An approximate method of determination of shear stresses due to flexure in composite beams

1990 ◽  
Vol 28 (8) ◽  
pp. 735-750 ◽  
Author(s):  
J.M. Segura
Keyword(s):  
Approximate Method ◽  
Composite Beams ◽  
Shear Stresses ◽  
Method Of Determination

scholarly journals An analytical solution for static problems of curved composite beams

2019 ◽  
Vol 6 (1) ◽  
pp. 105-116 ◽  
Author(s):  
István Ecsedi ◽  
Ákos József Lengyel
Keyword(s):  
Analytical Solution ◽  
Cross Section ◽  
Radial Displacement ◽  
Fundamental Solutions ◽  
Composite Beams ◽  
Shear Stresses ◽  
Equilibrium Equations ◽  
Euler Beam ◽  
Internal Forces

AbstractAn analytical solution is presented for the determination of deformation of curved composite beams. Each cross-section is assumed to be symmetrical and the applied loads are acted in the plane of symmetry of curved beam. In-plane deformations are considered of composite curved beams. Assumed form of the displacement field assures the fulfillment of the classical Bernoulli-Euler beam theory. The curvature of beam is constant and the internal forces in a cross-section is replaced by an equivalent forcecouple system at the origin of the cylindrical coordinate system used. The internal forces are expressed in terms of two kinematical variables, which are the radial displacement and the rotation of the cross-sections. The determination of the analytical solutions of the considered static problems are based on the fundamental solutions. Linear combination of the fundamental solutions which are filling to the given loading and boundary conditions, gives the total solution. Closed form formulae are derived for the radial displacement, cross-sectional rotation, nomral and shear forces and bending moments. The circumferential and radial normal stresses and shear stresses are obtained by the integration of equilibrium equations. Examples illustrate the developed method.

THE INFLUENCE OF PLASTIC STRAINS ON THE DEPTH OF OPEN RESIDUAL CRACKS IN COMPRESSED ZONE PF CONCRETE

2020 ◽  
Vol 91 (5) ◽  
pp. 13-21
Author(s):  
S.O. KURNAVINA ◽  
◽  
I.V. TSATSULIN ◽  
Keyword(s):  
Approximate Method ◽  
Crack Formation ◽  
Seismic Loads ◽  
Plastic Strains ◽  
Method Of Determination ◽  
Internal Forces ◽  
Three Stages ◽  
Current Code ◽  
Finite Elements Model

A significant part of the territory of Russian Federation refers to seismically dangerous areas. In the current code in design of reinforced concrete buildings for seismic loads the development of plastic strains is supposed. They are taken into account while determining loads by introduction of reducing factor K1, but their influence on the strength of elements is neglected. Plastic strains of reinforcement lead to appearance of residual cracks in compressed zone of concrete and due to this the reduction of bearing capacity of bending elements takes place on following loading cycles. The approximate method of determination of the depth of open cracks and of the residual height of sections when changing the sign of internal forces after reaching the maximum deflection has been proposed. The depth of residual crack is determined from the condition of equilibrium of longitudinal forces with regard to stress-strain state of a section at three stages of loading: at a moment of achievement of maximum plastic strains, at the unloading stage and at a moment of the beginning of crack formation after changing the sign of internal forces. The comparison of results obtained by the approximate method and results of calculation of finite elements model of a beam has been carried out.

Development of a method for multielemental determination in water by EDXRF with radioisotopic source of 238Pu.

2019 ◽  
Vol 7 (2A) ◽  
Author(s):  
Camilo Fuentes Serrano ◽  
Juan Reinaldo Estevez Alvares ◽  
Alfredo Montero Alvarez ◽  
Ivan Pupo Gonzales ◽  
Zahily Herrero Fernandez ◽  
...  
Keyword(s):  
Thin Layer ◽  
Expanded Uncertainty ◽  
Considerable Decrease ◽  
X Ray ◽  
Precipitation Efficiency ◽  
Method Of Determination ◽  
Sensitivity Curves ◽  
Order Of Magnitude ◽  
Metrological Parameters

A method for determination of Cr, Fe, Co, Ni, Cu, Zn, Hg and Pb in waters by Energy Dispersive X Ray Fluorescence (EDXRF) was implemented, using a radioisotopic source of 238Pu. For previous concentration was employed a procedure including a coprecipitation step with ammonium pyrrolidinedithiocarbamate (APDC) as quelant agent, the separation of the phases by filtration, the measurement of filter by EDXRF and quantification by a thin layer absolute method. Sensitivity curves for K and L lines were obtained respectively. The sensitivity for most elements was greater by an order of magnitude in the case of measurement with a source of 238Pu instead of 109Cd, which means a considerable decrease in measurement times. The influence of the concentration in the precipitation efficiency was evaluated for each element. In all cases the recoveries are close to 100%, for this reason it can be affirmed that the method of determination of the studied elements is quantitative. Metrological parameters of the method such as trueness, precision, detection limit and uncertainty were calculated. A procedure to calculate the uncertainty of the method was elaborated; the most significant source of uncertainty for the thin layer EDXRF method is associated with the determination of instrumental sensitivities. The error associated with the determination, expressed as expanded uncertainty (in %), varied from 15.4% for low element concentrations (2.5-5 μg/L) to 5.4% for the higher concentration range (20-25 μg/L).

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