scholarly journals PREDICTION OF SHEAR RESISTANCE FACTOR IN FLAT SLABS DESIGN USING CRITICAL PERIMETER OF SUPPORTING COLUMNS

2016 ◽  
Vol 36 (1) ◽  
pp. 1-6
Author(s):  
FO Idagu ◽  
NM Ogarekpe ◽  
TI Ugama
Keyword(s):  
Shear Resistance ◽  
Resistance Factor ◽  
Shear Stresses ◽  
Simplified Approach ◽  
Flat Slabs ◽  
European Code ◽  
Relationship Of ◽  
The Relationship

The distribution of shear stresses at the slab–column connection of flat slabs become non–uniform in the presence of unbalanced moment. The shear resistance (β) factor is used to account for this distribution of shear stresses due to the transfer of unbalanced moment at the slab–column connections. The provisions of the American, Canadian, European and Model codes, regarding the transfer of unbalanced moment at slab–column connections of flat slabs are compared. The relationship of β-factor to the ratio of critical perimeter to the control perimeter of an internal column have been plotted as a simplified approach and additional approximate factors have been found for an internal corner column and various locations of cantilevered edge, corner and internal corner columns encountered in practice by engineers. These additional approximate factors have been proposed for inclusion in European code for situations where adjacent spans do not differ by more than 25%.http://dx.doi.org/10.4314/njt.v36i1.1

Inferences of deviatoric stress in actively deforming belts from simple physical models

1991 ◽  
Vol 337 (1645) ◽  
pp. 151-164 ◽  
Keyword(s):  
Unit Length ◽  
Physical Models ◽  
Shear Stresses ◽  
Upper Crust ◽  
Western North America ◽  
The Andes ◽  
Average Shear ◽  
Tectonic Style ◽  
Relationship Of ◽  
The Relationship

Observations of temperatures and heat flux near major thrust zones indicate that in their deep levels shear stresses may exceed 50-100 MPa. Within strike-slip zones shear stresses in the lower lithosphere may also approach 50-100 MPa, though shear stresses in the upper crust of those regions are probably much lower. The relationship of tectonic style to surface elevation in the Andes and Tibet yields an estimate of about 5 x 10 12 N m -1 for the force per unit length required to deform the lithosphere of these regions. This force per unit length is equivalent to an average shear stress of about 25 MPa through a lithosphere 100 km thick. The width-to-length ratios of active belts are consistent with deformation determined by the creep of the lower lithosphere rather than by friction on faults. The patterns of rotation of crustal blocks in western North America suggest that these blocks passively follow the deformation of a continuous substrate. The observations of deformation and the estimates of stress derived from them, both suggest that the upper continental crust is weak, relative to the lower parts of the lithosphere the deformation of which it follows passively. If this is so, determinations of stress in the upper crust may have only limited relevance to the deformation of the lithosphere as a whole.

Simplification of the Parametric Transformation Equations for Analysis of Plane Stress

2012 ◽  
Vol 591-593 ◽  
pp. 2499-2503
Author(s):  
Mao Lin Du ◽  
Guo Liang Chen ◽  
Kui Ying Pu
Keyword(s):  
Plane Stress ◽  
Maximum Stress ◽  
Extreme Value ◽  
Shear Stresses ◽  
Angular Parameter ◽  
Two Systems ◽  
Relationship Of ◽  
The Relationship ◽  
Parametric Transformation ◽  
Mohr’S Circle

For the analysis of plane stress, there are two methods, transformation of equation and Mohr’s circle. With the former method, the two principle angles are found by taking derivative to determine the extreme value of stresses. However, it is unknown which one of the two principle angles corresponding to the maximum stress. Moreover, the relationship between the two methods is inexplicit, as the angle of the rotation of the element is eliminated to derive the equation of Mohr’s circle. Using trigonometric relations, considering two systems of sign conventions for shear stresses, simplified parametric transformation equations are obtained. A unique principle angle is easy to be found corresponding to a principle stress. It is obvious that the graph of the simplified equations is a circle. The relationship of the angle of the rotation of the element and the angular parameter of the circle is explicit.

Punching Resistance of Flat Slabs with Openings – Experimental Investigation

2018 ◽  
Vol 272 ◽  
pp. 41-46 ◽  
Author(s):  
Tomáš Augustín ◽  
Ľudovít Fillo ◽  
Jaroslav Halvonik ◽  
Marián Marčiš
Keyword(s):  
Experimental Investigation ◽  
Experimental Work ◽  
Material Properties ◽  
Laboratory Tests ◽  
Shear Resistance ◽  
Punching Shear ◽  
Shear Stresses ◽  
Flat Slab ◽  
Flat Slabs ◽  
Contemporary Architecture

Flat slabs are commonly used structures in contemporary architecture. Although their common use there is still problem in design of these structures. The openings adjacent to a column are often used for plumbing and such a position of the openings increases shear stresses in the flat slab near the column. This paper deals with experimental work focused on the punching shear resistance of the flat slab specimens with openings adjacent to column compared to the flat slab specimens without openings. The opening influence is determined experimentally and by using models for the assessment of punching resistance from relevant standards and codes. The material properties of concrete and reinforcing steel were obtained from the laboratory tests.

The relationship of the scleractinian corals to the rugose corals

Paleobiology ◽  
1980 ◽  
Vol 6 (02) ◽  
pp. 146-160 ◽  
Author(s):  
William A. Oliver
Keyword(s):  
Critical Points ◽  
Scleractinian Corals ◽  
Convincing Evidence ◽  
Early Triassic ◽  
Rugose Corals ◽  
History Of ◽  
The Subject ◽  
Relationship Of ◽  
The Relationship ◽  
Biologic Factors

The Mesozoic-Cenozoic coral Order Scleractinia has been suggested to have originated or evolved (1) by direct descent from the Paleozoic Order Rugosa or (2) by the development of a skeleton in members of one of the anemone groups that probably have existed throughout Phanerozoic time. In spite of much work on the subject, advocates of the direct descent hypothesis have failed to find convincing evidence of this relationship. Critical points are:(1) Rugosan septal insertion is serial; Scleractinian insertion is cyclic; no intermediate stages have been demonstrated. Apparent intermediates are Scleractinia having bilateral cyclic insertion or teratological Rugosa.(2) There is convincing evidence that the skeletons of many Rugosa were calcitic and none are known to be or to have been aragonitic. In contrast, the skeletons of all living Scleractinia are aragonitic and there is evidence that fossil Scleractinia were aragonitic also. The mineralogic difference is almost certainly due to intrinsic biologic factors.(3) No early Triassic corals of either group are known. This fact is not compelling (by itself) but is important in connection with points 1 and 2, because, given direct descent, both changes took place during this only stage in the history of the two groups in which there are no known corals.

Skeletal elements of crinoid echinoderms: High-resolution structural and microanalytical results

1983 ◽  
Vol 41 ◽  
pp. 194-195
Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor
Keyword(s):  
High Resolution ◽  
Marine Invertebrates ◽  
Sea Urchins ◽  
Structural Features ◽  
Sea Stars ◽  
High Resolution Tem ◽  
Relationship Of ◽  
The Relationship ◽  
Insight Into

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.

Studies on Leukemogenic and Sarcomagenic Viruses

1970 ◽  
Vol 28 ◽  
pp. 156-157
Author(s):  
Leon Dmochowski
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Morphological Properties ◽  
Mode Of Development ◽  
Relationship Of ◽  
The Relationship

Electron microscopy has proved to be an invaluable discipline in studies on the relationship of viruses to the origin of leukemia, sarcoma, and other types of tumors in animals and man. The successful cell-free transmission of leukemia and sarcoma in mice, rats, hamsters, and cats, interpreted as due to a virus or viruses, was proved to be due to a virus on the basis of electron microscope studies. These studies demonstrated that all the types of neoplasia in animals of the species examined are produced by a virus of certain characteristic morphological properties similar, if not identical, in the mode of development in all types of neoplasia in animals, as shown in Fig. 1.

The relationship of IGE receptor topography to signaling activity in RBL-2H3 mast cells

1991 ◽  
Vol 49 ◽  
pp. 236-237
Author(s):  
J.R. Pfeiffer ◽  
J.C. Seagrave ◽  
C. Wofsy ◽  
J.M. Oliver
Keyword(s):  
Mast Cells ◽  
Protein A ◽  
Scattered Electron ◽  
Ige Receptor ◽  
Receptor Complexes ◽  
Ige Binding ◽  
Electron Imaging ◽  
Small Clusters ◽  
Relationship Of ◽  
The Relationship

In RBL-2H3 rat leukemic mast cells, crosslinking IgE-receptor complexes with anti-IgE antibody leads to degranulation. Receptor crosslinking also stimulates the redistribution of receptors on the cell surface, a process that can be observed by labeling the anti-IgE with 15 nm protein A-gold particles as described in Stump et al. (1989), followed by back-scattered electron imaging (BEI) in the scanning electron microscope. We report that anti-IgE binding stimulates the redistribution of IgE-receptor complexes at 37“C from a dispersed topography (singlets and doublets; S/D) to distributions dominated sequentially by short chains, small clusters and large aggregates of crosslinked receptors. These patterns can be observed (Figure 1), quantified (Figure 2) and analyzed statistically. Cells incubated with 1 μg/ml anti-IgE, a concentration that stimulates maximum net secretion, redistribute receptors as far as chains and small clusters during a 15 min incubation period. At 3 and 10 μg/ml anti-IgE, net secretion is reduced and the majority of receptors redistribute rapidly into clusters and large aggregates.

Severe Paradoxical Dysphonia in Two Young Women

1993 ◽  
Vol 2 (3) ◽  
pp. 52-55 ◽  
Author(s):  
Michael Collins ◽  
Robert McDonald ◽  
Robert Stanley ◽  
Timothy Donovan ◽  
C. Frank Bonebrake
Keyword(s):  
Young Women ◽  
Theoretical Basis ◽  
Therapeutic Regimen ◽  
Instrumental Data ◽  
Relationship Of ◽  
The Relationship

This report describes an unusual and persistent dysphonia in two young women who had taken a therapeutic regimen of isotretinoin for intractable acne. We report perceptual and instrumental data for their dysphonia, and pose a theoretical basis for the relationship of dysphonia to this drug. We also provide recommendations for reducing the risk of acquiring a dysphonia during the course of treatment with isotretinoin.

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