مدل‌سازی و ارزیابی روش‌های طراحی تیرهای عمیق بتن مسلح

نوع مقاله: مقاله پژوهشی

نویسندگان

1 استادیار گروه مهندسی عمران، دانشگاه آزاد، واحد قم، قم، ایران

2 مهندسی عمران، دانشکده عمران و معماری، موسسه ی پویش، قم، ایران.

چکیده

تیرهای عمیق به تیرهایی گفته می‌شود که در مقایسه با تیرهای معمولی،‌ دارای نسبت زیاد ارتفاع به دهانه باشند. در تیرهای عمیق به دلیل داشتن هندسه‌ی خاص توزیع کرنش در مقطع به صورت خطی نیست و عموماً دارای رفتاری برشی هستند. بر همین اساس این تیرها به روش متفاوتی نسبت به تیرهای معمولی طراحی می‌شوند. طراحی تیرهای عمیق با توجه به کاربرد وسیع آن‌ها یک مسئله حیاتی در مهندسی سازه به‌حساب می‌آید. تا‌کنون مطالعات متعددی برای تعیین روابط یا روش‌هایی برای طراحی تیرهای عمیق صورت گرفته است. این مطالعات منجر به پیدایش روش‌های مختلف برای تحلیل و طراحی این تیرها شدند. با این حال آیین نامه بتن ایران بدون توجه به این روش ها مدت هاست از یک رابطه ساده و قدیمی استفاده می کند. در این پژوهش روش‌ها و روابط معتبر ارائه‌شده توسط دیگر محققان در کنار روش آیین نامه بتن ایران بررسی و ارزیابی شدند. مقایسه روش آیین نامه بتن ایران و بست‌وبند آیین‌نامه‌ی بتن آمریکا در طراحی تیرهای عمیق بتن مسلح نشان داد که نتایج روش بست‌وبند همبستگی بیشتری با نتایج آزمایشگاهی دارند. طراحی مطابق با روش بست‌وبند منجر به 27 درصد خطای کمتر یا به عبارتی دیگر 27 درصد صرفه‌جویی در مصرف مصالح نسبت به روش آیین‌نامه بتن ایران می شود. همچنین، در این پژوهش رابطه‌ی جدیدی برای پیش‌بینی نیروی برشی تیرهای عمیق بتن مسلح بر اساس 240 نمونه‌ی آزمایشگاهی با استفاده از روش رابطه‌سازی ژنتیک ارائه شد. رابطه ی پیشنهادی توانست با میانگین خطای 6% نتایج آزمایشگاهی را پیش بینی کند.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Modeling and Evaluation of Design Methods of Reinforced Concrete Deep Beams

نویسندگان [English]

  • Mahdi Moradi 1
  • Sayed Mohammad Bagher Saraf Zadeh 2
1 Assistant Professor, Department of Civil Engineering, Qom Branch, Islamic Azad University, Qom, Iran.
2 Department of Civil Engineering, School of Civil Engineering and Architecture, Pooyesh Institute, Qom, Iran
چکیده [English]

Abstract
Deep beam is a Deep beam is a beam having large depth/thickness ratio compired to conventional beams. In deep beams, the bending strain distribution through the depth of transverse sections of beam considerably deviates from the linear distribution, predicted by elementary bending theory of beams. So their behavior is different with ordinary beams and are designed based on shear strength. The design of deep beams, due to their widespread use, is a crucial issue in structural engineering. So far, numerous studies have been done to determine the shear strength relations or models for deep beams. These studies led to various methods for analysis and design of these beams. Some of these approaches have shown adequate accuracy when applied to small sets of beam tests, while their ability to predict the effect of a large range of test variables remains unknown.  One widely used approach to determine shear strength of is the strut-and-tie method, which is employed by the American Concrete Association (ACI). However, It's been a long time since the iranian concrete code, regardless of this research, uses a direct relation to the design of deep beams. In this research, reliable methods and relations provided by other researchers along with the iranian concrete code method for deep beam design have been evaluated based on 240 experimental specimens. Moreover, a new equation for predicting the shear strength of RC deep beams using the genetic programming (GP) method is presented. Some input and output data should be used for feeding GP and equations producing. For this purpose, the results of 240 experimental specimens collected from 9 different references were used. This equation was only based on primary specifications RC deep beams. This equation was compared with other methods presented in the related literature. In addition, based on this equation, the effect of different parameters on shear strength of RC deep beams were investigated. The results of this study showed that the proposed equation had acceptable accuracy compared to the experimental results and other equation presented in the literature. The proposed equation could predict the experimental results with an average error of 6%. Comparison of the results of the of iranian concrete code method in the design of deep beams with ACI method results showed that design in accordance with the ACI method resulted in a 27% lower error.
 


کلیدواژه‌ها [English]

  • reinforced concrete
  • Deep beam
  • Genetic programming
  • Shear strength
[1]     Moradi M, E‌s‌f‌a‌h‌a‌n‌i M. (2016). O‌ptimization of strut and tie models on deep beams with opening. Sharif Journal of Civil Engineering. 32:67-77 (In Persian).

[2]     ACI Committee, Standardization IOf, editors. (2014). Building code requirements for structural concrete (ACI 318-14) and commentary: American Concrete Institute.

[3]     S. Ershadi, (1996). Investigation of the behavior and failure of simply supported concrete beams With a span ratio of 2 to 3, Iran University of Science & Technology, Tehran, Iran, 1996 (In Persian).

[4]     Fernández Ruiz M, Muttoni A. (2007). On development of suitable stress fields for structural concrete. ACI, Structural Journal. 104:495-502.

[5]     Kong FK. (2006). Reinforced concrete deep beams: CRC Press.

[6]     Liu J, Mihaylov BI. (2016). A comparative study of models for shear strength of reinforced concrete deep beams. Engineering Structures. 112:81-9.

[7]     AAashto. (2012). Bridge design specifications, in, American Association of State Highway and Transportation Officials.

[8]     Shahin, MA. (2016). State-of-the-art review of some artificial intelligence applications in pile foundations. Geoscience Frontiers, 7(1), 33-44.

[9]     Moradi M, Bagherieh A, Esfahani MR. (2016). Relationship of tensile strength of steel fiber reinforced concrete based on genetic programming. Iran University of Science & Technology. 6(3):349-63.

[10] Moradi M, Bagherieh AR, Esfahani MR. (2019). Tensile modeling of steel fiber reinforced concrete. Asian Journal of Civil Engineering. 20(2):269-80.

[11] Ashour A, Alvarez L, Toropov V. (2003). Empirical modelling of shear strength of RC deep beams by genetic programming. Computers & structures. 81(5):331-8.

[12] Gandomi AH, Alavi AH, Shadmehri DM, Sahab M. (2013). An empirical model for shear capacity of RC deep beams using genetic-simulated annealing. Archives of Civil and Mechanical Engineering.13(3):354-69.

[13] Cheng M-Y, Cao M-T. (2014). Evolutionary multivariate adaptive regression splines for estimating shear strength in reinforced-concrete deep beams. Engineering Applications of Artificial Intelligence. 28:86-96.

[14] Chou J-S, Ngo N-T, Pham A-D. (2015). Shear strength prediction in reinforced concrete deep beams using nature-inspired metaheuristic support vector regression. Journal of Computing in Civil Engineering. 30(1):04015002.

[15] Lee S-C. (2003. Prediction of concrete strength using artificial neural networks. Engineering Structures. 25(7):849-57.

[16] Arabzade, A., Noori Soola, A. (2015). Investigating Effective Parameters in Shear Strength of Deep Beams without Shear Reinforcement. Concrete Research, 7(2), 17-30.

[17] Iranian Concrete Code. (2013). Design and analysis rules of concrete structures. Management and Planning Organization of Iran, Tehran, Iran.

[18] Tjhin TN, Kuchma DA. (2002). Computer-based tools for design by strut-and-tie method: Advances and challenges. Structural Journal. 99(5):586-94.

[19] Koza JR. (1992). Genetic programming: on the programming of computers by means of natural selection: MIT press.

[20] Silva S, Almeida J. (2003). Gplab-a genetic programming toolbox for matlab. Proceedings of the Nordic MATLAB conference; Citeseer.

[21] Clark AP. (1951). Diagonal tension in reinforced concrete beams. Journal Proceedings.

[22] Ramakrishnan V, Ananthanarayana Y. (2016). Ultimate strength of deep beams in shear. Journal Proceedings.

[23] Kong F-K, Robins PJ, Cole DF. (1970). Web reinforcement effects on deep beams. Journal Proceedings.

[24] Manuel RF, Slight BW, Suter GT. (1971). Deep beam behavior affected by length and shear span variations. Am Concrete Inst Journal & Proceedings. 68(12).

[25] Smith K, Vantsiotis A, editors. (1982). Shear strength of deep beams. Journal Proceedings.

[26] Tan K-H, Kong F-K, Teng S, Guan L. (1995). High-strength concrete deep beams with effective span and shear span variations. Structural Journal. 92(4):395-405.

[27] Oh J-K, Shin S-W. (2001). Shear strength of reinforced high-strength concrete deep beams. Structural Journal. 98(2):164-73.

[28] Aguilar G, Matamoros AB, Parra-Montesinos G, Ramírez JA, Wight JK. (2002). Experimental Evaluation of Design Procedures for Shear Strength of Deep Reinfoced Concrete Beams: American Concrete Institute.

[29] Quintero-Febres CG, Parra-Montesinos G, Wight JK. (2006). Strength of struts in deep concrete members designed using strut-and-tie method. ACI Structural Journal;103(4):577.

[30] Rogowsky DM, MacGregor JG, Ong SY. (1986). Tests of reinforced concrete deep beams. Journal Proceedings.

[31] Subedi N, Vardy AE, Kubotat N. (1986). Reinforced concrete deep beams some test results. Magazine of concrete Research. 38(137):206-19.

[32] Tan K-H, Kong F-K, Teng S, Weng L-W. (1997). Effect of web reinforcement on high-strength concrete deep beams. Structural Journal. 94(5):572-82.

[33] Tan K-H, Teng S, Kong F-K, Lu H-Y. (1997). Main tension steel in high strength concrete deep and short beams. Structural Journal. 94(6):752-68.

[34] Hong S-G, Kim D-J, Kim S-Y, Hong NK. (2002). Shear strength of reinforced concrete deep beams with end anchorage failure. Structural Journal. 99(1):12-22.

[35] Arabzadeh, A., Aghayari, R., & Rahai, A. R. (2011). Investigation of experimental and analytical shear strength.