Serviceability of Post-fire RC Rafters with Openings of Different Sizes and Shapes


  • Bashar Abdulkareem College of Engineering - University of Baghdad
  • Amer F. Izzet College of Engineering - University of Baghdad



This study deals with the serviceability of reinforced concrete solid and perforated rafters with openings of different shapes and sizes based on an experimental study that includes 12 post-fire non-prismatic reinforced concrete beams (solid and perforated). Three groups were formed based on heating temperature (room temperature, 400 °C, and 700 °C), each group consisting of four rafters (solid, rafters with 6 and 8 trapezoidal openings, and rafter with eight circular openings) under static loading. A developed unified calculation technique for deflection and crack widths under static loading at the service stage has been provided, which comprises non-prismatic beams with or without opening exposed to flexure concentrated force. Two approaches were used to compute the deflection: The first attempt was conducted by using the moment of inertia for solid non-prismatic beam and reduced for those with openings by the ratio of residual rafter self-weight. The second was performed by using the moment of inertia of transformed cracked sections depending on the segmental rafter method. The crack width was determined using the ACI code's equation. The analytical and experimental results were evaluated and found to be in good agreement.


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• ACI Standard: Commentary on Building Code Requirements for Structural Concrete (ACI 318R-95), 1995.

• ASTM, E., 2016. ASTM E119-16a. Standard Test Methods for Fire Tests of Building Construction and Materials,” ASTM International, West Conshohocken, PA: 21.

• Chang, Yun-Fei, Yih-Houng Chen, Maw-Shyong Sheu, and George C Yao. 2006. Residual stress-strain relationship for concrete after exposure to high temperatures, Cement and Concrete Research, 36: 1999-2005.

• Darwin, D., Dolan, C. W., and Nilson, A. H., 2016. Design of concrete structures, (Vol. 2). New York, NY, USA: McGraw-Hill Education.

• GEORGALI, B., and TSAKIRIDIS, P. 2005. Microstructure of fire-damaged concrete. A case study, Cement and Concrete composites, 27, 255-259.

• Handoo, SK, S Agarwal, and SK Agarwal. 2002. Physicochemical, mineralogical, and morphological characteristics of concrete exposed to elevated temperatures, Cement and Concrete Research, 32: 1009-18.

• Hassan, Maryam Abdul Jabbar, Amer Farouk Izzet, and Nazar K Oukaili. 2020. Structural Performance Under Monotonic Static Loading of Reinforced Concrete Gable Roof Beams with Multiple Web Openings, International Journal of Civil Engineering: 1-20.

• Izzat, A. F., 2015. Retrofitting of Reinforced Concrete Damaged Short Column Exposed to High Temperature, Journal of Engineering, 21(3), 34-53.‏

• Kodur, VKR, and Ankit Agrawal, 2016. An approach for evaluating residual capacity of reinforced concrete beams exposed to fire, Engineering Structures, 110: 293-306.

• Lee, Jaesung, Yunping Xi, and Kaspar Willam. 2008. Properties of concrete after high-temperature heating and cooling, ACI Materials Journal, 105: 334.

• Mansur, M. A., Huang, L. M., Tan, K. H., and Lee, S. L., 1992. Deflections of Reinforced Concrete Beams with Web Openings, ACI Structural Journal, V. 89, No. 4, 1992.

• Mohammed, S. D., and Fawzi, N. M., 2016. Fire Flame Influence on the Behavior of reinforced Concrete Beams Affected by Repeated Load. Journal of Engineering, 22(9), 206-223.

• Carino, N. J., and Clifton, J. R., 1995. Prediction of Cracking in Reinforced Concrete Structures, Building and Fire Research Laboratory, National Institute of Standards and Technology, 1995.

• Tufail, Muhammad, Khan Shahzada, Bora Gencturk, and Jianqiang Wei, 2017. Effect of elevated temperature on mechanical properties of limestone, quartzite and granite concrete, International Journal of Concrete Structures and Materials, 11: 17.

• WANG, Z.-H., and TAN, K. H., 2006. Residual area method for heat transfer analysis of concrete-encased I-sections in fire. Engineering Structures, 28, 411-422.

• WICKSTROM, U., 1986. A very simple method for estimating temperature in fire exposed concrete structures. Technical Report SP-RAPP ,45, Swedish National Testing Institute.



How to Cite

Abdulkareem, B. and Izzet, A. F. (2022) “Serviceability of Post-fire RC Rafters with Openings of Different Sizes and Shapes”, Journal of Engineering, 28(1), pp. 19–32. doi: 10.31026/j.eng.2022.01.02.