Reinforcement structure for slab shear-vulnerable sections in pilotis buildings and buildings equipped with the same

Reinforcement structure for preventing cracks in thin pilotis slabs using unit-type shear reinforcement hooked onto upper reinforcing bars

This technology is a reinforcement structure for slab sections vulnerable to shear loads in pilotis buildings. It features reinforcing bars placed alongside horizontal and vertical main bars in slabs where upper and lower walls are misaligned, with unit-type shear reinforcement hooked onto these reinforcing bars and installed vertically through the slab.

In low-rise pilotis multi-family housing, floor plans often change between levels, causing upper and lower walls to be misaligned out-of-plane. This concentrates shear force and bending moments on the slabs, a vulnerability highlighted by the damage observed during the Pohang earthquake. Existing slab shear reinforcement is mostly designed for slabs thicker than 250mm, making it difficult to use in thinner slabs. Furthermore, because these methods constrain both upper and lower bending bars, they suffer from poor constructability due to complex rebar arrangements and increased construction time and costs caused by secondary processes like welding and cutting.

This technology creates a connecting loop by using a hooked rebar that wraps around the reinforcing bar at an angle, with its end bent to support the underside of the reinforcing bar. Vertical reinforcement and horizontal reinforcement placed next to the lower horizontal main bars are then attached in a ┻ or ┗┛ shape. Alternatively, multiple diagonal bars and horizontal reinforcement can be bundled with a connecting bar to form an isosceles triangle shape when viewed from the front, with the connecting bar secured to the horizontal main bars. Applicable to low-to-mid-rise pilotis multi-family housing, first-floor parking-type neighborhood facilities, and seismic retrofitting of existing pilotis buildings, this system allows for shear reinforcement in slabs thinner than 250mm simply by hooking it onto the upper bars, thereby reducing premature shear failure in wall-misaligned sections.

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Key Features:

• Horizontal main bars placed at the top and bottom of the slab to intersect with the staggered upper and lower walls
• Reinforcing bars placed on top of the horizontal main bars in the slab between the upper and lower walls, arranged parallel to the vertical main bars
• A connecting loop including a hooked rebar that wraps around the reinforcing bar at an angle and a catch rebar bent from the hooked rebar to support the bottom of the reinforcing bar
• Shear reinforcement consisting of vertical reinforcement connected to the connecting loop and horizontal reinforcement placed adjacent to the horizontal main bars at the bottom of the slab

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This invention was developed with support from the Ministry of Education's Safety and Health Convergence Technology Research Institute.

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