بررسی اثر اتصال سرد بر روی رفتار لرزه‌ای قاب خمشی بتن مسلح

نوع مقاله : پژوهشی اصیل (کامل)

نویسندگان
احسان کریمی 1
وحید رضا کلات جاری 2
1 دانشجوی دکتری مهندسی سازه، دانشکده عمران، دانشگاه صنعتی شاهرود
2 دانشیار گروه سازه، دانشکده عمران، دانشگاه صنعتی شاهرود
چکیده
یکی از مسائل رایج در اجرای درجای ساختمان­های بتن­آرمه، ایجاد اتصال سرد در نقاط قطع بتن­ریزی می­باشد. طبق آیین­نامه ACI 224.3R-95 محل قرارگیری اتصال سرد بر روی ستون­ها می بایست در زیر تیر و بالای دال سقف باشد. اتصال سرد نوعی ضعف یا نقص در بتن محسوب شده و باعث عدم یکپارچگی بتن سازه می­شود. این عدم یکپارچگی می­تواند بر روی رفتار بتن و در نهایت بر روی رفتار سازه بتنی تاثیرگذار باشد. اصولاً طراحان، سازه­های بتنی را براساس آیین­نامه­های رایج بدون لحاظ کردن اتصال­های سرد و با فرض یکپارچه بودن بتن سازه طراحی می­کنند. این در حالی است که در اجرا، بروز اتصال سرد در برخی نواحی خاص از سازه امری اجنتاب­ناپذیر است. در این تحقیق ابتدا رفتار اتصال سرد مدل­سازی گردیده است. سپس یک قاب بتن­آرمه یک طبقه یک دهانه مدل­سازی شده است. پس از اطمینان از صحت مدل عددی اتصال سرد و قاب، یک قاب بتن مسلح حاوی اتصال سرد بر روی ستون­های آن در محل­های زیر تیر و بالای پی مدل­سازی شده است. سپس به منظور بررسی رفتار لرزه­ای، یک بارگذاری جانبی یکنوا به صورت پوش-آور یکبار به قاب با اتصال سرد و بار دیگر به قابی نظیر و یکپارچه بدون اتصال سرد، اعمال گردیده است. با مشاهده نتایج مشخص گردید که تحت بارگذاری یکنوا، وجود اتصال سرد تاثیر چندانی بر روی حداکثر نیروی جانبی قابل تحمل قاب نداشته، اما باعث کاهش حدود 30 درصدی شکل­پذیری قاب مورد نظر شده است.

کلیدواژه‌ها

موضوعات

عنوان مقاله English

Investigating The Effect of Cold-Joint on Seismic Behavior of Reinforced Concrete Moment Resisting Frame

نویسندگان English

ehsan karimi 1
Vahid reza Kalatjari 2
1 Ph.D. Candidate, Department of Civil Engineering, Shahrood University of Technology, Shahrood, Iran
2 Associate Professor, Department of Civil Engineering, Shahrood University of Technology, Shahrood, Iran
چکیده English

One of the common issues in the cast-in-situ reinforced concrete structures is creating a construction joint (cold joint) caused by an interruption or delay in the concreting operations. According to ACI 224.3R-95, construction joints in columns are to be provided below the beam for lower story columns and above the floor slab for upper story columns. The cold joint is a weakness or defect in the concrete, which results in the non-integrity of the concrete. For this reason, the performance of concrete elements with the cold-joint is under the influence of that behavior. The seismic design procedure for in-situ construction generally considers that the connection of beam and column that frames into the joint is monolithic in nature. But in actual construction, it is not possible to cast columns of the multi-story frame in one go and therefore, a cold joint is inevitable in all the upper story columns immediately above the lower story slab. In this research, firstly, cold joint behavior is modeled. The model of concrete damage plasticity used for the modeling the concrete behavior and the surface-based cohesive behavior with the traction-separation response used for the modeling the cold-joint. The three-point bending beam specimens with the same compressive strengths of concrete on both sides of the cold-joint have been used to verify the opening mode behavior of the cold joint from the experimental results. Three different sizes of the beam were considered to ensure the validation of opening mode behavior for the cold joint. So, the push-off test specimens have been used to verify the shear-friction behavior of the cold joint from the experimental results. Three same specimens with same compressive strengths of concrete on both sides of the cold-joint and the different number of steel connectors crossing the interface surface of the push-off specimens were considered to ensure the validation of shear-friction behavior for the cold joint. Then, a single-story single-bay reinforced concrete frame is modeled. After ensuring the validity of the numerical model of the cold joint and frame, a reinforced concrete frame containing a cold joint is modeled on its columns at the below of the beam and the top of the foundation. Subsequently, in order to investigate seismic behavior, an In-plane monotonic loading, stroke-controlled pushover tests were performed once on a frame containing a cold joint and once again on the same frame but without a cold joint. From the result, prior to the yield point, there was no difference between the load-displacement curve of the monolithic frame and frame with cold joints. In the range between the yield point and the failure point in the frame, a relatively small difference was observed between the load-displacement curve of the monolithic frame and frame with cold joints. A significant effect on the frame behavior was achieved in monolithic frame and frame with cold joints in their ultimate displacement so that the ultimate displacement in the cold-joint state was reduced by about 30% compared to the monolithic one. In fact, the finding results showed that under monotonic loading, the existence of a cold joint hadn’t any effect on the maximum lateral force of the frame, but reduced the ductility of it by about 30%.

کلیدواژه‌ها English

Cold-Joint
Construction Joint
Reinforced Concrete Frame
Fracture mechanics
pushover analysis
Seismic behavior
ductility
[1] J. C. Kishen and P. S. Rao. Fracture of cold jointed concrete interfaces. Engineering fracture mechanics, vol. 74, no. 1, pp. 122-131, 2007.
[2] Y. Lim, M. Kim, S. Shin and V. Li. Numerical simulation for quasi-brittle interface fracture in cementitious bi-material system. In Proceedings of the Fourth International Conference on Fracture Mechanics of Concrete Structures, pp. 73-80, 2001.
[3] A. Standard. 224.3 R-95. Joints in Concrete Construction, 2013.
[4] R. Park and T. Paulay. Behaviour of reinforced concrete external beam-column joints under cyclic loading. In Proceedings of the 5th World Conference on Earthquake Engineering, Rome, 1973.
[5] B. Roy and A. I. Laskar. Cyclic behavior of in-situ exterior beam-column subassemblies with cold joint in column. Engineering Structures, vol. 132, pp. 822-833, 2017.
[6] S. Hakuto, R. Park and H. Tanaka. Seismic load tests on interior and exterior beam-column joints with substandard reinforcing details. Structural Journal, vol. 97, no. 1, pp. 11-25, 2000.
[7] H. Shiohara. New model for shear failure of RC interior beam-column connections. Journal of Structural Engineering, vol. 127, no. 2, pp. 152-160, 2001.
[8] M. Shin and J. LaFave. Reinforced concrete edge beam—column—slab connections subjected to earthquake loading. Magazine of Concrete Research, vol. 56, no. 5, pp. 273-291, 2004.
[9] V. G. Haach, A. L. H. D. C. El and M. K. El Debs. Evaluation of the influence of the column axial load on the behavior of monotonically loaded R/C exterior beam–column joints through numerical simulations. Engineering Structures, vol. 30, no. 4, pp. 965-975, 2008.
[10] T. Supaviriyakit and A. Pimanmas. Comparative performance of sub-standard interior reinforced concrete beam–column connection with various joint reinforcing details. Materials and Structures, vol. 41, no. 3, pp. 543-557, 2008.
[11] H. Zhou. Reconsideration of seismic performance and design of beam-column joints of earthquake-resistant reinforced concrete frames. Journal of structural engineering, vol. 135, no. 7, pp. 762-773, 2009.
[12] H.-J. Hwang, H.-G. Park, W.-S. Choi, L. Chung and J.-K. Kim. Cyclic loading test for beam-column connections with 600 MPa (87 ksi) beam flexural reinforcing bars. ACI Structural Journal, vol. 111, no. 4, pp. 913, 2014.
[13] B. Li and C. L. Leong. Experimental and numerical investigations of the seismic behavior of high-strength concrete beam-column joints with column axial load. Journal of Structural Engineering, vol. 141, no. 9, pp. 04014220, 2014.
[14] S. Barbhuiya and A. M. Choudhury. A study on the size effect of RC beam–column connections under cyclic loading. Engineering Structures, vol. 95, pp. 1-7, 2015.
[15] A. Masi, G. Santarsiero, G. P. Lignola and G. M. Verderame. Study of the seismic behavior of external RC beam–column joints through experimental tests and numerical simulations. Engineering Structures, vol. 52, pp. 207-219, 2013.
[16] M. T. De Risi, P. Ricci, G. M. Verderame and G. Manfredi. Experimental assessment of unreinforced exterior beam–column joints with deformed bars. Engineering Structures, vol. 112, pp. 215-232, 2016.
[17] N. Ning, W. Qu and Z. J. Ma. Design recommendations for achieving “strong column-weak beam” in RC frames. Engineering Structures, vol. 126, pp. 343-352, 2016.
[18] A. Pimanmas and P. Chaimahawan. Shear strength of beam–column joint with enlarged joint area. Engineering structures, vol. 32, no. 9, pp. 2529-2545, 2010.
[19] E. L. Grimsmo, A. H. Clausen, A. Aalberg and M. Langseth. A numerical study of beam-to-column joints subjected to impact. Engineering Structures, vol. 120, pp. 103-115, 2016.
[20] W. Kassem. Strut-and-tie modelling for the analysis and design of RC beam-column joints. Materials and Structures, vol. 49, no. 8, pp. 3459-3476, 2016.
[21] G. Somma, A. Pieretto, T. Rossetto and D. N. Grant. RC beam to column connection failure assessment and limit state design. Materials and Structures, vol. 48, no. 4, pp. 1215-1231, 2015.
[22] C. G. Karayannis, C. E. Chalioris and G. M. Sirkelis. Local retrofit of exterior RC beam–column joints using thin RC jackets—An experimental study. Earthquake Engineering & Structural Dynamics, vol. 37, no. 5, pp. 727-746, 2008.
[23] C. P. Antonopoulos and T. C. Triantafillou. Experimental investigation of FRP-strengthened RC beam-column joints. Journal of composites for construction, vol. 7, no. 1, pp. 39-49, 2003.
[24] S.-J. Hwang and H.-J. Lee. Analytical Model for Predicting Shear Strengths of Exterior Reinforced Concrete Beam-Column Joints for Sesimic Resistance. ACI Structural Journal, vol. 96, pp. 846-857, 1999.
[25] A. G. Tsonos. Cyclic load behavior of RC beam-column subassemblages of modern structures. Journal of Structural Engineering, vol. 104, no. 468, pp. 78, 2007.
[26] S. Sasmal, K. Ramanjaneyulu, B. Novák and N. Lakshmanan. Analytical and experimental investigations on seismic performance of exterior beam–column subassemblages of existing RC‐framed building. Earthquake Engineering & Structural Dynamics, vol. 42, no. 12, pp. 1785-1805, 2013.
[27] M. J. Favvata, B. A. Izzuddin and C. G. Karayannis. Modelling exterior beam–column joints for seismic analysis of RC frame structures. Earthquake Engineering & Structural Dynamics, vol. 37, no. 13, pp. 1527-1548, 2008.
[28] M. J. Favvata and C. G. Karayannis. Influence of pinching effect of exterior joints on the seismic behavior of RC frames. Earthquakes and Structures, vol. 6, no. 1, pp. 89-110, 2014.
[29] H. Shariatmadar and E. Zamani Beydokhty. An investigation of seismic response of precast concrete beam to column connections: experimental study. Asian Journal of Civil Engineering-Building And Housing, vol. 15, 2014.
[30] R. Park. A perspective on the seismic design of precast concrete structures in New Zealand. PCI journal, vol. 40, no. 3, 1995.
[31] C. W. French, O. Amu and C. Tarzikhan. Connections between Precast Elements—Failure Outside Connection Region. Journal of Structural Engineering, vol. 115, no. 2, pp. 316-340, 1989.
[32] G. S. Cheok and H. Lew. Model precast concrete beam-to-column connections subject to cyclic loading. PCI journal, vol. 38, no. 4, pp. 80-92, 1993.
[33] J. I. Restrepo-Posada. Seismic behaviour of connections between precast concrete elements, 1992.
[34] W. Xue and X. Yang. Seismic tests of precast concrete, moment-resisting frames and connections. PCI journal, vol. 55, no. 3, 2010.
[35] U. Ersoy and T. Tankut. Precast concrete members with welded plate connections under reversed cyclic loading. PCI Journal, vol. 38, no. 4, pp. 94-100, 1993.
[36] S. Ozden and O. Ertas. Behavior of unbonded, post-tensioned, precast concrete connections with different percentages of mild steel reinforcement. PCI journal, vol. 52, no. 2, 2007.
[37] R. Vidjeapriya and K. Jaya. Experimental study on two simple mechanical precast beam-column connections under reverse cyclic loading. Journal of Performance of Constructed Facilities, vol. 27, no. 4, pp. 402-414, 2012.
[38] H. Parastesh, I. Hajirasouliha and R. Ramezani. A new ductile moment-resisting connection for precast concrete frames in seismic regions: an experimental investigation. Engineering Structures, vol. 70, pp. 144-157, 2014.
[39] B. Roy and A. I. Laskar. Beam–column subassemblies with construction joint in columns above and below the beam. Magazine of Concrete Research, vol. 70, no. 2, pp. 71-83, 2017.
[40] T. Jankowiak and T. Lodygowski. Identification of parameters of concrete damage plasticity constitutive model. Foundations of civil and environmental engineering, vol. 6, no. 1, pp. 53-69, 2005.
[41] P. Kmiecik and M. Kamiński. Modelling of reinforced concrete structures and composite structures with concrete strength degradation taken into consideration. Archives of civil and mechanical engineering, vol. 11, no. 3, pp. 623-636, 2011.
[42] B. Alfarah, F. López-Almansa and S. Oller. New methodology for calculating damage variables evolution in Plastic Damage Model for RC structures. Engineering Structures, vol. 132, pp. 70-86, 2017.
[43] P. Desayi and S. Krishnan. Equation for the stress-strain curve of concrete. In Journal Proceedings, pp. 345-350, 1964.
[44] S. Majewski. The mechanics of structural concrete in terms of elasto-plasticity. Publishing House of Silesian University of Technology, Gliwice, 2003.
[45] B. Massicotte, A. E. Elwi and J. G. MacGregor. Tension-stiffening model for planar reinforced concrete members. Journal of Structural Engineering, vol. 116, no. 11, pp. 3039-3058, 1990.
[46] P. Beverly. fib model code for concrete structures 2010: Ernst & Sohn, 2013.
[47] J. Lubliner, J. Oliver, S. Oller and E. Onate. A plastic-damage model for concrete. International Journal of solids and structures, vol. 25, no. 3, pp. 299-326, 1989.
[48] Y. Tao and J.-F. Chen. Concrete damage plasticity model for modeling FRP-to-concrete bond behavior. Journal of composites for construction, vol. 19, no. 1, pp. 04014026, 2014.
[49] G. Al-Chaar, M. Issa and S. Sweeney. Behavior of masonry-infilled nonductile reinforced concrete frames. Journal of Structural Engineering, vol. 128, no. 8, pp. 1055-1063, 2002.
[50] S. G. Shah and J. C. Kishen. Nonlinear fracture properties of concrete–concrete interfaces. Mechanics of Materials, vol. 42, no. 10, pp. 916-931, 2010.
[51] Hibbett, Karlsson and Sorensen. ABAQUS/standard: User's Manual: Hibbitt, Karlsson & Sorensen, 1998.
[52] J. M. Gere, and Timoshenko, S. P. Mechanics of Materials. Boston, Massachusetts: PWS Publishing Company, 1997.
[53] Y. Lim, M. Kim, S. Shin and V. C. Li. Numerical simulation for quasi-brittle interface fracture in cementitious bi-material system, 2001.
[54] M. N. Fardis and E.-S. Chen. A cyclic multiaxial model for concrete. Computational mechanics, vol. 1, no. 4, pp. 301-315, 1986.
[55] R. L. Park, R. Park and T. Paulay. Reinforced concrete structures: John Wiley & Sons, 1975.
[56] D. Figueira, C. Sousa, R. Calçada and A. S. Neves. Push-Off Tests in the Study of Cyclic Behavior of Interfaces between Concretes Cast at Different Times. Journal of Structural Engineering, vol. 142, no. 1, pp. 04015101, 2015.
[57] P. W. Birkeland and H. W. Birkeland. Connections in precast concrete construction. In Journal Proceedings, pp. 345-368, 1966.
[58] H. Dulacska. Dowel action of reinforcement crossing cracks in concrete. In Journal Proceedings, pp. 754-757, 1972.
[59] E. Vintzēleou and T. Tassios. Mathematical models for dowel action under monotonic and cyclic conditions. Magazine of concrete research, vol. 38, no. 134, pp. 13-22, 1986.
[60] P. Soroushian, K. Obaseki and M. C. Rojas. Bearing strength and stiffness of concrete under reinforcing bars. Materials Journal, vol. 84, no. 3, pp. 179-184, 1987.
[61] E. Júlio, D. Dias-da-Costa, F. Branco and J. Alfaiate. Accuracy of design code expressions for estimating longitudinal shear strength of strengthening concrete overlays. Engineering Structures, vol. 32, no. 8, pp. 2387-2393, 2010.
[62] R. Park. Evaluation of ductility of structures and structural assemblages from laboratory testing. Bulletin of the New Zealand national society for earthquake engineering, vol. 22, no. 3, pp. 155-166, 1989.
[63] S. A. Sheikh and S. S. Khoury. Confined concrete columns with stubs. ACI Structural Journal, vol. 90, pp. 414-414, 1993.
[64] T. Paulay and M. N. Priestley. Seismic design of reinforced concrete and masonry buildings, 1992.
[65] ASCE. Seismic rehabilitation of existing buildings, 2007.
[66] B. S. S. Council. Prestandard and commentary for the seismic rehabilitation of buildings. Report FEMA-356, Washington, DC, 2000.
[67] S.-K. Hwang and H.-D. Yun. Effects of transverse reinforcement on flexural behaviour of high-strength concrete columns. Engineering structures, vol. 26, no. 1, pp. 1-12, 2004.
[68] M. Priestley and R. Park. Strength and ductility of concrete bridge columns under seismic loading. Structural Journal, vol. 84, no. 1, pp. 61-76, 1987.
مهندسی عمران مدرس
دوره 19، شماره 4
مهر و آبان 1398
صفحه 145-159