NUMERICAL ANALYSIS OF INEXTENSIONAL, KINEMATICALLY INDETERMINATE ASSEMBLIES

This paper gives a summary of numerical experience of analysis of continuous motion of finite mechanism. The procedure can calculate finite displacement of assemblies composed of rigid bars and pin joints with one degree of freedom. At the beginning of or during the motion, change of degree of freedom, that is bifurcation, and limit point can occur. The algorithm can solve these problems quite easily. We will show the usage of this algorithm in some examples

Comparison of Experimental and Analytical Results on Masonry Infilled RC Frames for Cyclic Lateral Load

The aim of the paper is to give a suggestion to the structural engineers to model masonry  infilled reinforced concrete frames. We made several experiments, and developed some  numerical models. Our previous papers [12–15] we showed three different FEM numerical models (equivalent diagonal strut model, orthotropic surface model and "suggested sophisticated model"), and we made a comparison study between the numerical results and the experimental tests in case of monotonic increasing lateral loads. The experiments were continued with cyclic lateral loads. Using the earlier proposed bi-linear σ - ε curve of the masonry infill and the dierent Young’s moduli to model unloading, which are based on EC6, shows good correlation with the test results, but unfortunately these are not enough precise to calculate the size of the areas under the load-displacement curves, so we obtained wrong  damage parameters. We suggest a new trilinear σ - ε curve. Using this proposed trilinear σ - ε curve of the masonry infill, which is based on EC6, using the "Suggested sophisticated model" with the equivalent struts of the mortar layer shows good correlation with the  experimental test results. Both of the calculated dissipated energies can be calculated in good approximation also before and after the yield point of the infill masonry, thus are already  usable to calculate the damage parameter D, which were determined by energy concept. With the help of the damage parameter D, a comprehensive damage-equivalent curve f (D) is  suggested to calculate the cyclic degradation of the two-storey, one-bay, masonry infilled RC frames

Comparison of experimental and analytical results on masonry infilled RC frames for monotonic increasing lateral load

The aim of the paper is to give a suggestion to the structural engineers to model masonry infilled reinforced concrete frames. We made several experiments, and developed some numerical models. One question is how to model the infill masonry for monotonic increasing lateral load? Three different numerical models were investigated. The simplest model is the equivalent diagonal strut model, where the masonry wall is replaced by a compressed diagonal strut. The next model is the orthotropic surface model, where the masonry wall is taken into account as a membrane or shell surface. Between the RC frame and the boundary of the surface are modelled with special spring and contact elements. The last model is called ``suggested sophisticated model´´, where the bricks and the mortar layers are separately modelled. The brick is taken into consideration as an orthotropic membrane element, while the mortar layers are substituted with short perpendicular and diagonal equivalent compressed struts. We give the necessary data to the material properties. We suggest a bilinear stress-strain relationship that allows reach the experimental results more accurately than the usage of the material values in accordance with Eurocode 6

Different FEM models of reinforced concrete frames stiffened by infill masonry for lateral loads

The aim of the paper is to introduce how to model more accurate masonry infilled reinforced concrete frames with commercially available FEM software. We developed some numerical models. One question is how to model the infill masonry for monotonic increasing lateral load? Three different numerical models were investigated. The simplest model is the equivalent diagonal strut model, where the masonry wall is replaced by a compressed diagonal strut. The next model is the orthotropic surface model, where the masonry wall is taken into account as a membrane or shell surface. Between the RC frame and the boundary of the surface are modelled with special spring and contact elements. The last model is called ``suggested sophisticated model´´, where the bricks and the mortar layers are separately modelled. The brick is taken into consideration as an orthotropic membrane element, while the mortar layers are substituted with short perpendicular and diagonal equivalent compressed struts. In case of all models small displ acements are assumed. We give the necessary data to the material properties in accordance with Eurocode 6. In this paper ``only´´ one numerical example is presented to demonstrate the operability of the different models. In the next step the practical usability and the verification with experiment results of the different models will be presented in another article

Szerkezeti topológia = Structural topology

Numerikus megoldásokat állítottunk elő a körpárok és körhármasok gömbön való legsűrűbb elhelyezésének problémájára, és szimmetria alapú vizsgálatokat végeztünk a gömbi körelhelyezés gráfjának Danzer-féle merevségére vonatkozóan. Egy általunk bevezetett gömbölyűségi kritérium alapján optimális, gömböt közelítő poliédereket konstruáltunk. A szakrális épületeken előforduló csillagpoliéderekre alakmeghatározást és számítógépes rekonstrukciót hajtottunk végre. Konvex testekre vonatkozóan több tételt bizonyítottunk. Meghatároztuk a gömbi és térbeli trivalens szálhálózatok megfeszíthetőségének feltételeit. Gömbi koordinátákban írtuk fel a gömbfelszínre illeszkedő csuklós rúdszerkezetek egyensúlyi és kompatibilitási egyenleteit, és állítottuk elő a szerkezet potenciálfüggvényét. Bebizonyítottuk, hogy egy túlhatározott, háromszorosan szimmetrikus Bricard-mechanizmus esetében bizonyos paraméter értékeknél előfordulhat a kompatibilitási út elágazása. A katasztrófaelméletet kompatibilitási utak elágazásának vizsgálatára alkalmaztuk. Az itt előforduló kettőscsúcs-katasztrófával kapcsolatban egy olyan modellcsaládot elemeztünk, amely a kettőscsúcs-katasztrófa négy alosztályán is keresztülhalad. | Numerical solutions are established to the problem of the densest packing of pairs and triplets of circles on a sphere, and symmetry extended analysis of the Danzerian rigidity of the packing graphs is executed. On the basis of a sphericity criterion introduced by us, polyhedra approximating the sphere are constructed. Shape determination and computer aided reconstruction is done for star polyhedra occurring on sacred buildings. A number of theorems are proved for convex bodies. Criteria of stressability of spherical and spatial trivalent fibre nets are determined. Equilibrium and compatibility equations as well as potential function of bar-and-joint assemblies lying on the surface of a sphere are written with spherical co-ordinates. It is proved that, for certain parameter values, there exists bifurcation of the compatibility path of an overconstrained, threefold symmetric Bricard linkage. Catastrophe theory is applied for investigation of bifurcation of compatibility paths. Concerning double cusp catastrophe, a family of models is analysed, which goes through four subclasses of the double cusp catastrophe

Evans blue fluorescence permits the rapid visualization of non-intact cells in the perilesional rim of cold-injured rat brain

A focal cold lesion-induced injury, i.e., a model of focal vasogenic brain edema, enhances the permeability of the blood-brain barrier and cell membrane in the perilesional rim. However, non-intact cells can be detected, e.g. by markers of apoptosis, only hours or even days after the injury. The early membrane dysfunction allows extravasated serum proteins to enter the injured cells, which can be readily visualized if the plasma albumin was previously bound to fluorescent tracers, such as Evans Blue (EB). The aim of this study was to demonstrate injured cells that take up the EB/albumin conjugate in the perilesional rim. This tracer was administered 3.5 h after the induction of the injury and the animals were sacrificed 30 min later. With an excitation wavelength of 530-550 rim, the EB-positive cells emitted bright-red fluorescence at > 590 rim and were easy to count. No positive cells were observed in the controls. This method provides more information than the classical 2,3,5-triphenyltetrazolium chloride reaction, because it permits an assessment of the density and distribution of cells with non-intact cell membranes in the perilesional area following cerebrocortical injury

The Interacting Rotifer-Biopolymers are Anti- and Disaggregating Agents for Human-Type Beta-Amyloid in vitro

Neurodegeneration-related human-type beta-amyloid 1-42 aggregates (H-Aβ) are one of the biochemical markers and executive molecules in Alzheimer's disease. The exogenic rotifer-specific biopolymer, namely Rotimer, has a protective effect against H-Aβ toxicity on Euchlanis dilatata and Lecane bulla monogonant rotifers. Due to the external particle-dependent secreting activity of these animals, this natural exudate exists in a bound form on the surface of epoxy-metal beads, named as Rotimer Inductor Conglomerate (RIC). In this current work the experiential in vitro molecular interactions between Rotimer and Aβs are presented. The RIC form was uniformly used against H-Aβ aggregation processes in stagogram- and fluorescent-based experiments. These well-known cell-toxic aggregates stably and quickly (only taking a few minutes) bind to RIC. The epoxy beads (as carriers) alone or the scrambled version of H-Aβ (with random amino acid sequence) were the ineffective and inactive negative controls of this experimental system. The RIC has significant interacting, anti-aggregating and disaggregating effects on H-Aβ. To detect these experiments, Bis-ANS and Thioflavin T were applied during amyloid binding, two aggregation-specific functional fluorescent dyes with different molecular characteristics. This newly described empirical interaction of Rotimer with H-Aβ is a potential starting point and source of innovation concerning targeted human- and pharmaceutical applications. Keywords: Aggregation; Biopolymer; Euchlanis dilatata; Monogonant; Rotifer; beta-amyloi

Exceptional in vivo catabolism of neurodegeneration-related aggregates

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