現場溶接型梁端仕口ディテールが先組みビルトH梁を用いた柱梁溶接接合部の変形能力に及ぼす影響に関する実験的研究

Abstract

This paper deals with beam-end details of non-scallop method for field welding. The welding position of the lower flange in field welding is downward, the scallop construction method is generally used as the non-scallop construction method is difficult. The stress concentration occurs at the bottom of scallop, therefore brittle fracture of the beam end flange from the bottom of scallop is frequently reported. For that reason, joint types for preventing premature fracture from the bottom of scallop have been proposed. For example, those are horizontal haunch method, perforated flange method, etc. However, these joint types show sufficient deforming capacity, but in many cases volume of steel and processing cost increase. The purpose of this study is to propose welding non-scallop construction method filling the holes of scallops in field welding in order to eliminate stress concentration at bottom of scallop by changing the shapes of scallop parts. In this paper, filling welding construction method and inserting fillet construction method are used. It is clarified beam end details that improve deformation capacity of field welding beam-to-column joint with pre-built-up H-shaped beam. Full scale tests were carried out. The results obtained here are shown below. 1) Method to fill a column and the gap of beam-web by using welded joint (BM_L_W specimen, shown in Fig. 1c-3)) and to weld fillet weld diaphragm and billet (BS_P65 specimen, shown in Fig. 1b-2)) were most suitable as beam-end details improved deformation capacity of beam-to-column connections with field welding. 2) Cumulative plastic deformation ratio (shown it as follows with ηs) of BM_L_W specimen was 8.2, and the value of ηs exceeded deformation capacity of shop welding non-scallop method (shown in Fig. 13). Also, rate of increase in strength (shown it as follow with α) of BM_L_W specimen was 1.48. When it consider the restriction effect by diaphragm, strength of beam-end flange fracture reached tensile strength of base metal. From this, the stress concentration in a scallop bottom disappeared, and fracture origin shifted to end-tab. 3) ηs of BS_P65 specimen was 6.4, and at the same level as deformation capacity of shop welding non-scallop method (shown in Fig. 13). A of BS_P65 specimen was 1.40. As well as BM_L_W specimen, strength of beam-end flange fracture to the same level as base material toughness. 4) Deformation capacity of beam-end details which stress concentration remained behind in scallop bottom (BS_P50, BM_F and BM_L specimens) decreased in comparison with its BS specimen (shown in Fig. 13).