In-plane shear strength and stiffness of precast concrete panels

Pre-Cast-Panels (PCP) have been used for decades as stay-in-place forms to support the wet concrete during the placement of bridge decks and as part of the composite slab for typical straight bridges. The typical connection detail in Texas is to set the panel on a foam bedding strip, leaving a ledge for the slab concrete to flow under; this ledge provides the long-term support for the panel. The PCP is not structurally connected to the bridge until the slab has set up; it provides no in-plane shear resistance under construction loads, when the superstructure is the most vulnerable to lateral forces. If the PCP is connected to the girders during deck casting they can provide bracing to the top flanges of the beams and forces in the traditional lateral resisting system can be reduced, potentially leading a reduction in the number of cross-frames and top lateral truss member sizes. The objective of this research is to measure the in-plane shear strength and stiffness of PCP attached to girder systems using different connections and to determine the stability of the traditional connection method with respect to in-plane shear movement. The research included testing conventionally reinforced full scale PCP in a shear frame. The typical Texas detail was tested at three different bedding strip heights. Variations of two additional connection methods were tested to determine their behavior. Bolting the PCP to the shear studs provides only a small in-plane shear stiffness and strength. Welding the PCP to a steel shape that is welded to the top flange of the beam provides a much stronger and stiffer connection.