This technology is an anchorage reinforcement structure that connects a ductile rod—designed to induce ductile failure—longitudinally to the top of an anchor embedded in a concrete member through a base plate, then covers it and secures it with a rod fastener.
Current building design standards require an elongation length of at least eight times the anchor diameter to ensure ductile failure of the steel occurs before brittle failure of the concrete under high seismic loads. However, many existing anchors lack this required length. Increasing the number of anchors to compensate for insufficient seismic capacity is often cumbersome and costly.
This technology features a ductile rod with an open-bottom hollow core for anchor insertion. The internal threads at the bottom of the hollow core connect to the exposed anchor, while the external threads at the top connect to a rod fastener, with a chamfer formed at the top of the hollow. The installation holes in the base plate and cover are larger than the anchor to maintain clearance, and the ductile rod matches the anchor's cross-section and outer diameter. Applicable to seismic retrofitting of equipment and piping anchors in aging buildings, plant machinery foundations, and non-structural element remodeling, it converts existing anchors into ductile, elongated ones without removal or additional drilling, preventing sudden concrete failure during earthquakes.
This invention was developed with support from the Ministry of Land, Infrastructure and Transport for the development of seismic performance evaluation and reinforcement design technology for steel plants.
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