scholarly journals Tensile Capacity of Adhesive Anchors in Damaged Masonry

2021 ◽  
Vol 11 (21) ◽  
pp. 10135
Author(s):  
Sara Cattaneo ◽  
Navid Vafa
Keyword(s):  
Tensile Strength ◽  
Main Parameter ◽  
Initial Conditions ◽  
Seismic Events ◽  
Seismic Action ◽  
Critical Areas ◽  
Experimental Campaign ◽  
Adhesive Anchors ◽  
Ultimate Resistance

In Europe, the qualification of injection anchors in masonry under static and quasi-static actions is based on an assessment of tests performed in undamaged masonry. Nevertheless, in seismic prone countries like Italy the influences deriving from earthquake actions cannot be disregarded. Masonry elements are very sensitive to cyclic/seismic action and research on the behavior of anchors in damaged masonry is rather limited. The paper presents the results of an experimental campaign aimed at evaluating the residual tensile strength of adhesive anchors installed into undamaged walls that were subsequently subjected to cyclic in-plane loading to simulate seismic actions before. Consequently, the anchors experienced different stresses depending on their location within the walls. Overall, 29 tests were performed with anchors placed both, in undamaged and damaged areas. The results showed that there is a correlation between residual tensile strength and masonry initial conditions, and therefore the installation of anchors in masonry elements should be carefully planned avoiding areas that could be heavily damaged during seismic events or considering redundant connections in critical areas. In particular, it seems that the width of the crack (created by cyclic actions) that passes nearby/into the anchor borehole is the main parameter that affects the ultimate resistance of the anchors.

CHAOTIC ANALYSIS OF A TIME SERIES COMPOSED OF SEISMIC EVENTS RECORDED IN JAPAN

1994 ◽  
Vol 04 (01) ◽  
pp. 87-98 ◽  
Author(s):  
G.P. PAVLOS ◽  
L. KARAKATSANIS ◽  
J.B. LATOUSSAKIS ◽  
D. DIALETIS ◽  
G. PAPAIOANNOU
Keyword(s):  
Time Series ◽  
Lyapunov Exponent ◽  
Initial Conditions ◽  
Low Frequency ◽  
Underlying Mechanism ◽  
Largest Lyapunov Exponent ◽  
Seismic Events ◽  
Earthquake Dynamics ◽  
The Largest Lyapunov Exponent ◽  
Low Dimensional

A chaotic analysis approach was applied to an earthquake time series recorded in the Japanese area in order to test the assumption that the earthquake process could be the manifestation of a chaotic low dimensional process. For the study of the seismicity we have used a time series consisting of time differences between two consecutive seismic events with magnitudes greater than 2.6. The results of our study show that the underlying mechanism, as expressed by the time series, can be described by low dimensional chaotic dynamics. The power spectrum of the time series shows a power law profile with two slopes, α=1.4 in the low frequency and α=0.05 in the high frequency regions, while the slopes of the correlation integrals show an apparent plateau at the scaling region, which saturates at the value D≈3.2. The largest Lyapunov exponent was found to be ≈0.9. The positive value of the largest Lyapunov exponent reveals strong sensitivity to initial conditions of the supposed earthquake dynamics.

scholarly journals Grain Refinement and Improved Mechanical Properties of EUROFER97 by Thermo-Mechanical Treatments

2021 ◽  
Vol 11 (22) ◽  
pp. 10598
Author(s):  
Giulia Stornelli ◽  
Andrea Di Schino ◽  
Silvia Mancini ◽  
Roberto Montanari ◽  
Claudio Testani ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Tensile Strength ◽  
Heat Treatments ◽  
Treatment Temperature ◽  
Steel Plates ◽  
Experimental Campaign ◽  
Different Temperatures ◽  
Fusion Applications ◽  
Cold Rolled

EUROFER97 steel plates for nuclear fusion applications are usually manufactured by hot rolling and subsequent heat treatments: (1) austenitization at 980 °C for 30 min, (2) rapid cooling and (3) tempering at 760 °C for 90 min. An extended experimental campaign was carried out with the scope of improving the strength of the steel without a loss of ductility. Forty groups of samples were prepared by combining cold rolling with five cold reduction ratios (20, 40, 50, 60 and 80%) and heat treatments at eight different temperatures in the range 400–750 °C (steps of 50 °C). This work reports preliminary results regarding the microstructure and mechanical properties of all the cold-rolled samples and the effects of heat treatments on the samples deformed with the greater CR ratio (80%). The strength of deformed samples decreased as heat treatment temperature increased and the change was more pronounced in the samples cold-rolled with greater CR ratios. After heat treatments at temperature up to 600 °C yield stress (YS) and ultimate tensile strength (UTS) of samples deformed with CR ratio of 80% were significantly larger than those of standard EUROFER97 but ductility was lower. On the contrary, the treatment at 650 °C produced a fully recrystallized structure with sub-micrometric grains which guarantees higher strength and comparable ductility. The work demonstrated that EUROFER97 steel can be strengthened without compromising its ductility; the most effective process parameters will be identified by completing the analyses on all the prepared samples.

scholarly journals Modelling and Evaluation of the Seismic Capacity of Typical Brick URM Buildings of the Historical Center of Cuenca- Ecuador

2021 ◽  
Vol 1203 (3) ◽  
pp. 032123
Author(s):  
José Calderón-Brito ◽  
Juan Jiménez-Pacheco
Keyword(s):  
Seismic Vulnerability ◽  
Lateral Displacement ◽  
Pushover Analysis ◽  
Brick Masonry ◽  
Seismic Events ◽  
Seismic Action ◽  
Seismic Capacity ◽  
Historic Center ◽  
Built Heritage ◽  
The City

Abstract The Historic Center of Cuenca (HCC) is located in the southern region of Ecuador. It is well known that our country is located on the so-called belt of fire of the Pacific Ocean, this area is characterized by having generated the most important seismic events in the history of mankind. More specifically, there are records that show that in the last 200 years the city of Cuenca has been exposed to earthquakes that have produced moderate to severe damage. These reasons make it possible to establish that the city of Cuenca and specifically its historic center could present important problems in the face of significant seismic events. Most of the buildings in the HCC date back to the middle of the 20th century and have used unreinforced brick masonry (brick-URM) to build their walls. This work is part of the Seismic Vulnerability Project: Seismic Damage Scenarios of the Built Heritage of the Historic Center of Cuenca. In the context of this vulnerability project, the objective of this work was to establish a family of pushover curves for three unreinforced brick masonry buildings typical of the HCC, based on a parametric pushover analysis. The definition of the typical buildings was based on an extensive work of architectural and geometric characterization of the traditional built heritage of HCC. On the basis of focusing the study on two-story buildings (the most common), the size of the floor area of the buildings (small, medium and large area) was assumed as a base parameter. Based on an analysis of the variability of different geometric and mechanical characteristics, and in order to study their influence on the pushover curves of the three typical brick URM buildings, the following study parameters were defined: 1) compressive strength of brick masonry, 2) lateral displacement capacity of brick-URM elements, 3) wall thickness. The pushover analysis was carried out with the Ruaumoko program. The model of the buildings responds to an equivalent portal frame macro-model scheme that has been formulated and validated by the authors of this paper. In order to consider the effects of the flexible floor on the dynamic response of this type of structures, a lateral load pattern that takes into account the contribution of higher order modes of vibration will be used in pushover analysis. The results will be discussed in terms of the incidence of the variability of the study parameters on the basic characteristics of the pushover curves. These results will be an essential input for the next stage of the project consisting of damage estimation for different levels of seismic action expected in the city.

scholarly journals Deep-seated gravitational slope deformation scaling on Mars and Earth: same fate for different initial conditions and structural evolutions

2018 ◽  
Author(s):  
Olga Kromuszczyńska ◽  
Daniel Mège ◽  
Krzysztof Dębniak ◽  
Joanna Gurgurewicz ◽  
Magdalena Makowska ◽  
...  
Keyword(s):  
Finite Strain ◽  
Initial Conditions ◽  
Structural Evolution ◽  
Slope Deformation ◽  
Width Ratio ◽  
Seismic Events ◽  
Tatra Mountains ◽  
Valles Marineris ◽  
Fault Scarps ◽  
The Tatra Mountains

Abstract. Some of the most spectacular instances of deep-seated gravitational slope deformation (DSGSD) are found on Mars in the Valles Marineris region. They provide an excellent opportunity to study DSGSD phenomenology using a scaling approach. The topography of selected DSGSD scarps in Valles Marineris and in the Tatra Mountains is investigated after their likely similar postglacial origin is established. The deformed Martian ridges are larger than the deformed terrestrial ridges by one to two orders, with however a similar height-to-width ratio, ~ 0.24. The measured finite strain of the Valles Marineris ridges is 3 times larger than in the Tatra Mountains, suggesting that starting from two different initial conditions, with steeper slopes in Valles Marineris, the final ridge geometry is now similar. Because DSGSD is expected to be now inactive in both regions, their comparison suggests that whatever the initial ridge morphology, DSGSD proceeds until a mature profile is attained. On both planets, strain is distributed over the same number (~ 5) of major scarps; fault displacements are therefore much larger on Mars. The large offsets make necessary reactivation of the DSGSD fault scarps in Valles Marineris, whereas single seismic events would be enough to generate DSGSD fault scarps in the Tatra Mountains. The required longer activity of the Martian faults may be correlated with a long succession of climate cycles generated by the unstable Mars obliquity. In spite of similar global geometry today, the studied ridges on Mars and Earth affected by DSGSD did not start from similar initial conditions and did not follow the same structural evolution.

scholarly journals Deep-seated gravitational slope deformation scaling on Mars and Earth: same fate for different initial conditions and structural evolutions

2019 ◽  
Vol 7 (2) ◽  
pp. 361-376 ◽  
Author(s):  
Olga Kromuszczyńska ◽  
Daniel Mège ◽  
Krzysztof Dębniak ◽  
Joanna Gurgurewicz ◽  
Magdalena Makowska ◽  
...  
Keyword(s):  
Initial Conditions ◽  
Slope Deformation ◽  
Width Ratio ◽  
Seismic Events ◽  
Tatra Mountains ◽  
Valles Marineris ◽  
Excellent Opportunity ◽  
Climate Cycles ◽  
Fault Scarps ◽  
The Tatra Mountains

Abstract. Some of the most spectacular instances of deep-seated gravitational slope deformation (DSGSD) are found on Mars in the Valles Marineris region. They provide an excellent opportunity to study DSGSD phenomenology using a scaling approach. The topography of selected DSGSD scarps in Valles Marineris and in the Tatra Mountains is investigated after their likely similar postglacial origin is established. The deformed Martian ridges are larger than the deformed terrestrial ridges by 1 to 2 orders of magnitude with, however, a similar height-to-width ratio of ∼0.24. The measured horizontal spreading perpendicular to the ridges is proportionally 1.8 to 2.6 times larger for the Valles Marineris ridges than the Tatra Mountains and vertically 2.9 to 5.1 times larger, suggesting that starting from two different initial conditions, with steeper slopes in Valles Marineris, the final ridge geometry is now similar. Because DSGSD is expected to now be inactive in both regions, their comparison suggests that whatever the initial ridge morphology, DSGSD proceeds until a mature profile is attained. Fault displacements are therefore much larger on Mars. The large offsets imply reactivation of the DSGSD fault scarps in Valles Marineris, whereas single seismic events would be enough to generate DSGSD fault scarps in the Tatra Mountains. The required longer activity of the Martian faults may be correlated with a long succession of climate cycles generated by the unstable Martian obliquity.

scholarly journals Full-Scale Experimental Investigation of the Interaction between Trains and Tunnels

2020 ◽  
Vol 10 (20) ◽  
pp. 7189
Author(s):  
Claudio Somaschini ◽  
Tommaso Argentini ◽  
Elia Brambilla ◽  
Daniele Rocchi ◽  
Paolo Schito ◽  
...  
Keyword(s):  
Pressure Wave ◽  
Initial Conditions ◽  
Experimental Tests ◽  
Full Scale ◽  
Aerodynamic Loads ◽  
Fundamental Parameters ◽  
Test Conditions ◽  
Experimental Campaign ◽  
European Standards ◽  
Scale Data

This works focuses on a series of experimental tests carried out to investigate overpressures in tunnels due to train crossings. Although the above-mentioned topic is well known and also defined in European standards, in the literature full-scale data are lacking, which are useful to validate the numerical codes required in the certification process and are used in train structural dimensioning. In this respect, an extensive full-scale experimental campaign was planned for observing as many test conditions as possible, such as single passages of different trains, two train crossing, different tests speed, and different tunnel characteristics. In detail, the understanding of the pressure wave generation and transmission is deeply enhanced by studying the pressure evolution both on board and at trackside, considering both single train passages or two trains crossings and having the possibility to compare aerodynamic loads on sealed and unsealed trains. Furthermore, the position of sensors, the speed of the train, and the initial conditions within the tunnel have been proven to be fundamental parameters for properly estimating the pressure loads on trains.

scholarly journals On Inner Regularity of Solutions of Two-Dimensional Zakharov-Kuznetsov Equation

2019 ◽  
Vol 65 (3) ◽  
pp. 513-546
Author(s):  
A V Faminskii
Keyword(s):  
Initial Function ◽  
Main Parameter ◽  
Initial Conditions ◽  
Initial Boundary ◽  
Regularity Of Solutions ◽  
Initial Boundary Value Problems ◽  
Spatial Variables ◽  
Regularity Of Weak Solutions ◽  
Different Types ◽  
Initial Boundary Value

In this paper, we consider questions of inner regularity of weak solutions of initial-boundary value problems for the Zakharov-Kuznetsov equation with two spatial variables. The initial function is assumed to be irregular, and the main parameter governing the regularity is the decay rate of the initial function at infinity. The main results of the paper are obtained for the problem on a semistrip. In this problem, different types of initial conditions (e. g., Dirichlet or Neumann conditions) influence the inner regularity. We also give a survey of earlier results for other types of areas: a plane, a half-plane, and a strip.

Numerical study of fault sliding under fluid injection

2021 ◽  
Author(s):  
Vasily Riga ◽  
Turuntaev Sergey
Keyword(s):  
Initial Conditions ◽  
Numerical Study ◽  
Fluid Injection ◽  
Seismic Events ◽  
Friction Behavior ◽  
Fault Behavior ◽  
Single Well ◽  
Sliding Dynamics ◽  
System Geometry ◽  
Two Parameter

<p>Seismicity associated with fluid injection into the subsurface is one of the most important issues worldwide. Fluid injection into or near a fault could lead to the fault sliding and to moderate or even hazardous seismic events. In the presented research, we study the single fault behavior under action of a single well injection near the fault. Various cases of initial conditions, system geometry, and friction properties of the fault are considered. To describe the friction on the fault we use two-parameter rate-and-state law. The fault has zones characterized by velocity-weakening and velocity-strengthening friction behavior. We analyze how location and size of the velocity-weakening zone and parameters of the friction law influence the fault sliding dynamics. We also consider how the fault sliding is changed when taking into account the rock poroelastic effects. As the result, we get conditions that are favorable for the occurrence of noticeable seismicity.</p>

Phase Transformations in Ti-7w/oMo-3w/oMe Alloy

1974 ◽  
Vol 32 ◽  
pp. 514-515
Author(s):  
S. Fujishiro
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Transmission Electron Microscopy ◽  
Tensile Strength ◽  
Mechanical Processing ◽  
Ray Method ◽  
X Ray ◽  
Transmission Electron ◽  
Water Quench ◽  
Alpha Beta

The mechanical properties of three titanium alloys (Ti-7Mo-3Al, Ti-7Mo- 3Cu and Ti-7Mo-3Ta) were evaluated as function of: 1) Solutionizing in the beta field and aging, 2) Thermal Mechanical Processing in the beta field and aging, 3) Solutionizing in the alpha + beta field and aging. The samples were isothermally aged in the temperature range 300° to 700*C for 4 to 24 hours, followed by a water quench. Transmission electron microscopy and X-ray method were used to identify the phase formed. All three alloys solutionized at 1050°C (beta field) transformed to martensitic alpha (alpha prime) upon being water quenched. Despite this heavily strained alpha prime, which is characterized by microtwins the tensile strength of the as-quenched alloys is relatively low and the elongation is as high as 30%.

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