About Implementation Necessity into Designs of Extreme Strength Criterion Instead of the Deformation One

ABSTRACT

It is grounded the general strength design method on the cross (normal) sections which allows to solve any practical problems for the bending and eccentrically compressed-tensile RC elements up to the uniaxially compressed ones. Such method ought to use the complete set of Continuum Mechanics Equations (dynamic-static, geometric, constitutive for concrete and steel) and additional certain Strength Criterion (SC). In the current Codes all over the world the SC is applied as the known Deformation Strength Criterion (DSC). The DSC historic sources are analyzed and it is shown that its basic statement to find the concrete ultimate strain ε_cu for cross sections of RC elements from the descending branch of concrete compression diagram is wrong in consequence the series of causes and in particular because the ε_cu value is defined not only concrete properties but other cross section conditions too: reinforcement quantity and its tension diagram type, section shape, load character etc. Therefore it is grounded the new SC from consideration the development of stress-strain state in the uneven compressed concrete zone of RC element during loading with taking into account of concrete peculiarities as so called «pseudo(quasi)plastic» material. The new «Extreme Strength Criterion (ESC)» together with Continuum Mechanics Equations leads to the General Strength Design Method of Normal Sections (GSDMNS), which overcomes the above demerits of DSC and designs based on the one. The GSDMNS merits, design algorithms, software and proximity of theoretic and experimental values are discussed.

Keywords: RC element, normal section, strength criterion, concrete compression zone, ultimate strain,  pseudo(quasi)plasticity peculiarities, maximum load criterion, optimization design.

For citation: Mitrofanov V., Pinchuk N. About Implementation Necessity into Designs of Extreme Strength Criterion Instead of the Deformation One. Contemporary Issues of Concrete and Reinforced Concrete: Collected Research Papers. Minsk. Institute BelNIIS. Vol. 10. 2018. Pp. 58–77. https://doi.org/10.23746/2018-10-04




References:

1. Eurocode 2: Design of Concrete Structures – Part 1: General Rules for Buildings. – Brussels: CEN, 2002. 226 p.
2. fib: International Federation for Structural Concrete: Model Code 2010 for Concrete Structures. Berlin: Ernst&Sohn, 2013. 350 p.
3. Baykov V.N., Sigalov E.E. Zhelezobetonnye Konstruktsii: obshchiy kurs.5-e izd. [Reinforced concrete structures: Generalcourse. 5th ed.]. Moscow: Stroyizdat, 1991. 767 p. (rus)
4. Baklashov I.V. Deformirovanie i razrushenie porodnykh massivov [Deforming and failure of rock mass]. Moscow: Nedra, 1988. 271 p. (rus)
5. Goodman R.E. Introduction to Rock Mechanics. New York: John Wiley&Sons, 1980. 232 p.
6. Mansur M., Chin M., Wee T. Stress-Strain Relationship of High-Strength Fiber Concrete in Compression. Journal of Materials in Civil Engineering. 1999. v. 11. N. 2. Pp. 21–29.
7. Mansur M., Wee T., Chin M. Derivation of the complete stressstrain curves for concrete in compression. Magazine of Concrete Research. 1995. v. 47. N. 173. Pp. 285–290.
8. Tur V.V., Rak N.A. Prochnost i deformatsii betona v raschetakh konstruktsiy: monografiya [Strength and strains of concrete in structures designs: monograph]. Brest: Edition of BGTU, 2003. 252 p. (rus)
9. Mitrofanov V.P. Extreme strength criterion and design of RC elements. Structural Concrete. Journal of the fib. London:Thomas Telford, 2009. 10. N. 4. Pp. 163–172.
10. Mitrofanov V. The theory of Perfect Plasticity as the Elementary Mechanics of a Pseudo-Plastic Ultimate State of Concrete: Bases, Limitations, Practical Aspects, Improving. Proceedings of the 2nd fib Congress, June 5 – 8, 2006. Naples, Italy. Condensed Papers (1). Sessions 1 – 9. Pp. 496–497.
11. Cherepanov G.P. Mekhanika Khrupkogo razrusheniya [Fracture Mechanics]. Moscow: Nauka, 1974. 640 p. (rus)
12. Kachanov L.M. Osnovy teorii plastichnosti. Izd. 2-e [Essentials of plasticity theory]. Moscow: Nauka, 1969. 420 p.
13. Mitrofanov V.P. Investigation of cracks surface roughness and shear transfer strength of cracked HSC. Proceedings of the fib symposium 2008, Amsterdam, The Netherlands, 19–21 May 2008. London: Taylor&Francis Group. P. 134.
14. Mitrofanov V.P. Napryazhenno-deformirovannoe sostoyanie, prochnost i treshchinoobrazovanie zhelezobetonnykh elementov pri poperechnom izgibe. [Stress-strain state, strength and cracking of reinforced concrete elements under cross bending]. Ph. D. thesis. Moscow: VZISI, 1982. 42 p. (rus)
15. Rice J. The Mechanics of Earthquake Rupture. Proceedings of the International School of Physics "Enrico Fermi". Amsterdam: North – Holland. Publ. com. 1980. Pp. 555–649.
16. Metodicheskie recomendatsii po opredeleniyu prochnostnykh i structurnych kharakteristik betonov pri kratkovremennom i dlitelnom nagruzhenii. [Methodical recommendations by determination of strength and structural characteristics under short-time and long-time loading]. Moscow: NIIZHB, 1976. 56 p. (rus)
17. Gvozdev A.A. Struktura betona i nekotorye osobennosti ego mekhanicheskih svoystv. [Concrete structure and some peculiarities its mechanical properties]. In: Strength, structure alterations and strains of concrete: NIIZHB works. Moscow: Stroyizdat, 1978. Pp. 5–21. (rus)
18. Zaytsev Y.V. Modelirovanie deformatsiy i prochnosti betona metodami mekhaniki razrusheniya [Modelling of strains and strength of concrete by the Fracture Mechanics Methods]. Moscow: Stroyizdat, 1982. 196 p. (rus)
19. Minoux M. Programmation mathematique: theorie et algoritmes dunod. Paris: Bordas et G.N.E.T. – E.N.S.T., 1983. 488 p.
20. Mitrofanov V.P., Mitrofanov P.B. Algoritmy resheniya zadach prochnosti normalnykh secheniy zelezobetonnykh elementov na osnove ekstremalnykh kriteriev [Strength problems solving algorithms of RC elements normal sections on the basis of extreme criteria]. In: Scientific bulletin of building, Issue 69. Kharkov: CHNUBA, 2012. Pp. 137–148. (rus)
21. Mitrofanov P.B. Rozrakhunok mitsnosti stysnutykh zalizobetonnykh elementiv iz vykorustannyam vusokomitsnykh betoniv na osnovi deformatsiynoy modeli z ekstremalnym kriteriem [Strength design of compressed reinforced concrete elements with usage of high-strength concretes on the basis of deformation model with extreme criterion]. Ph.D. thesis. Poltava: PNTU, 2013. 24 p. (ukr)

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