Punching shear behavior of flat slabs composed of normal concrete and ECC under the unbalanced moment

Document Type : Research Article


Civil, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran


Load capacity and ductility are the two main characteristics of flat slab-column connections in highly seismic areas. To date, different methods have been employed to strengthen the connection against shear punching, including column capital, drop panel, high strength concrete, and shear reinforcement. In the current experimental study, the effect of using Engineered Cementitious Composite (ECC) on upgrading the punching shear strength of flat slabs under an unbalanced moment was investigated. ECC can provide the composite with features such as the ability to spread multiple cracks under load, strain hardening, shear force, scabbing strength, and high deformation. To this end, seven reinforced concrete flat slab specimens with the dimensions of 1000mm*1000mm*100 mm under the load with the eccentricity of 150mm were examined. The slabs were made from two layers of normal concrete and ECC in their thicknesses. The variable parameters included the unbalanced moment effect, improved interaction of the two materials, and ECC thickness. It was observed that improving the contact surface of normal concrete and ECC increased the shear capacity. In addition, the replacement of slab concrete with ECC increases the punching capacity and post-punching strength of the slab without a large and sudden drop in load. The change in failure mechanism was observed from a sudden and abrupt failure to a formable failure with high-energy absorption when using more ECC layer thicknesses.


Main Subjects

[1] Pan, Austin, and Jack P. Moehle. "Lateral displacement ductility of reinforced concrete flat plates." Structural Journal 86, no. 3 (1989): 250-258.
[2] Farhey, Daniel N., Moshe A. Adin, and David Z. Yankelevsky. "RC flat slab-column subassemblages under lateral loading." Journal of Structural Engineering 119, no. 6 (1993): 1903-1916.
[3] I. Robertson, G. Johnson, Cyclic lateral loading of nonductile slab-column connections, ACI Structural Journal, 103(3) (2006) 356.
[4] Tian, Ying, James O. Jirsa, Oguzhan Bayrak, and Jaime F. Argudo. "Behavior of slab-column connections of existing flat-plate structures." ACI Structural Journal 105, no. 5 (2008): 561.
[5] Megally, Sami, and Amin Ghali. "Punching shear design of earthquake-resistant slab-column connections." Structural Journal 97, no. 5 (2000): 720-730.
[6] Marzouk, H., Mohamed Emam, and M. Sameh Hilal. "Effect of high-strength concrete columns on the behavior of slab-column connections." ACI Structural Journal 93 (1996): 545-554.
[7] Park, Robert, and Shafiqul Islam. "Strength of slab-column connections with shear and unbalanced flexure." Journal of the Structural Division 102, no. 9 (1976): 1879-1901.
[8] Hawkins, Neil Middleton, Denis Mitchell, and Maw Shyong Sheu. Cyclic behavior of six reinforced concrete slab-column specimens transferring moment and shear. Division of Structures and Mechanics, Department of Civil Engineering, University of Washington, 1974.
[9] Park, Robert, and Shafiqul Islam. "Strength of slab-column connections with shear and unbalanced flexure." Journal of the Structural Division 102, no. 9 (1976): 1879-1901.
[10] Stark, Andrew, Baris Binici, and Oguzhan Bayrak. "Seismic upgrade of reinforced concrete slab-column connections using carbon fiber-reinforced polymers." ACI Structural Journal 102, no. 2 (2005): 324.
[11] Pan, Austin D., and JackK P. Moehle. "An experimental study of slab-column connections." Structural Journal 89, no. 6 (1992): 626-638.
[12] Cheng, Min-Yuan, Gustavo J. Parra-Montesinos, and Carol K. Shield. "Shear strength and drift capacity of fiber-reinforced concrete slab-column connections subjected to biaxial displacements." Journal of structural engineering 136, no. 9 (2010): 1078-1088.
[13] Zhang, Rui, Koji Matsumoto, Takayoshi Hirata, Yoshikazu Ishizeki, and Junichiro Niwa. "Shear behavior of polypropylene fiber reinforced ECC beams with varying shear reinforcement ratios." Journal of JSCE 2, no. 1 (2014): 39-53.
[14] Meng, Dan, C. K. Lee, and Y. X. Zhang. "Flexural and shear behaviours of plain and reinforced polyvinyl alcohol-engineered cementitious composite beams." Engineering Structures 151 (2017): 261-272.
[15] Ge, Wen-Jie, Ashraf F. Ashour, Xiang Ji, Chen Cai, and Da-Fu Cao. "Flexural behavior of ECC-concrete composite beams reinforced with steel bars." Construction and Building Materials 159 (2018): 175-188.
[16] Kim, Sun-Woo, and Hyun-Do Yun. "Crack-damage mitigation and flexural behavior of flexure-dominant reinforced concrete beams repaired with strain-hardening cement-based composite." Composites Part B: Engineering 42, no. 4 (2011): 645-656.
[17] Ge, Wenjie, Ashraf F. Ashour, Dafu Cao, Weigang Lu, Peiqi Gao, Jiamin Yu, Xiang Ji, and Chen Cai. "Experimental study on flexural behavior of ECC-concrete composite beams reinforced with FRP bars." Composite Structures 208 (2019): 454-465.
[18] Deng, Mingke, and Yangxi Zhang. "Seismic performance of high-ductile fiber-reinforced concrete short columns." Advances in Civil Engineering 2018 (2018).
[19] Wu, Chang, Zuanfeng Pan, Ray Kai Leung Su, Christopher KY Leung, and Shaoping Meng. "Seismic behavior of steel reinforced ECC columns under constant axial loading and reversed cyclic lateral loading." Materials and Structures 50, no. 1 (2017): 78.
[20] Cai, Jingming, Jinlong Pan, Hao Su, and Cong Lu. "Experimental study on the hysteretic behavior of ECC-encased CFST columns." Engineering Structures 173 (2018): 107-121.
[21] Hung, Chung-Chan, Wei-Ming Yen, and Kun-Hao Yu. "Vulnerability and improvement of reinforced ECC flexural members under displacement reversals: Experimental investigation and computational analysis." Construction and Building Materials 107 (2016): 287-298.
[22] Hosseini, Farshid, Bora Gencturk, Hadi Aryan, and Gustavo Cadaval. "Seismic behavior of 3-D ECC beam-column connections subjected to bidirectional bending and torsion." Engineering Structures 172 (2018): 751-763.
[23] Liang, Xingwen, and Tingting Lu. "Seismic evaluation of engineered cementitious composites beam–column–slab subassemblies with various column‐to‐beam flexural strength ratios." Structural Concrete 19, no. 3 (2018): 735-746.
[24] Choi, Hyun-Ki, Baek-Il Bae, and Chang-Sik Choi. "Lateral resistance of unreinforced masonry walls strengthened with engineered cementitious composite." International Journal of Civil Engineering 14, no. 6 (2016): 411-424.
[25] Deng, Mingke, and Shuo Yang. "Cyclic testing of unreinforced masonry walls retrofitted with engineered cementitious composites." Construction and Building Materials 177 (2018): 395-408.
[26] Li, Victor C. "Engineered cementitious composites (ECC) material, structural, and durability performance." 2008.
[27] Binici, Baris, and Oguzhan Bayrak. "Upgrading of slab–column connections using fiber reinforced polymers." Engineering structures 27, no. 1 (2005): 97-107.
[28] Halabi, Ziad, Faouzi Ghrib, Amr El-Ragaby, and Khaled Sennah. "Behavior of RC slab-column connections strengthened with external CFRP sheets and subjected to eccentric loading." Journal of Composites for Construction 17, no. 4 (2013): 488-496.
[29] Criswell, M. E. "Static and dynamic response of reinforced concrete slab-column connections." Special Publication 42 (1974): 721-746.