BENDING CAPACITY OF PRECAST PRESTRESSED HOLLOW CORE SLABS WITH CONCRETE TOPPINGS
DOI:
https://doi.org/10.11113/mjce.v20.15770Keywords:
Hollow core slabs, In-situ concrete toppings, Composite action, Bending capacity, Interface slipAbstract
This paper presents the effect of surface roughness (smooth and rough) and surface condition (ponded and optimum wet) on the bending capacity of precast prestressed hollow core slabs with in-situ concrete toppings by a series of full-scale experimental tests. Interface slip was also measured throughout the test to observe the composite behaviour of the test specimens. The tests result show that the ultimate bending capacity for the ponded condition for the smooth and rough surfaces was 3 to 5% less than that of the optimum wet even though they were still higher than the calculated values. A slip of 0.08 mm was observed for the smooth-ponded specimen. It was later found that by roughening the top surface of the precast prestressed hollow core slab, full composite action can be achieved if the interface slip is reduced or eliminated. A theoretical method to predict the deflection with partial interaction is also presented in this paper based on the experimental strain gradient. From the theoretical approach, the findings suggest that an interface slip still may had occurred near the mid-span region although it was not detected by the slip gauge located at both ends of the specimen.References
Ajdukiewicz, A. B., Kliszczewicz, A. T., et al. (2007). Behaviour of Pre-tensioned Hollow Core Slabs with In-situ Concrete Topping. FIB Symposium: Concrete Structures - Simulators of
Development. Structural Engineering Conferences (SECON), Dubrovnik, 459-466.
Bensalem, K. (2001). The Structural Integrity of Precast Concrete Floor Systems Used as Horizontal Diaphgrams. Ph.D Thesis, University of Nottingham, Nottingham.
British Standard Institute (BSI) (1985) BS 8110: Part 2: 1985. Structural Use of Concrete - Part
: Code of Practice for Special Circumstances. London.
British Standard Institute (BSI) (1988) BS 1134: Part 1: 1988. Assessment of Surface Texture - Part 1: Methods and Instrument. London.
Elliott, K. S. (2002). Precast Concrete Structures. Oxford: Butterwoth-Heinemann Publications.
Federation Internationale de la Precontrainte (FIP) (1982) FIP Guide to Good Practice - Shear at the Interface of Precast and In-situ Concrete. Wrexham Springs. Girhammar, U. A. and Pajari, M. (2008). Tests and Analysis on Shear Strength of Composite Slabs
of Hollow Core Units and Concrete Topping. Construction and Building Materials. 22: 1708-1722.
Gohnert, M. (2000). Proposed Theory to Determine the Horizontal Shear Between Composite Precast and In-situ Concrete. Cement and Concrete Composites. 22 (6): 469-476.
Gohnert, M. (2003). Horizontal Shear Transfer Across a Roughened Surface. Cement and Concrete Composites. 25 (3): 379-385.
Ibrahim, I. S. and Elliott, K. S. (2006). Interface Shear Stress of Hollow Core Slabs with Concrete Toppings. Sixth International Conference on Concrete Engineering and Technology
(CONCET 2006). Institution of Engineers Malaysia, Kuala Lumpur, 104-116.
Lam, D., Elliott, K. S., et al. (2000). Designing Composite Steel Beams with Precast Concrete Hollow-Core Slabs. Proceedings of the Institution of Civil Engineers: Structures and
Buildings. 140: 139-149.
Ros, P. S., Cabo, F. D., et al. (1994). Experimental Research on Prestressed Hollow Core Slabs Floors with Insitu Concrete Topping. FIP 12th International Congress. Federation
Internationale de la Precontrainte, Washington, C33-C41.
Santos, P. M. D., Julio, E. N. B. S., et al. (2007). Correlation Between Concrete-to-concrete Bond
Strength and the Roughness of the Substrate Surface. Construction and Building Materials. (21): 1688-1695.
Scott, N. L. (1973). Performance of Precast Prestressed Hollow Core Slab with Composite Concrete Topping. PCI Journal. 18 (2): 64-77.
Ueda, T. and Stitmannaithum, B. (1991). Shear Strength of Precast Prestressed Hollow Slabs with Concrete Topping. ACI Structural Journal. 88 (4): 402-410.
Walraven, J. C. (1991). Theoretical Aspects of Composite Structures. Netherlands, University of
Technology Delft.
