Improvement of the deformation capacity o the column-to-beam joint by the reinforce welding method around the scallop bottom

Abstract

Improvement of deformation capacity for a column-to-beam joint is an important theme for improving the earthquake-resistance performance of building structures. One of the causes of decreasing deformation capacity is the existence of stress concentration against the beam flange by the scallop (access hole). The non-scallop method is generally recommended to improve this problem, but it has a large disadvantage in that it is not able to apply to the on-site joint process. The reinforce welding method around the scallop bottom has been developed to be able to apply to an on-site joint and obtain better performance than the non-scallop method. The improved mechanism is a combination of: (1) decreasing the stress concentration; (2) increasing effective thickness; and (3) increasing total length of the breaking line. The deformation capacity by the reinforce welding method around the scallop bottom is a maximum 3.2 times that for the conventional scallop method in the reverse repeating bend test using an actual structure with a beam flange of 19 mm thickness and 490 N mm⁻² class steel. This improving effect is better than the non-scallop method.

Keywords:

• Scallop
• access hole
• plastic deformation
• arc welding
• stress concentration
• column-to-beam joint
• building

Notes

Presented at National Conference, Autumn 2013

Selected from Quarterly Journal of the Japan Welding Society 2014 32(2) 73–82