Precast, prestressed hollow core slabs offer the designer an economical solution for a floor or roof system, where uniform load conditions coupled with large spans dictate the design. However, in cases of large concentrated loads, the shear capacity of the slabs may be exceeded. Based on previous testing and analysis, it is believed that the American and Canadian concrete design codes yield unduly conservative shear designs for precast/prestressed hollow core slabs in the 203 to 305 mm depth range. Tests performed on hollow core slabs in Europe demonstrated that the European code was inaccurate in the prediction of web-shear resistance of hollow core slabs. The objective of this research program is to develop equations that more accurately predict the shear capacity of hollow core slabs, through testing a series of hollow core slabs to failure in shear. The overall program consists of two phases. Phase 1 of the program involves testing a total of twelve hollow core slabs from one slab producer, using 2 types of extruders. Phase 2 of the program includes an additional twelve hollow core slabs, from two separate slab producers, using several types of extruders. The focus of this paper is on the results of the first four slabs tested in Phase 1. The test variables include the length of bearing and the level of prestressing. Results are presented in terms of actual to predicted capacity according to the American and Canadian concrete design codes, and the mode of failure.
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