DAİRESEL AGREGALI MODEL BOŞLUKLU BETONLARIN DİNAMİK DAVRANIŞININ SONLU ELEMAN YÖNTEMİ İLE ANALİZİ

Öz

Boşluklu beton, agrega tanelerinin birbirine ince bir çimento hamuru tabakası ile bağlanması sonucu oluşan, yüksek oranda mezo-boyutta boşluk içeren özel bir tip betondur. Güvenlik uygulamalarında kullanılmak üzere dayanımı arttırılmış boşluklu betonlar geliştirilmesi amacıyla gerçekleştirilen bir projede, boşluklu betonların dinamik davranışları sonlu eleman yöntemiyle analiz edilmiştir. Analizlerde, ABAQUS/Explicit programında tanımlı bulunan açık direct entegrasyon metodu kullanılarak dairesel agregalı boşluklu betonlar incelenmiştir. Boşluklu betonlar ve bir yalın betonda basınç gerilmesi kontürlerinin gelişiminden yola çıkarak dalga ilerlemesi hızı tahmin edilmiştir. Hesaplanan değerlerin literatürdeki değerlere ve deneysel ultrases dalga hızı sonuçlarına çok yakın olduğu belirlenmiştir. Bunun yanında iki farklı boyutta agrega içeren boşluklu betonun dayanımlarının birbirine neredeyse eşit olduğu tespit edilmiştir. Boşluklu betonlarda oluşan hasar dağılımı ve gerilme konsantrasyonları incelendiğinde, deneylerde de tespit edildiği gibi dinamik yükleme altında çoklu çatlaklar ve yaklaşık olarak agrega boyutunda fragmanlar oluştuğu görülmektedir. Bu nedenle, fragman boyutunun agrega boyutu tarafından belirlendiği tespit edilmiştir.

Anahtar Kelimeler

• Boşluklu beton,Açık sonlu eleman analizi,Dinamik analiz

Finite Element Analysis of the Dynamic Behavior of Model Porous Concretes with Circular Aggregates

Öz

Porous concrete is a special type of concrete that includes a high amount of meso-size air pores and is formed by the aggregate particles assembled by a thin layer of cement paste. In the scope of a research project, having an objective of designing enhanced strength porous concretes to be used in safety applications, dynamic properties of porous concretes were analyzed with finite element method. In the analyses, porous concretes with circular aggregates were analyzed by using the explicit direct integration technique implemented in ABAQUS/Explicit. Based on the analysis results, stress wave propagation speeds of porous concretes and a plain concrete were estimated based on stress contours. The numerically estimated values were found to be very close to the reference values in literature and the experimental results. On the other hand, the impact strengths obtained for two model porous concretes having different aggregate sizes were found to be nearly equal. When the computed damage distributions and stress concentrations were examined, it was seen that under dynamic loading, the fragments formed were approximately at the size of aggregates. Therefore, it is concluded that the fragment size in porous concretes is mainly determined by the size of the aggregates incorporated in the mixture.

Anahtar Kelimeler

• Porous concrete,Explicit finite element analysis,Dynamic analysis,Drop weight impact test

Kaynakça

1. Agar Ozbek, A.S.,Weerheijm, J.,Schlangen, E., Breugel, van K. (2013), Dynamic behavior of porous concretes under drop weight impact testing, Cement and Concrete Composites, 39: 1-11, doi:10.1016/j.cemconcomp.2013.03.012.
2. British Standards Institution (1997), Falsework performance requirements and general design, Draft prEN 12812, London, U.K.
3. Chen, Z., Shin, M., Adrawes, B. (2012), Numerical Simulation of Prestressed Concrete Crosstie and Fastening System, PCI Convention.
4. Chindaprasirt P., Hatanaka S., Chareerat T., Mishima N., Yuasa Y. (2008), Cement paste characteristics and porous concrete properties, Construction and Building Materials, 22(5): 894 901, doi:10.1016/j.conbuildmat.2006.12.007.
5. Chindaprasirt, P., Hatanaka, S., Mishima, N., Yuasa, Y., Chareerat, T. (2009), Effects of binder strength and aggregate size on the compressive strength and void ratio of porous concrete, International Journal of Minerals, Metallurgy , Materials, 16(6): 714-719, doi:10.1016/S1674-4799(10)60018-0.
6. Chopra, A.K. (2000), Dynamics of Structures: Theory and Applications to Earthquake Engineering, Prentice Hall.
7. Dann, J.H., Dann J.J. (2012), CK-12 Basic Physics, CK-12 Foundation.
8. Deo, O. , Neithalath, N. (2010), Compressive behavior of pervious concretes and a quantification of the influence of random pore structure features, Materials Science and Engineering: A, 528(1): 402-412, doi:10.1016/j.msea.2010.09.024.

9. Deutsches Institut für Normung (1982), Falsework calculation, design and construction DIN 4421:1982, Beuth Veriag GmbH, Berlin, Germany.
10. Elmer,W. VII, Taciroglu, E., McMichael, L. (2012), Dynamic Strength Increase of Plain Concrete From High Strain Rate Plasticity with Shear Dilation, International Journal of Impact Engineering, 45: 1–15, doi:10.1016/j.ijimpeng.2012.01.003.
11. Farooq, U., Gregory, K. (2010), Explicit Dynamic Simulation of Drop-Weight Low Velocity Impact on Carbon Fibrous Composite Panels, ARPN Journal of Engineering and Applied Sciences, 5(3): 50-61, doi:10.1.1.608.6986.
12. Ghafoori N, Dutta S. (1995), Building and nonpavement applications of no-fines concrete, Journal of Materials in Civil Engineering, 7(4): 286-9, doi:10.1061/(ASCE)0899-1561(1995)7:4(286).
13. Ghafoori N., Dutta S. (1995), Development of no-fines concrete pavement applications, Journal of Transport Engineering; 121: 283-8, doi:10.1061/(ASCE)0733-947X(1995)121:3(283).
14. Gorst, N.J.S., Williamson, S.J., Pallett, P.F. and Clark, L.A (2003), Friction in temporary works, Research Report, University of Birmingham, U.K.
15. Grondzik, W.T, Kwok, A.G., Stein, B., Reynolds, J.S. (2010), Mechanical and Electrical Equipment for Buildings, Wiley.
16. Hillerborg, A., Modeer M., Petersson P. E. (1976), Analysis of crack formation and crack growth in concrete by means of fracture mechanics and finite elements, Cement and Concrete Research, 6: 773–782, doi:10.1016/0008-8846(76)90007-7.
17. Huang, C.C., Wu, T.Y. (2009), A Study on Dynamic Impact of Vertical Concrete Cask Tip-over Using Explicit Finite Element Analysis Procedures, Annals of Nuclear Energy, 36(2): 213–221, doi:10.1016/j.anucene.2008.11.014.
18. Huebner, K.H., Dewhirst, D.L., Smith, D.H. and Byrom T.G. (2001), The Finite Element Method for Engineers, Wiley.
19. Jankowiak, T., Lodygowski T. (2005), Identification of Parameters of Concrete Damage Plasticity Constitutive Model, Foundations of Civil and Environmental Engineering, 6: 53-69.
20. Lee, J., Fenves G.L. (1998), A Plastic Damage Model for Cyclic Loading of Concrete Structures, ASCE Journal of Engineering Mechanics, 124: 892–900, doi:10.1061/(ASCE)0733-9399(1998)124:8(892).
21. Lubliner, J., Oliver, J., Oller, S., Oñate, E. (1989), A Plastic-Damage Model for Concrete, International Journal of Solids and Structures, 25(3): 229-326, doi:10.1016/0020-7683(89)90050-4.
22. Marolf A, Neithalath N, Sell E, Wegner K, Weiss J, Olek J. (2004), Influence of aggregate size and gradation on the acoustic absorption of enhanced porosity concrete, ACI Materials Journal, 101(1): 82-91, doi:10.14359/12991.
23. Noh, G., Bathe K.J. (2013), An Explicit Time Integration Scheme for the Analysis of Wave Propagations, Computers and Structures, 129: 178–193, doi:10.1016/j.compstruc.2013.06.007.
24. Nolan, D. P. (2010), Handbook of Fire and Explosion Protection Engineering Principles, Elsevier, UK.
25. Schön, J.H. (2015), Physical Properties of Rocks : Fundamentals and Principles of Petrophysics, Elsevier.
26. Siad, L., Ouali, M.O. , Benabbes, A. (2008), Comparison of Explicit and Implicit Finite Element Simulations of Void Growth and Coalescence in Porous Ductile Materials, Materials and Design, 29(2): 319–329, doi:10.1016/j.matdes.2007.02.003.
27. Simulia_1 (2013), ABAQUS Analysis User’s Manual 6.13.
28. Sun J.S., Lee, K.H., Lee, P.H. (2000), Comparison of Implicit and Explicit Finite Element Methods for Dynamic Problems, Journal of Materials Processing Technology, 105(1-2): 110-118, doi:10.1016/S0924-0136(00)00580-X.
29. Susila, E., Hryciw, R.D. (2003), Large Displacement FEM Modelling of the Cone Penetration Test (CPT) in Normally Consolidated Sand, International Journal for Numerical and Analytical Methods in Geomechanics, 27(7): 585–602, doi: 10.1002/nag.287.
30. Tarque, N.S. (2011), Numerical modelling of the seismic behavior of adobe buildings, PhD Thesis, University of Pavia, Italy.
31. Wu, S.R., Gu, L. (2012), Introduction to the Explicit Finite Element Method for Nonlinear Transient Dynamics, Wiley.
32. Yang J, Jiang G. (2003), Experimental study on properties of pervious concrete, Cement and Concrete Research, 33(3): 381-6, doi:10.1016/S0008-8846(02)00966-3.
33. Zhang, L. (2017), Engineering Properties of Rocks (Second Edition), Butterworth-Heinemann, ISBN: 978-0-12-802833-9
34. Zhao J. (2009) Rock Mechanics for Civil Engineers Lecture Notes, Swiss Federal Institute of Technology, Zürich, Switzerland.