Small-Scale Tests on Tensile Membrane Action of Reinforced Mortar Slabs at Elevated Temperature
In case of fire, reinforced concrete floor slabs are heated on the lower surface and are deflected due to the temperature gradient along the thickness direction and the reduction in strength at elevated temperature. In accordance with the deflection of the floor slab, the membrane stress developed and caused the enhancement of load-bearing capacity. This paper discussed, in the basis of the results of high-temperature loading tests of small-scale reinforced mortal slabs, the amount of deflection due to the temperature gradient and the influence of the bottom reinforcement temperature on the maximum strength, and the enhancement factor. The parameters include the support conditions and the steel temperature at the bottom reinforcement. The thermal deflection of the two-way slab due to the temperature gradient approximately agreed with the theoretical value of the one-way slab. The maximum load-bearing capacity in case of the bottom reinforcement temperature of 400 °C was equal to or larger than that at room temperature. The decrease in the maximum strength above 500 °C was lower for the two-way slabs than for the one-way slabs. The enhancement of the maximum strength due to tensile membrane action was confirmed from the test result without punching shear failure.
KeywordReinforced mortar slabs Tensile membrane action Fire resistance Thermal deflection High-temperature loading test
Cross-sectional area of the bottom reinforcement (mm2)
Effective depth of the specimen (mm)
Depth of the specimen (mm)
Supporting span (mm)
Collapse load based on the yield line theory for the one-way slab (kN)
Collapse load based on the yield line theory for the two-way slab (kN)
Difference of surface temperature between upper and lower of the slab (K)
- \( \alpha \)
The linear coefficient of expansion (K−1)
The calculated value of thermal deflection at the midspan of the slab (mm)
Allowable stress for temporary loading of the reinforcement (N/mm2)
This work was supported by JSPS KAKENHI Grant Number 15K06285. The authors would like to acknowledge Sansei Giken Co., Ltd. and Egima Co., Ltd. for producing the equipment.
- 2.Bailey, C. G., & Moore, D. B. (2006). The structural behaviour of steel frames with composite floorslabs subject to fire: Part 1: Theory. The Structural Engineer, 78(11), 19–27.Google Scholar
- 4.Franssen, J. (2012). Tensile membrane action in composite floors subjected to fire. In Advances in steel concrete composite and hybrid structures (pp. 125–154). ISBN: 978-981-07-2613-3. https://doi.org/10.3850/978/-981-07-2613-3_p008.
- 5.British Steel plc, Swinden Technology Centre, A European Joint Research Programme: The behaviour of multi-storey steel framed buildings in fire, 1999.Google Scholar
- 6.Zhao, B., Roosefid, M., & Vassart, O. (2008). Full scale test of a steel and concrete composite floor exposed to ISO fire. In Proceedings of the 5th International Conference on Structures in Fire (pp. 539–550).Google Scholar
- 7.Zhang, N. S., Li, G. Q., Lou, G. B., Jiang, S. C., & Hao, K. C. (2009). Experimental study on full scale composite floor slabs under fire condition. In Proceedings of the Application of Structural Fire Engineering (pp. 502–511).Google Scholar
- 8.Stadler, M., & Mensinger, M. (2011). Munich fire tests on membrane action. In Presentation made at Steel In Fire Forum. UK: STIFF.Google Scholar
- 10.Architectural Institute of Japan. (2013). Design recommendations for composite constructions (in Japanese).Google Scholar
- 11.Tokoyoda, M., Yamashita, H., Toyoda, K., Hirashima, T., & Uesugi, H. (2007). An experimental study of transient strain for a concrete with limestone aggregate. In Proceedings of the International workshop on Fire Design of Concrete Structures—From Materials Modelling to Structural Performance, fib (pp. 105–114).Google Scholar