosity is introduced to model the evolution of the reacting surface area during reaction. The thermodynamic admissibility of the derived equations is checked and an analytical solution is derived to test the model. The fitting of experimental data for three reactions typically occurring in metamorphic systems (serpentine dehydration, muscovite dehydration and calcite decarbonation) indicates a systematic faster kinetics on the dehydration side than on the hydration side close from equilibrium. This effect is amplified through the porosity term in the reaction rate. Numerical modelling indicates that this difference in reaction rate close from equilibrium plays a key role in microtextures formation during dehydration in metamorphic systems. The developed model can be used in a wide variety of geological systems where couplings between reaction, deformation and fluid flow have to be considered.</p>

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Chromosomal Lesion Suppression and Removal in Escherichia coli via Linear DNA Degradation

Genetics ◽

10.1093/genetics/163.4.1255 ◽

2003 ◽

Vol 163 (4) ◽

pp. 1255-1271 ◽

Cited By ~ 1

Author(s):

Anabel Miranda ◽

Andrei Kuzminov

Keyword(s):

Dna Degradation ◽

Dna Helicase ◽

Structural Element ◽

E Coli ◽

Linear Dna ◽

Replication Factory ◽

Low Copy Number ◽

Chromosomal Lesion ◽

Recbcd Enzyme

Abstract RecBCD is a DNA helicase/exonuclease implicated in degradation of foreign linear DNA and in RecA-dependent recombinational repair of chromosomal lesions in E. coli. The low viability of recA recBC mutants vs. recA mutants indicates the existence of RecA-independent roles for RecBCD. To distinguish among possible RecA-independent roles of the RecBCD enzyme in replication, repair, and DNA degradation, we introduced wild-type and mutant combinations of the recBCD chromosomal region on a low-copy-number plasmid into a ΔrecA ΔrecBCD mutant and determined the viability of resulting strains. Our results argue against ideas that RecBCD is a structural element in the replication factory or is involved in RecA-independent repair of chromosomal lesions. We found that RecBCD-catalyzed DNA degradation is the only activity important for the recA-independent viability, suggesting that degradation of linear tails of σ-replicating chromosomes could be one of the RecBCD’s roles. However, since the weaker DNA degradation capacity due a combination of the RecBC helicase and ssDNA-specific exonucleases restores viability of the ΔrecA ΔrecBCD mutant to a significant extent, we favor suppression of chromosomal lesions via linear DNA degradation at reversed replication forks as the major RecA-independent role of the RecBCD enzyme.

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