| CPC B23K 26/342 (2015.10) [E01D 22/00 (2013.01); E04G 23/0203 (2013.01)] | 2 Claims |

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1. A crack repair method for an existing steel structure that repairs a crack generated in the existing steel structure by using a filler material, the crack repair method comprising:
a build-up welding step of performing build-up welding by arc welding or laser welding using the filler material on the crack generated in the existing steel structure to form a filler material build-up portion; and
a laser beam piercing welding step of performing piercing welding by irradiating the filler material build-up portion with a laser beam such that a welding-repaired portion, in which the filler material build-up portion is melted, is formed around the crack.
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