Main results of experimental studies of reinforced concrete structures of high-strength concrete B100 round and circular cross sections in torsion with bending

Abstract

Aim of the research to verify the proposed calculating apparatus and accumulate new experimental data on the complex resistance of reinforced concrete structures, experimental studies of such structures made of high-strength concrete of circular and circular cross-section were conducted at the testing base of the South-West State University. Method is experimental-theoretical. Results of experimental research the plots of the deflections and rotation angles, the dependency of deformations of concrete according to the testimony of the outlets of electrodesorption with respect to the calculated cross section 1-1. The main deformations of elongation and shortening of concrete were determined; the reinforcement was selected in such a way that in the stage preceding the destruction, it reached fluidity, so the stresses in the reinforcement are known. It is established that for reinforced concrete structures made of high-strength concrete of circular cross-section, as a rule, there is the development of two cracks, i.e. the round shape of the cross-section slightly reduces the concentration due to the structure of high-strength concrete. For the annular section there were several cracks, of which stands out the one on which the destruction occurs. On the steps preceding the destruction, this crack begins to prevail over the rest and has a maximum opening width. On the basis of experimental studies of reinforced concrete structures made of high-strength concrete of square and box sections, reliable data on the complex stress-strain state in the studied areas of resistance, such as: the values of the generalized load of cracking , and destruction ,, its level relative to the limit load; the distance between the cracks at different levels of cracking (up to the moment of destruction, as a rule, two or three levels are formed); crack widths at the level of the axis of the working armature, at a distance of two diameters from the axes of the armature and along the entire crack profile at various stages of loading, from which it follows that the crack opening at the level of the axis of reinforcement in 2-3 times less compared with the crack opening on the removal of 1.5-2 diameters of the working axis (longitudinal and transverse) reinforcement; the coordinates of the spatial formation of cracks; schematic drawings on tablets of education, development and opening of cracks of reinforced concrete constructions in torsion with bending. Thus, the experimental studies and the result provide an opportunity to test the developed computational model and its working hypotheses for assessing the resistance of reinforced concrete structures made of high-strength concrete in torsion with bending.

Strength Properties of Various Types of Fiber-Reinforced Concrete for Production of Driven Piles

“…(6) The impact resistance of fiber concrete reinforced with chip and wire rope steel fibers is lower than that of fiber concrete reinforced with DRAMIX 3D steel fibers. Increasing the length of wire rope steel fibers by 2-3 times has a negligible effect on the impact resistance of fiber-reinforced concrete before the appearance of initial defects, but this becomes more significant when approaching complete failure; (7) The presented correlation dependencies have sufficient reliability, indicating their potential use for an approximate prediction of the strength and energy parameters of fiber-reinforced concretes in comparative assessments.…”

“…Fibers in the composition of fiber-reinforced concrete are the steel elements (sections of wire, rope, cuts from steel sheet, elements in the form of steel needles, threads, etc.) [1,[3][4][5][6][7], glass fibers [2,4,8,9], basalt fibers [9][10][11][12][13], carbon fibers [9,13], polymer elements (polypropylene fibers, capron threads, cellulose threads) [9,13,14] and other used methods.…”

“…-Window and door lintels of residential and civil buildings [6]; -Floors of industrial buildings [14]; -Beams of rectangular cross-sections [7];…”

Results of experimental research of steel-concrete composite beam under cyclic freezing-thawing

“…However, there is still an open question on considering of alternating temperatures influence on behavior of steel-concrete composite beams. [14][15][16][17][18][19][20]. Hence experimental research of cyclic freezing-thawing (CFT) influence on behavior of steel-concrete composite elements with external steel shell was carried out.…”

The new hypothesis angular deformation and filling of diagrams in bending with torsion in reinforced concrete structures

“…Rectangular cross-sections are one of the most applicable, therefore the research of this type of cross-section is most important [10][11][12][13]. However, the complex stress state has not yet been sufficiently considered in scientific publications [14][15][16][17][18][19][20][21][22][23].…”