Betonarme kolonların dayanım zarflarının kesme dayanımı modelleri ile karşılaştırılması

Bu çalışmada sabit eksenel yük ve çevrimsel yatay yük etkisi altında test edilen oniki adet betonarme kolonun deneysel dayanımları ile yaygın olarak kabul gören yedi kesme dayanımı modelinden elde edilen kesme kapasiteleri değerlendirilmiştir. Bu değerlendirmede kolonların kesme açıklığı oranları, etriye çapları, beton dayanımları ve eksenel yük indeksleri birer parametre olarak dikkate alınmıştır. Değerlendirmeye alınan kesme dayanımı modellerinden üçü yönetmelik modelleridir. Diğer dört model ise artan düktilite talebine bağlı olarak çevrimsel yükleme ile kesme dayanımı azalmasını dikkate alan kesme dayanımı zarfı modelleridir. Değerlendirme neticesinde kesme dayanımı zarfları hem dayanımın belirlenmesinde hem de kesme dayanımı azalmasının benzeşiminde oldukça başarılı olmuştur. Yönetmelik modellerinin tasarıma yönelik olarak ihtiyatlı sonuçlar verdiği, ancak çevrimsel yükleme ile dayanım azalmasının dikkate alınması gerektiği görülmüştür. Kesme açıklığı oranı 1.5 olan kolonlar kesme hakim davranış için kritiktir ve yönetmeliklerde bu durum dikkate alınmalıdır. Eksenel yük indeksinin çevrimsel yük etkisi altında davranışa etkisi tüm modeller tarafından ayrıca ele alınmalıdır.

Anahtar Kelimeler:

Betonarme kolon, çevrimsel yük, kesme dayanımı, dayanım azalması modelleri

Comparison of strength envelopes of RC columns with shear strength models

The experimental strengths of twelve reinforced concrete columns, tested under the effect of constant axial load and cyclic lateral load, and the shear capacities obtained from seven widely accepted shear strength models were evaluated in this study. The shear spans, stirrup diameters, concrete strength, and axial load indexes of the columns were considered as parameters. Three of the shear strength models evaluated were regulation/code models. The other five models were shear strength envelope models that consider the shear strength degradation depending on cyclic loading and increasing ductility demand. The evaluation result showed that models of shear strength envelope are quite successful in both determining strength and simulating shear strength degradation. Regulation models take a conservative approach to design, but it has been observed that strength degradation with cyclic loading should be considered. Columns with a shear span of 1.5 are critical to shear-dominant behavior and regulations should take this into account. A further consideration is required for all models in assessing the effect of axial load index on behavior under cyclic loading.

Keywords:

RC columns, cyclic load, shear strength, strength degradation models,

PDF

___

FEMA 274.NEHRP commentary on the guidelines for the seismic rehabilitation of buildings. Federal Emergency Management Agency. Applied Technology Council. Washington D.C., 1997.
D.E. Biskinis. G.K. Roupakias and M.N. Fardis. Degradation of shear strength of reinforced concrete members with inelastic cyclic displacements. ACI Structural Journal. 101 (6). 773–783. 2004. https://doi.org/10.14359/13452
W. Ritter. Die bauweise hennebique Schweizerische Bauzeitung. 33. 59–61. 1899.
E. Mörsch. Concrete-steel construction (English translation by E. P. Goodrich of the original manuscript of the 1902). New York: McGraw-Hill; 1909.
F. De Luca and G.M. Verderame. A practice-oriented approach for the assessment of brittle failures in existing reinforced concrete elements Engineering Structures. 48. 373–388. 2013. https://doi.org/10.1016/ j.engstruct.2012.09.038
R. Park and T. Paulay. Reinforced Concrete Structures. John Wiley & Sons. Inc.; 1975.
F. J. Vecchio and M. P. Collins. The Modiﬁed Compression-Field Theory for Reinforced Concrete elements subjected to shear, ACI Journal. 83(2), 219–231. 1986. https://doi.org/10.14359/10416
E. C. Bentz. F. J. Vecchio and M. P. Collins. Simpliﬁed modiﬁed compression ﬁeld theory for calculating shear strength of reinforced concrete elements. ACI Structural Journal. 103 (4). 614–624. 2006. https://doi.org/10.14359/16438
CSA. Standard A23.3-04. Concrete Design Handbook. Cement Association of Canada. Canada: 2006.
AASHTO LRFD. Bridge design speciﬁcations. American Association of State Highway and Transportation Ofﬁcials. Washington DC. 2012.
M. J. N. Priestley, F. Seible, Y. Xiao and R. Verma. Steel jacket retroﬁtting of reinforced concrete bridge columns for enhanced shear strength Part 2: Test results and comparison with theory. ACI Material Journal. 91 (2), 537–551. 1994. https://doi.org/10.14359/4168
A. Lynn, Seismic evaluation of existing reinforced concrete building columns. University of California at Berkeley; 1999.
H. Sezen and J. P. Moehle, Seismic behavior of shear-critical reinforced concrete building columns. Seventh U.S. National Congress of Earthquake Engineering. Boston: Massachusetts: Earthquake Engineering Research Institute; 3847-385, 2002.
P. Colajanni. A. Recupero and N. Spinella, Shear strength degradation due to ﬂexural ductility demand in circular RC columns. Bulletin of Earthquake Engineering., 13. 1795–1807. 2015. https://doi.org/ 10.1007/s10518-014-9691-0
C. Del Vecchio. M. Del Zoppo. M. Di Ludovico. G.M. Verderame and A. Prota, Comparison of available shear strength models for non-conforming reinforced concrete columns. Engineering Structures. 148, 312-327. 2017. https://doi.org/10.1016/j.engstruct.2017. 06.045
M. J. N. Priestley. R. Verma and Y. Xiao, Seismic shear strength of reinforced concrete columns. Journal of Structural Engineering. vol. 120(8). 2310–2329. 1994. https://doi.org/10.1061/(asce)0733-9445(1994) 120:8(2310)
M. J. Kowalsky and M. J. N Priestley, Improved analytical model for shear strength of circular reinforced concrete columns in seismic regions. ACI Structural Journal, 97(3), 388–396. 2000. https://doi.org/10.14359/4633
ATC 32. Applied Technology Council. Improved Seismic Design Criteria for California Bridges. Provisional Recommendations. 1996.
H. Sezen and J.P. Moehle, Shear strength model for lightly reinforced concrete columns. Journal of Structural Engineering. 130(11), 1692–1703. 2004. https://doi.org/10.1061/(asce)07339445(2004)130:11(1692)
D. Biskinis and M. N. Fardis. Cyclic shear resistance for seismic design. based on monotonic shear models in fib Model Code 2010 and in the 2018 draft of Eurocode 2. Structural Concrete, 21, 1-22. 2019. https://doi.org/10.1002/suco.201900037
ACI 318-19. Building code requirements for structural concrete. American Concrete Institute. Farmington Hill. MI; 2019.
Eurocode-8. Design of structures for earthquake resistance. Part-1. General rules. seismic actions and rules for buildings. European Committee for Standardization. Brussels. 2004.
TBDY'18. Türkiye Bina Deprem Yönetmeliği-Deprem etkisi altında binaların tasarımı için esaslar. Afet ve Acil Durum Yönetimi Başkanlığı. Ankara. 2018.
TS500/2000. Betonarme yapıların tasarım ve yapım kuralları. Türk Standartları Enstitüsü. Ankara. 2000.
H. Banchman. Seismic Conceptual Design of Buildings – Basic principles for engineers, architects, building owners and authorities. Swiss Agency for Development and Cooperation, 3th edition, Bern; 2003.
M. Moretti, and T. P. Tassios, Behaviour of short columns subjected to cyclic shear displacements: experimental results. Engineering Structures, 29(8), 2018-29, 2007. https://doi.org/10.1016/j.engstruct. 2006.11.001
T. Dirikgil, and O. Atas, Experimental investigation of the performance of diagonal reinforcement and CFRP strengthened RC short columns. Composite Structures, 223, 1-15, 2019. https://doi.org/10.1016/j.compstruct. 2019.110984
T. Dirikgil, Experimental investigation of the contributions of CFRP and externally collar strengthening to the seismic performance of RC columns with different cross-sections. Structures, 24, 266-281, 2020. https://doi.org/10.1016/j.istruc. 2020.03.067
FEMA 461. Interim testing protocols for determining the seismic performance characteristics of structural and nonstructural components. Federal Emergency Management Agency. Washington. D. C., 2007.
FIB - Task Group 9.3. Bulletin 14: Externally bonded FRP reinforcement for RC structures. Lausanne. Switzerland: federation internationale du beton; 2001. https://doi.org/10.35789/fib.bull.0014.ch01
ACI 440. Guide for the design and construction of externally bonded FRP systems for strengthening existing structures. Farmington Hills, MI: 2008. https://doi.org/10.14359/51700867
CNR-DT 200. Guide for the design and construction of externally bonded FRP systems for strengthening existing structures. R1 ed. Rome: 2013.
H-G. Park. E-J. Yu and K-K. Choi, Shear-strength degradation model for RC columns subjected to cyclic loading. Engineering Structures, 34, 187-197, 2012. https://doi.org/10.1016/j.engstruct.2011.08.041