Shear-Lag Phenomenon in Cast-in-Site Reinforced Concrete Hollow Floor System

Shear-lag phenomenon exits in many long-web structure especially when the stiffness of web is much larger than that of the flange’s. In this paper, Energy-Variation Method is applied to interpret shear-lag phenomenon in cast-in-site reinforced concrete hollow floor system. Finite Element Method (FEM) and is then used to validate the analysis results. The solution for the variation equation for effective flange width is proposed by solving the differential equations using proper boundary conditions.

Buckling Analysis of Two-Span Continuous Beams with Lateral Elastic Brace under Uniform Load

Both total potential energy and buckling equation of two-span continuous beam with lateral elastic brace under uniform load are deduced, based on energy variation method and the principle of minimum potential energy. Buckling of H-beams is simulated by ANSYS software, then compared to theoretical value, validated its rationality. High precision buckling moment formula is regressed using 1stOpt which is a famous mathematical optimization analysis software in China. The relationship between lateral brace stiffness and buckling moment is obtained. Results: with lateral brace stiffness increases, critical bending moment of beam increases within up-limit, e.g. when lateral brace stiffness increases to certain extent, buckling moment no longer increases.

Zur geometrischen Struktur von CF5−, — eine wellenmechanische Untersuchung / The Geometrical Structure of CF0− , a Wave Mechanical Investigation

The geometrical structure of CF5− has been ab initio investigated, taking all 52 electrons into account, using the MOLPRO-Programm/SCF-MO-LC-(LCGO)-Method. After approximating the core by means of the energy variation method and varying the ηp-values and the C - F-distance a total energy of - 517,7008 a. u. with a C - F4,5-distance of 2.78 a. u. and a C - F1,2,3 -distance of 2.74 a. u. for the CF5−-system of the trigonal bipyramidal structure was found.Likewise a total energy of -517.7036 a. u. with a C - F -distance of 2.58 a. u. in the tetraedral CF4 and a CF4 - F−-distance of 5.80 a. u. for the CF4 -F−-system was found. The best C-F-distance of the tetraedral CF4 was given at a distance of 2.51 a. u.According to this investigation it can be concluded that the structure of the system CF4 - F− is the most stable one. An interesting result through the analysis of the electrondistribution is that the carbon atom is almost in all structure systems nearly unchanged.