Mapping strain in the footwall of a thrust: Preliminary results from 3D bulk fabric of illite.

The Sigues fold (Aragon, Spain) presents an exceptional outcrop where 1) the footwall is largely exposed, 2) it is constituted of homogenous shales, 3) the strain varies at distance from the emergent thrust, with all steps of cleavage development. The best model to explain the strain distribution is the trishear propagation of a thrust with a P/S ratio of 1.&#160; However, from East to West, the thrust geometry is changing progressively from blind thrust to flat ramp. The topographic surface as well as the position of the emerging part of the thrust determine the geometry of the structure. This is, therefore, a place with variable geometries, which allow us to describe the different geometric stages of the ramp-and-flat model that we are used to find in major orogenic thrusts.To map the strain, we measured the magnetic fabric of hundreds of shale fragments (weighting a few grams) in dozens of localities. The magnetic fabric is governed primarily by illite. Hence, the magnetic fabric represents a 3D view of illite organization, i.e. the matrix of those shales (see Gracia-Puzo et al., EGU, EMRP3.8). The measurement of 3D fabric of illite takes about a minute per fragment and is non-destructive.Magnetic fabric of shale fragments provides three useful parameters, the degree of anisotropy, the shape parameter from oblate to prolate, and the length of the confidence angle of the minimum axis of tensor. We show that all these three parameters are highly sensitive to strain. While each locality provides homogenous results from ~15 fragments (covering few square meters each), it is statistically different from one site to the other, with trends consistent with distance to the main thrust. Assuming rigid rotation of illite particles, we calculate the strain using Eigen values of magnetic fabric tensor.Our preliminary maps shows: 1) that the strain increases considerably (from units to tens in %) when approaching the main thrust, 2) at a distance of more than 1 km, several strain gradients are detected, suggesting that blind thrusts propagate in the footwall. Serial N-S cross-sections are expected to describe the lateral variability on the structure, the deformation accumulated on the footwall and also establishing the portion of the hanging wall which is being affected and the d&#233;collement of the thrust. Our approach is thus promising to map strain in shales from deformed regions, both from natural outcrops, or from boreholes.

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AMS of strained shales fragments: a fast way to quantify the matrix damage

10.5194/egusphere-egu21-6377 ◽

2021 ◽

Author(s):

Francho Gracia Puzo ◽

Charles Aubourg ◽

Antonio Casas Sainz

Keyword(s):

Rock Magnetism ◽

Magnetic Fabric ◽

Magnetic Minerals ◽

Statistical Characterization ◽

Main Thrust ◽

Rock Fragments ◽

Scalar Data ◽

The Matrix ◽

Degree Of Anisotropy

With the objective of mapping strain on the footwall of a thrust in an orogenic context (Leyre thrust, South Pyrenean Range), more than 1500 unoriented shale fragments (0.7-6.2 g) have been collected. Scalar data (degree of anisotropy P and shape parameter T), together with ellipse of confidence of individual axes provide a proxy of strain acquired by shales in the footwall of the main thrust (Saur et al. 2020).Normally, sampling is done by two methods: collecting oriented decimetric hand specimens; or drilling 2.5 cm diameter cylinders. This presents the advantage to deal with oriented samples. However, those techniques are time consuming and it is difficult to collect numerous samples in loose materials such as shales. On the contrary, collecting rock fragments presents the net advantage to provide a much better statistical characterization of the site.All samples belong to the Eocene shaly formations from the Jaca Basin. Rock fragments are mostly fractured according to the bedding and/or cleavage surfaces. We demonstrate that the anisotropy parameters P and T maintain their values, regardless the shape and size of fragments. Rock magnetism indicates that AMS is primarily governed by illite, with little contribution of magnetite. AMS provides therefore a proxy of illite organisation within the matrix.In the footwall of the Sierra de Leyre we have defined up to 7 parallel sampling sections, whose traces are perpendicular to the direction of the main thrust. On average, each section is made up of about 10 sampling sites and about 15 fragments are collected per site, covering a few square meters.We are restricted by the dimensions of AGICO holders (8cm3 for cubes, or 10 cm3 for cylinders). It is possible to use an empty 10 cm3 cylinder, which can be filled with smaller fragments of rock. The automatic rotator allows a fast and precise description of the AMS tensor. We removed from analysis low susceptibility, carbonate-rich samples, that show a higher variety of magnetic minerals. All sites present homogenous results at the site scale, but with significant differences with respect to strain. P and T parameters are very sensitive to strain as illite is the dominant carrier. In addition, the ellipse of confidence of the minimum AMS axis (K3) provides a sensitive proxy to characterize the competition between bedding and cleavage.The comparison between the different sections allows to map the areas of damage linked to the propagation of faults associated with the folds. 5 stages of development of the magnetic fabric allows the detection of damage gradients. The mapping has allowed the identification of hidden faults.&#160;&#160;&#160;&#160;This new approach is very promising, and allows much more detailed samplings in difficult areas, providing more robust statistical description of scalar AMS data. This methodology could be useful for the study of outcrops that are difficult to access, and more interestingly, from borehole cuttings.

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Unravelling heterogeneities in magnetic fabric record of the strain: a combined AMS and ApARM data analysis applied to intraplate shear zones.

10.5194/egusphere-egu21-1481 ◽

2021 ◽

Author(s):

Claudio Robustelli Test ◽

Elena Zanella ◽

Andrea Festa ◽

Francesca Remitti

Keyword(s):

Cluster Analysis ◽

Hanging Wall ◽

Shear Zones ◽

Magnetic Fabric ◽

Plate Boundaries ◽

Thrust Faults ◽

Localized Deformation ◽

Main Thrust ◽

Shear Sense ◽

And Cluster Analysis

Deciphering the stress and strain distribution across plate boundary shear zones is critical to understanding the physical processes involved in the nucleation of megathrust faults and its behaviour. Plate boundaries at shallow depth represent complex and highly deformed zones showing structures from both distributed and localized deformation.As magnetic minerals are sensitive to stress regime, the investigation of the magnetic fabric has proven to be an effective tool in studying faulting processes at intraplate shear zones.Anisotropy of magnetic susceptibility (AMS) provides insights into the preferred orientation of mineral grains and the qualitative relationships between petrofabrics and deformation intensity.We present an approach of combined Contoured Diagram and Cluster Analysis to isolate the contribution of coexisting petrofabrics to the total AMS and evaluating the significance of magnetic fabric clusters.Our results reveal distinct subfabrics with reasonably straightforward correlations with structural data. Specific AMS pattern may be associated to the intensity of the reworking related to tectonic shearing and the structural position within the shear zone (i.e., the proximity to the main thrust faults).Close to the main thrust the magnetic fabric is dominantly oblate with magnetic foliation consistent to the S-C fabric and/or m&#233;lange foliation and the magnetic lineation parallel to the shear sense.Away from the thrust faults the degree of anisotropy as well as the ellipsoids oblateness gradually diminishes. Thus, the presence of subfabrics related to previous tectonic events or less intense deformation (i.e. intersection lineation fabric) became dominant. The discrimination of subfabrics also allowed to unravel the presence of minor thrust plane and qualitatively evaluate the heterogeneous registration of strain (i.e. distributed versus localized deformation).An abrupt change in magnetic ellipsoid shape and parameters is also observed below the basal d&#233;collements showing purely sedimentary magnetic fabric or previous deformation history with minor to absent evidences of shearing in the hanging wall.Then, the integration with anisotropy of magnetic remanence experiments in different coercivity windows (ApARM) allow to separate the contribution of different ferromagnetic subpopulation of grains, constraining the significance of the different magnetic pattern/clusters detected through the AMS analysis.In conclusion, our results show the potential of a combination of density diagrams and cluster analysis validated by ApARM experiments in distinguishing the superposition of deformation events, unravelling strain partitioning/concentration and thus to better understand the geodynamic evolution of subduction-accretion complexes.

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IDENTIFICATION OF ACOUSTIC EMISSION SOURCES IN A POLIMER COMPOSITE MATERIAL UNDER THE CYCLE TENSION LOADING

Vektor nauki Tol yattinskogo gosudarstvennogo universiteta ◽

10.18323/2073-5073-2021-3-19-27 ◽

2021 ◽

pp. 19-27

Author(s):

A. A. Bryansky ◽

◽

O. V. Bashkov ◽

Keyword(s):

Acoustic Emission ◽

Structural Changes ◽

Destructive Testing ◽

Local Formation ◽

Adhesion Failure ◽

Highly Sensitive ◽

The Matrix ◽

Tension Loading ◽

Non Destructive ◽

Ae Signals

The structure of polymer composite materials (PCM) provides high mechanical properties but, at the same time, is highly sensitive to the formation of internal defects. Therefore, when designing, manufacturing products, and assessing their reliability in service, much attention is paid to the methods of non-destructive testing, among which the method of acoustic emission (AE) has proven itself to study structural changes in material under external influence. The paper deals with the identification of typical damages in fiberglass samples made of T11-GVS9 glass fiber cloth and DION 9300 FR binder and tested under cyclic tension using the AE method. In the work, the authors solved the problem of selecting the AE informative parameters and used a clustering method to identify the nature and the formation kinetics of the AE sources. The authors performed clustering using the Kohonen self-organization map (SOM) with the Fourier spectra calculated for the AE signals recorded during cyclic tests. Based on the peak frequencies analysis of the produced clusters, the researchers determined their nature and calculated the periods of critical accumulation. When characterizing the AE sources, the authors used the peak frequencies analysis of the wavelet spectra performed for different levels of decomposition. The authors determined the damage accumulation stages of samples during testing based on own research and research by other authors’ results. The study established that registration of AE signals identified as adhesion failure can be used to identify the onset of the material destruction and characterized the local formation of micro-damages in the matrix and fracture of fibers can be used to predict the destruction of PCM.

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Terahertz characterization of two-dimensional low-conductive layers enabled by metal gratings

Scientific Reports ◽

10.1038/s41598-021-82560-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Prashanth Gopalan ◽

Yunshan Wang ◽

Berardi Sensale-Rodriguez

Keyword(s):

Optical Transmission ◽

Terahertz Spectroscopy ◽

Design Guidelines ◽

Two Dimensional ◽

Highly Sensitive ◽

Transmission Measurements ◽

Metal Gratings ◽

Low Sensitivity ◽

Non Destructive

AbstractWhile terahertz spectroscopy can provide valuable information regarding the charge transport properties in semiconductors, its application for the characterization of low-conductive two-dimensional layers, i.e., σs < < 1 mS, remains elusive. This is primarily due to the low sensitivity of direct transmission measurements to such small sheet conductivity levels. In this work, we discuss harnessing the extraordinary optical transmission through gratings consisting of metallic stripes to characterize such low-conductive two-dimensional layers. We analyze the geometric tradeoffs in these structures and provide physical insights, ultimately leading to general design guidelines for experiments enabling non-contact, non-destructive, highly sensitive characterization of such layers.

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Using bedrock thermochronometer systems to constrain fold-thrust belt geometry and kinematics, insight from the eastern Himalayas, Arunachal Pradesh, India.

10.5194/egusphere-egu21-8977 ◽

2021 ◽

Author(s):

Nadine McQuarrie ◽

Mary Braza

Keyword(s):

Cross Section ◽

Cross Sections ◽

Hanging Wall ◽

Vertical Component ◽

Eastern Himalaya ◽

Thrust Belt ◽

Arunachal Pradesh ◽

Eastern Himalayas ◽

Cross Section Geometry ◽

Geometry And Kinematics

<div> One of the first order questions regarding a cross-section representation through a fold-thrust belt (FTB) is usually &#8220;how unique is this geometrical interpretation of the subsurface?&#8221;&#160; The proposed geometry influences perceptions of inherited structures, decollement horizons, and both rheological and kinematic behavior.&#160; Balanced cross sections were developed as a tool to produce more accurate and thus more predictive geological cross sections.&#160; While balanced cross sections provide models of subsurface geometry that can reproduce the mapped surface geology, they are non-unique, opening the possibility that different geometries and kinematics may be able to satisfy the same set of observations. The most non-unique aspects of cross sections are: (1) the geometry of structures that is not seen at the surface, and (2) the sequence of thrust faulting. &#160;We posit that integrating sequentially restored cross sections with thermokinematic models that calculate the resulting subsurface thermal field and predicted cooling ages of rocks at the surface provides a valuable means to assess the viability of proposed geometry and kinematics. &#160;Mineral cooling ages in compressional settings are the outcome of surface uplift and the resulting focused erosion.&#160; As such they are most sensitive to the vertical component of the kinematic field imparted by ramps and surface breaking faults in sequential reconstructions of FTB. &#160;Because balanced cross sections require that the lengths and locations of hanging-wall and footwall ramps match, they provide a template of the ways in which the location and magnitude of ramps in the basal d&#233;collement have evolved with time. &#160;Arunachal Pradesh in the eastern Himalayas is an ideal place to look at the sensitivity of cooling ages to different cross section geometries and kinematic models. Recent studies from this portion of the Himalayan FTB include both a suite of different cross section geometries and a robust bedrock thermochronology dataset. The multiple published cross-sections differ in the details of geometry, implied amounts of shortening, kinematic history, and thus exhumation pathways. Published cooling ages data show older ages (6-10 Ma AFT, 12-14 Ma ZFT) in the frontal portions of the FTB and significantly younger ages (2-5 Ma AFT, 6-8 Ma ZFT) in the hinterland. These ages are best reproduced with kinematic sequence that involves early forward propagation of the FTB from 14-10 Ma.&#160; The early propagation combined with young hinterland cooling ages require several periods of out-of-sequence faulting. Out-of-sequence faults are concentrated in two windows of time (10-8 Ma and 7-5 Ma) that show systematic northward reactivation of faults.&#160; Quantitative integration of cross section geometry, kinematics and cooling ages require notably more complicated kinematic and exhumation pathways than are typically assumed with a simple in-sequence model of cross section deformation.&#160; While also non-unique, the updated cross section geometry and kinematics highlight components of geometry, deformation and exhumation that must be included in any valid cross section model for this portion of the eastern Himalaya. </div>

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Comparative Isolation of Cilia and Flagella from the Lamellibranch Mollusc, Aequipecten irradians

Journal of Cell Science ◽

10.1242/jcs.12.2.345 ◽

1973 ◽

Vol 12 (2) ◽

pp. 345-367

Author(s):

R. W. LINCK

Keyword(s):

Atpase Activity ◽

Cross Sections ◽

Basal Body ◽

Electron Dense Material ◽

The Matrix ◽

Fine Structures ◽

Dynein Arms ◽

Cilia And Flagella ◽

Triton X ◽

Ciliary Ultrastructure

Gill cilia and sperm flagella from the lamellibranch mollusc Aequipecten irradians were compared with respect to their ultrastructures and adenosinetriphosphatase activities. Cilia were isolated from excised gills using 3 different solutions: twice-concentrated seawater, 10 % ethanol-10 mM CaCl2 and 60% glycerol. In each case deciliation occurs by the severance of the cilium at the junction of the transition zone and the basal body, and in each case the ciliary ultrastructure is maintained. Sperm flagella were purified by mechanical decapitation. Cilia and sperm flagella have similar fine structures, except that the matrix of the cilia contains substantially more electron-dense material than that of flagella. The ATPase activity of purified cilia is approximately 0.09,µmol P1/min/mg protein; that of flagella is 0.13. Ciliary and flagellar axonemes were prepared by repeated extraction of the membranes with 1% Triton X-100. Ciliary axonemes maintain their 9 + 2 cylindrical orientation, whereas flagellar axonemes often appear as opened or fragmented arrays of the 9 + 2 structure, due to the partial breakdown of the flagellar nexin fibres. A-subfibre arms which were obvious in whole organelles are rarely seen in axoneme preparations. Again the ciliary matrix is considerably more amorphous than in flagellar axonemes. The ATPase activities of ciliary and flagellar axonemes are 0.13 and 0.12 µmol P1/min/mg protein respectively; however, activities of ciliary axonemes may vary by a factor of 2, depending on the method of isolation. The difficulty in observing A-subfibre arms in cross-sections of ciliary and flagellar axonemes is discussed in terms of random, non-reinforcing arrangements of the dynein arms.

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Worldline master formulas for the dressed electron propagator. Part 2. On-shell amplitudes

Journal of High Energy Physics ◽

10.1007/jhep01(2022)050 ◽

2022 ◽

Vol 2022 (1) ◽

Author(s):

N. Ahmadiniaz ◽

V. M. Banda Guzmán ◽

F. Bastianelli ◽

O. Corradini ◽

J. P. Edwards ◽

...

Keyword(s):

Cross Sections ◽

Drop Out ◽

Matrix Elements ◽

Fermion Propagator ◽

Particle Path ◽

Path Integral Representation ◽

Fermion Line ◽

Electron Propagator ◽

The Matrix ◽

Standard Linear

Abstract In the first part of this series, we employed the second-order formalism and the “symbol” map to construct a particle path-integral representation of the electron propagator in a background electromagnetic field, suitable for open fermion-line calculations. Its main advantages are the avoidance of long products of Dirac matrices, and its ability to unify whole sets of Feynman diagrams related by permutation of photon legs along the fermion lines. We obtained a Bern-Kosower type master formula for the fermion propagator, dressed with N photons, in terms of the “N-photon kernel,” where this kernel appears also in “subleading” terms involving only N − 1 of the N photons.In this sequel, we focus on the application of the formalism to the calculation of on-shell amplitudes and cross sections. Universal formulas are obtained for the fully polarised matrix elements of the fermion propagator dressed with an arbitrary number of photons, as well as for the corresponding spin-averaged cross sections. A major simplification of the on-shell case is that the subleading terms drop out, but we also pinpoint other, less obvious simplifications.We use integration by parts to achieve manifest transversality of these amplitudes at the integrand level and exploit this property using the spinor helicity technique. We give a simple proof of the vanishing of the matrix element for “all +” photon helicities in the massless case, and find a novel relation between the scalar and spinor spin-averaged cross sections in the massive case. Testing the formalism on the standard linear Compton scattering process, we find that it reproduces the known results with remarkable efficiency. Further applications and generalisations are pointed out.

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Worth a Closer Look: Raman Spectra of Lead-Pipe Scale

Minerals ◽

10.3390/min11101047 ◽

2021 ◽

Vol 11 (10) ◽

pp. 1047

Author(s):

Jill Dill Pasteris ◽

Yeunook Bae ◽

Daniel E. Giammar ◽

Sydney N. Dybing ◽

Claude H. Yoder ◽

...

Keyword(s):

Cross Sections ◽

Water System ◽

Analytical Techniques ◽

Real Time Analysis ◽

Fiber Optic Probes ◽

Lead Pipe ◽

Lead Pipes ◽

Non Destructive

The identification and characterization of lead-bearing and associated minerals in scales on lead pipes are essential to understanding and predicting the mobilization of lead into drinking water. Despite its long-recognized usefulness in the unambiguous identification of crystalline and amorphous solids, distinguishing between polymorphic phases, and rapid and non-destructive analysis on the micrometer spatial scale, the Raman spectroscopy (RS) technique has been applied only occasionally in the analysis of scales in lead service lines (LSLs). This article illustrates multiple applications of RS not just for the identification of phases, but also compositional and structural characterization of scale materials in harvested lead pipes and experimental pipe-loop/recirculation systems. RS is shown to be a sensitive monitor of these characteristics through analyses on cross-sections of lead pipes, raw interior pipe walls, particulates captured in filters, and scrapings from pipes. RS proves to be especially sensitive to the state of crystallinity of scale phases (important to their solubility) and to the specific chemistry of phases precipitated upon the introduction of orthophosphate to the water system. It can be used effectively alone as well as in conjunction with more standard analytical techniques. By means of fiber-optic probes, RS has potential for in situ, real-time analysis within water-filled pipes.

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Magnetic fabric in carbonatic rocks from thrust shear zones

10.5194/egusphere-egu21-1686 ◽

2021 ◽

Author(s):

Sara Satolli ◽

Claudio Robustelli Test ◽

Elena Zanella ◽

Dorota Staneczek ◽

Fernando Calamita ◽

...

Keyword(s):

Cluster Analysis ◽

Pure Shear ◽

Shear Zones ◽

Magnetic Fabric ◽

Structural Deformation ◽

Axis Orientation ◽

Main Thrust ◽

Magnetic Lineation ◽

Magnetic Fabrics ◽

And Cluster Analysis

&#160;The aim of this study is to investigate how structural deformation in shear zones is documented by the anisotropy of magnetic susceptibility (AMS). The study area is located in the Pliocene outer thrust of the Northern Apennines, which involved Cretaceous to Neogene calcareous and marly rocks. Here, brittle-ductile tectonites show different characteristics along two differently oriented thrust ramps: the NNE-SSW-trending oblique thrust ramp is characterized by the presence of S tectonites, while the NW-SE-trending frontal ramp is characterized by the presence of SC tectonites.Samples for AMS fabric investigation were collected on shear zones from three sectors of the belt, at different distance from the main thrust to detect possible magnetic fabric variations. The three study area are characterized by different combinations of simple and pure shear, thus different degree of non-coaxiality, which has been quantified through the vorticity number Wk.Specimens were measured with an AGICO KLY-3 Kappabridge at the CIMaN-ALP Laboratory (Italy) on 15 different directions mode. Only measurements with all three F-statistics of the anisotropy tests higher than 5 were accepted as reliable. Moreover, outliers characterized by &#177; 2&#963; difference with respect to the mean value of AMS scalar parameters were excluded from further analysis. In order to distinguish groups of specimens affected by different sedimentary or tectonic processes, we identified clusters of AMS scalar parameters; when clusters were not defined by these parameters, we applied a combination of contouring and cluster analysis on each principal axis to identify different subfabrics.The magnetic fabric revealed straightforward correlations with structural data and specific changes of AMS axis orientation depending upon the increasing of deformation (lower vorticity number) and proximity to the main thrust. Similar evolution was detected in different deformation regimes. Overall, the magnetic fabric is more sensitive to the simple shear deformation, as the magnetic lineation tends to parallelize mostly with the computed slip vector; however in pure-shear dominated regimes, the magnetic lineation becomes parallel to the transport direction when the deformation is really intense (sites at less than 15-30 cm from the thrust plane).The applied combination of density diagrams and cluster analysis on AMS data successfully allowed discriminating subfabrics related to different events, and shows a great potential to unravel mixed sedimentary and/or tectonic features in magnetic fabrics.

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STIFFNESS OF REINFORCED CONCRETE STRUCTURES UNDER BENDING WITH TRANSVERSE AND LONGITUDINAL FORCES

Building and reconstruction ◽

10.33979/2073-7416-2021-98-6-5-19 ◽

2021 ◽

Vol 98 (6) ◽

pp. 5-19

Author(s):

VL.I. KOLCHUNOV ◽

◽

O.I. AL-HASHIMI ◽

M.V. PROTCHENKO ◽

◽

...

Keyword(s):

Reinforced Concrete ◽

Cross Sections ◽

Concrete Structures ◽

Bending Moment ◽

Reinforced Concrete Structures ◽

The Matrix ◽

Local Shear ◽

The Difference ◽

Inclined Cracks ◽

Opening Width

The authors developed a model for single reinforced concrete strips in block wedge and arches between inclined cracks and approximated rectangular cross-sections using small squares in matrix elements. From the analysis of the works of N.I. Karpenko and S.N. Karpenko the "nagel" forces in the longitudinal tensile reinforcement and crack slip , as a function of the opening width and concrete deformations in relation to the cosine of the angle . The experimental " nagel " forces and crack slip dependences for the connection between and in the form of an exponent for the reinforcement deformations and spacing are determined. The forces have been calculated for two to three cross-sections (single composite strips) of reinforced concrete structures. On the bases of accepted hypothesis, a new effect of reinforced concrete and a joint modulus in a strip of composite single local shear zone for the difference of mean relative linear and angular deformations of mutual displacements of concrete (or reinforcement) are developed. The hypothesis allows one to reduce the order of the system of differential equations of Rzhanitsyn and to obtain in each joint the total angular deformations of concrete and the "nagel" effect of reinforcement. The curvature of the composite bars has a relationship from the total bending moment of the bars to the sum of the rigidities. The stiffness physical characteristics of the matrix from the compressed concrete area and the working reinforcement are obtained in a system of equations of equilibrium and deformation, as well as physical equations.

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