scholarly journals Experimental Studies of Reduction Effects on Seismic Stresses in the Cross Section of Shield Tunnels.

1994 ◽  
pp. 107-116
Author(s):  
Mikio Takeuchi ◽  
Yoshiaki Idota ◽  
Tadashi Takahashi ◽  
Takashi Misawa

The work of multilayer glass structures for central and eccentric compression and bending are considered. The substantiation of the chosen research topic is made. The description and features of laminated glass for the structures investigated, their characteristics are presented. The analysis of the results obtained when testing for compression, compression with bending, simple bending of models of columns, beams, samples of laminated glass was made. Overview of the types and nature of destruction of the models are presented, diagrams of material operation are constructed, average values of the resistance of the cross-sections of samples are obtained, the table of destructive loads is generated. The need for development of a set of rules and guidelines for the design of glass structures, including laminated glass, for bearing elements, as well as standards for testing, rules for assessing the strength, stiffness, crack resistance and methods for determining the strength of control samples is emphasized. It is established that the strength properties of glass depend on the type of applied load and vary widely, and significantly lower than the corresponding normative values of the strength of heat-strengthened glass. The effect of the connecting polymeric material and manufacturing technology of laminated glass on the strength of the structure is also shown. The experimental values of the elastic modulus are different in different directions of the cross section and in the direction perpendicular to the glass layers are two times less than along the glass layers.


Author(s):  
Vicente Albero ◽  
Ana Espinós ◽  
Enrique Serra ◽  
Manuel L. Romero ◽  
Antonio Hospitaler

Steel-concrete composite beams embedded in floors (slim-floors) offer various advantages such as the floor thickness reduction or the ease of installation of under-floor technical equipment. However, this typology presents important differences in terms of thermal behaviour, as compared to other composite beams, when exposed to elevated temperatures. These differences are due to their special configuration, being totally contained within the concrete floor depth. Moreover, the current European fire design code for composite steel-concrete structures (EN 1994-1-2) does not provide any simplified thermal model to evaluate the temperature evolution of each slim-floor part during a fire. Additionally, only a few experimental studies can be found which may help understand the thermal behaviour of these composite beams. This paper presents an experimental investigation on the thermal behaviour of slim-floor beams. Electrical radiative panels were used in the test setup to produce the thermal heating. The thermal gap between the lower flange of the steel profile and the bottom steel plate was studied, being found to be one of the most influential elements over the cross-section temperature gradient. The experimental campaign was developed by varying the cross-section configuration in order to evaluate the influence of this parameter over the slim-floor thermal behavior. Finally, the experiments carried out were used to develop and calibrate a finite element thermal model which may help in further research on the thermal behaviour of slim-floor composite beams.


2019 ◽  
Vol 97 (11) ◽  
pp. 1206-1209
Author(s):  
Ezgi Tantoğlu ◽  
Nalan Özkan ◽  
R. Taygun Güray

There are 35 proton-rich isotopes between 74Se and 196Hg that cannot be synthesized through neutron captures and β− decays (s- and r-processes). A third process is therefore required for the production of these nuclei, the so-called p-process. The abundance and the origin of the p-nuclei are still not fully understood even though significant experimental and theoretical efforts in astrophysical modeling have been expended in the last two decades. The experimental studies with the activation method to measure cross sections of the relevant reactions have some limitations: the reaction product must be radioactive, should have an appropriate half-life, and its decay should be followed by proper γ-radiations. If the cross section cannot be calculated with the radiation followed by the first beta decay of the product, it can be measured using the second beta decay as an alternative method. In this study, the method and candidate reactions for the cross-section measurements via the second beta decay of the reaction product using the activation method are discussed.


2020 ◽  
pp. 93-101
Author(s):  
Serhii Bondarenko ◽  
Olexandr Grydin ◽  
Yaroslav Frolov ◽  
Olga Kuzmina ◽  
Oleksandr Bobukh

Specialists of metallurgy and mechanical engineering are intensively working at materials with controlled properties. In fact, at this stage we are already talking about the design of new materials for the specific tasks of the industry. One of the ways to achieve the regulated mechanical properties of metal products is to use the influence of plastic deformation with its different parameters in individual sections of the deformable material. In this study, we studied the effect of cold rolling on the properties of a strip of aluminum alloy EN AW-1050 with artificially created differences in the deformation parameters in different parts of the cross section of the profile. For this, a pre-shaped sample was prepared by conducting joint cold rolling of a strip of the specified material 420 mm long, 180 mm wide and 2.9 mm thick with a steel profiling tape 80 mm wide and 2 mm thick superimposed on it (length of an aluminum strip and steel profiling tape are the same). As a result of joint deformation, the steel strip rolled into the base metal and changed the geometry of the cross section and the properties of the obtained strip. Next, the obtained strip was subjected to heat treatment and rolled in a duo mill. After rolling, thin samples were made from fabricated flat strips to assess mechanical properties, in particular tensile tests were performed according to ISO 6892-1: 2009 and Brinell hardness tests were performed according to ISO 6506-1: 2014. Experimental studies of cold rolling of strips with profiled cross section of aluminum alloy EN AW-1050 were carried out. The possibility of forming heterogeneous properties in a flat aluminum strip by cold plastic deformation is shown and the maximum average values of the increase in the main indicators of mechanical properties on individual elements of the strip are determined. The maximum difference between the mechanical properties of the thick and thin elements of the profiled strip is observed in the hardness index and reaches 37.5%. The maximum obtained average value of the increase in yield strength and tensile strength is 26% and 18%, which is achieved with true deformation of the thick element of the profiled strip 0.165 and 0.234.


2019 ◽  
Vol 87 (3) ◽  
Author(s):  
Zheng Xu ◽  
Zhichao Fan ◽  
Yanyang Zi ◽  
Yihui Zhang ◽  
Yonggang Huang

Abstract Mechanically guided three-dimensional (3D) assembly based on the controlled buckling of pre-designed 2D thin-film precursors provides deterministic routes to complex 3D mesostructures in diverse functional materials, with access to a broad range of material types and length scales. Existing mechanics studies on this topic mainly focus on the forward problem that aims at predicting the configurations of assembled 3D structures, especially ribbon-shaped structures, given the configuration of initial 2D precursor and loading magnitude. The inverse design problem that maps the target 3D structure onto an unknown 2D precursor in the context of a prescribed loading method is essential for practical applications, but remains a challenge. This paper proposes a systematic optimization method to solve the inverse design of ribbon-type 3D geometries assembled through the buckling-guided approach. In addition to the torsional angle of the cross section, this method introduces the non-uniform width distribution of the initial ribbon structure and the loading mode as additional design variables, which can significantly enhance the optimization accuracy for reproducing the desired 3D centroid line of the target ribbon. Extension of this method allows the inverse design of entire 3D ribbon configurations with specific geometries, taking into account both the centroid line and the torsion for the cross section. Computational and experimental studies over a variety of elaborate examples, encompassing both the single-ribbon and ribbon-framework structures, demonstrate the effectiveness and applicability of the developed method.


2021 ◽  
Vol 11 (3) ◽  
pp. 26-31
Author(s):  
Igor K. RODIONOV ◽  
Evgeniy G. SAFRONOV

The results of the survey of steel trusses covering six industrial buildings are presented. In particular, the presence of various forms of defects of compressed rods was revealed: general bends in the plane and out of the plane of the truss, local perishes of the shelves - grinding and grinding. The necessity of strengthening the rods for further operation of the structures is determined. The proposed technical solutions for strengthening deformed rods are presented. When developing technical solutions, we tried to achieve, if possible, compensation for the damaged part of the cross-section (for locally damaged rods) and bringing the axis of the repaired rod to the design position (for rods with common bends). To confi rm the eff ectiveness of the proposed solutions, experimental studies were conducted. A brief analysis of the results is given.


2019 ◽  
Author(s):  
Yuping Guo

The anomalous magnetic momentum of the muon, a_{\mu}aμ, has been measured and calculated with a precision up to ~0.50.5 ppm, but there is a 3 to 4 standard deviations between these two values. The uncertainty in the calculation is dominated by the hadronic part, including the hadronic vacuum polarization and the hadronic light-by-light. The meson transition form factors and the helicity amplitudes can be used as input or constraint to the calculation of the hadronic light-by-light contribution. Latest experimental studies of the transition form factors of \pi^{0}π0, \etaη, and \eta^{\prime}η′ and the cross-section of \gamma\gamma^*\to\pi^+\pi^-γγ*→π+π− from e^{+}e^{-}e+e− collider are presented.


2021 ◽  
Vol 64 (10) ◽  
pp. 712-720
Author(s):  
A. A. Umanskii ◽  
A. B. Yur'ev ◽  
L. V. Dumova

Experimental studies carried out in the conditions of a laboratory rolling mill have determined the regularities of the processes of metal flow and roll-out defects of billets during deformation in roughing stands of a universal rail and structural mill. In relation to the box size and gauges types "lying trapeze" and "trapeze", we have determined a significant irregularity of drawing coefficients of the surface layers by roll length and width, as well as the irregularity of drawing in the cross-section of the roll during rolling. It is shown that during deformation the surface zones adjacent to the ends of the roll are subjected to the greatest drawing, and dependence of irregularity of the drawing coefficients over the cross-section of the roll on the shape of the deformation zone has a distinct power-law character. We have established a significant effect of the drawing coefficient, as well as the location and spatial orientation of the billet defects, while the geometric dimensions of the defects don't have such influence on their roll-out coefficients. According to the obtained data, the defects located on the rolling edges are rolled out most intensively both in depth and width, and the transverse defects are rolled out the least intensively. At the same time, the rollability of any defects increases with the growth of drawing coefficient. It is determined that near the side edges of the roll there is an increase in the width (disclosure) of transverse and inclined defects relative to the rolling axis, as well as the disclosure of defects occurs at the end sections of the roll in relation to longitudinal defects. For internal defects, it was found that, similar to surface defects, an increase in the drawing coefficient during rolling contributes to an increase in their roll-out, while the rollout coefficient of internal defects in absolute value is significantly lower than this indicator for surface defects. It was determined that the minimum roll-out coefficient of internal defects occurs when they are located in the core of the sample, while the roll-out coefficient of such defects increases linearly when moving towards the roll surface. The influence of the location, spatial orientation, and drawing coefficient on the rollability of surface and internal defects is generalized in the form of regression equations. It makes it possible to use them in practice to predict the quality of finished rolled metal when changing rolling modes.


Author(s):  
M.A. Yakymchuk ◽  
◽  
I.M. Korchagin ◽  

The results of a reconnaissance survey of local zones within the oil site of the Uzon volcano, Bogachevskoye oil field, and site of the explosive crater in Yamal are presented. Experimental studies using the direct-prospecting technology of a frequency-resonance processing and interpretation of satellite images and photographs are carried out to study the features of the deep structures of the survey areas. The results of instrumental measurements indicate that all survey sites are located above volcanoes of sedimentary rocks, within which the synthesis of oil, condensate and gas is almost always carried out at the 57 km border. In the contours of HC-generating volcanoes, there are deep channels through which oil, condensate, and gas migrate to the upper horizons of the cross-section and can replenish the already formed deposits in HC fields. In the absence of reliable seals over such channels, oil, condensate, and gas can migrate to the surface, and gas further enters the atmosphere. Measurements within a relatively large area around the Uzon volcano confirmed the presence of all previously identified types of volcanoes. These are volcanoes filled with: 1) salt; 2) sedimentary rocks of 1-6 groups; 3) limestones; 4) dolomites; 5) marls; 6) siliceous rocks; 7) granites; 8) basalts; 9) ultramafic rocks; 10) kimberlites. Additional evidence obtained by instrumental measurements in favor of the deep (abiogenic) genesis of oil, condensate, and gas is of fundamental importance. Numerous facts of fixing the signals from oil, condensate, and gas at the boundary of their synthesis 57 km within the survey areas and in other regions of the world allow us to state that abiogenic methane is migrating into Earth’s atmosphere in colossal volumes! Local zones of the gas migration into the atmosphere can serve as indicators of the activity of volcanoes in which hydrocarbons are synthesized. In these cases, drilling wells in the areas of the location of deep channels for the migration of abiogenic hydrocarbons to the upper horizons of the cross-section may be associated with great risks — with emergency situations during the drilling.


Author(s):  
M.A. Yakymchuk ◽  
◽  
I.M. Korchagin ◽  

The results of a reconnaissance survey of local areas, where a number of oil slicks are located in various regions of the Gulf of Mexico, are presented. Experimental studies using the direct-prospecting technology of frequency- resonance processing and the interpretation of satellite and photo images were carried out in order to study the features of the deep structure in the areas, where slicks are located. The results of instrumental measurements indicate that all nine survey sites in the Gulf are located above volcanoes, within which the synthesis of oil, condensate, and gas is carried out at the conditional border of 57 km. In the contours of such volcanoes, there are deep channels through which oil, condensate, and gas migrate to the upper horizons of the cross-section and can replenish the already formed deposits in hydrocarbon fields. In the absence of reliable seals over such channels, oil, condensate, and gas can migrate into the water column, and gas further into the atmosphere. During this migration, gas seeps are formed on the seabed and oil slicks on the water surface. The measurements confirmed the presence of all previously established types of volcanoes, in which conditions for the hydrocarbon synthesis exist at a depth of 57 km. These are volcanoes filled with 1) salt, 2) sedimentary rocks, 3) limestones, 4) granites, and 5) ultramafic rocks. Studies at the site near the emergency well indicate that there are a significant number of volcanoes in the Gulf, within which there are no conditions for the synthesis of hydrocarbons and amber. These are volcanoes filled with 1) dolomites, 2) marls, 3) siliceous rocks, as well as 4) basalts and 5) kimberlites. The additional evidence is obtained by instrumental measurements in favor of the deep (abiogenic) genesis of oil, condensate, and gas is of fundamental importance. Numerous facts of fixing the signals from oil, condensate, and gas at the conditional boundary of their synthesis of 57 km in the Gulf of Mexico and in other regions of the world allow us to make an assumption about the migration of abiogenic methane into the Earth’s atmosphere in colossal volumes! Methane seeps and oil slicks can serve as indicators of the activity of volcanoes in which hydrocarbons are synthesized. In these cases, drilling wells in the areas of the location of deep channels of the migration of abiogenic hydrocarbons to the upper horizons of the cross-section may be associated with great risks — with emergency situations during drilling.


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