Modeling of hysteretic behavior & evaluation on the plastic deformation capacity of steel beam-to-column connections under random loading histories

2022 Fiscal Year Final Research Report

• Project/Area Number: 17K14762
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Building structures/Materials
• Research Institution: Tokyo City University
• Principal Investigator: JIAO YU 東京都市大学, 建築都市デザイン学部, 准教授 (40632493)
• Project Period (FY): 2017-04-01 – 2023-03-31
• Keywords: 柱梁接合部 / 繰返し載荷実験 / 数値解析 / 低サイクル疲労 / 歪履歴

Outline of Final Research Achievements

Ductile fracture is one of the most typical steel component failure modes during earthquakes. For most structural steels, the strain-life relationship can be expressed using a Manson-Coffin-type equation. The current study proves whether there is a similar Manson-Coffin relationship between the average flange strain amplitude at the critical cross-section and the number of loading cycles until fracture. Shop welded beam-to-column connections made of 400 N/mm2 class structural steel with conventional or improved types of weld access holes are discussed in this study. Moreover, cyclic in-plane beam analysis is conducted to obtain the strain histories at the beam-end flanges. Based on the strain histories, it is found that, similar to the material level, the Manson-Coffin relationship between the average flange strain amplitude at the critical cross-section and the number of loading cycles until fracture is confirmed on the component level.

Free Research Field

鋼構造の耐震設計

Academic Significance and Societal Importance of the Research Achievements

梁降伏型骨組では、梁端接合部の塑性化により地震入力エネルギーを吸収する。梁端接合部の塑性変形能力を精度良く評価することが、骨組の耐震性能を正確に評価することに結びつく。梁部材の耐震性能を評価する際には、地震動及び構造物の特性を考慮した、振幅が小さいものから振幅が大きいものまで、様々な振幅を持つ載荷履歴の影響を考慮しなければならない。これまで梁の変形性能に関する研究では、変位振幅に着目したものがほとんどであり、本研究では、大振幅から長周期地震動を想定した弾性範囲に近い振幅が小さい繰り返し載荷履歴を受けた鉄骨梁の梁端フランジにおける歪振幅に着目し、歪振幅-繰返し回数（寿命）の関係を解明した。