Abstract
The prestressed hollow-core slab (PHCS) is a precast concrete member that can maximize productivity and structural performance efficiency of concrete cross-section. For the PHCS members produced by extrusion method, however, it is difficult to provide the shear reinforcement due to its unique production method to form the hollow-cores in concrete section. The recently revised ACI318 Building Code Requirements stipulate that web-shear capacity of thick hollow-core member over 315 mm depth without the minimum shear reinforcement should be reduced in half, which may result in an excessively conservative shear design for the PHCS member compared to conventional prestressed concrete members with thin webs. In this study, shear tests on PHCS members, which have typical thicknesses widely used in precast construction industry, were conducted, and a large number of shear test data were additionally collected from previous studies to evaluate the current shear design criteria for PHCS in detail.
Highlights
The prestressed hollow-core slabs (PHCS) have multiple hollows in concrete web, as shown in Fig. 1, which enables to save concrete materials and to be lightweight
This study evaluates the rationality of the reduction in the web-shear strength of the thick PHCS without shear reinforcement in the ACI318 code, and a simple alternative method is presented considering a proper margin of safety and the economic efficiency
Α fse fct where Q is the first moment about the centroidal axis of the part of the cross-sectional area lying farther from the centroidal axis than the point where the shear stresses are being calculated, Ig is the moment of inertia of the gross section, bw is the sum of the total web widths of the PHCS, fct is the tensile strength of the concrete, α is the coefficient for the reduced effective prestress at the critical section, fse is the effective prestress, and Aps and Ag are the cross-sectional area of tendon and concrete, respectively
Summary
The prestressed hollow-core slabs (PHCS) have multiple hollows in concrete web, as shown in Fig. 1, which enables to save concrete materials and to be lightweight. Shear tests were conducted on the PHCS members with various thicknesses ranged from 200 to 500 mm, which is widely used in precast construction industry, and a large number of the web-shear capacity data of PHCS members were collected from previous studies (Pajari 2009; Palmer and Schultz 2010, 2011; Hawkins and Ghosh 2006; Lee et al 2014; Im et al 2014; Walraven and Mercx 1983; Becker and Buettner 1985; Pajari 2005; TNO 2005; Bertagnoli and Mancini 2009; Celal 2011; Rahman et al 2012; Simasathien and Chao 2015) On this basis, this study evaluates the rationality of the reduction in the web-shear strength of the thick PHCS without shear reinforcement in the ACI318 code, and a simple alternative method is presented considering a proper margin of safety and the economic efficiency
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