日本神户大学 浅田勇人 助理教授学术报告
报告题目：基于延性断裂力学的新型金属阻尼器提案（Proposals of New Metallic Dampers Based on Ductile Fracture Mechanics）
Dr. Asada is an assistant professor of Department of Architecture at Kobe University from 2011. Prior to this, he was sponsored as a research fellow of JSPS. He received Ph. D from Tokyo Institute of Technology. He is a member of several technical committees of professional organization including AIJ, JCI and JSSC. His research interests include experimental investigation of seismic behavior of steel and steel-concrete composite building structures, analysis of structural systems, and design of connections of steel structures. Currently, his research interests are centered in seismic assessment of existing steel frame systems and the stability performance of steel bracing including connections.
For simplicity, many engineers choose single-shear bolted joints for the end connections of hollow structural section (HSS) braces. When such connections are adopted, the braces may be susceptible to an undesirable buckling mode that involves formation of several plastic hinges within bracing connections. The concerned buckling mode was observed in a number of buildings after the 1995 Kobe earthquake and 2011 Tohoku earthquake, and led to fracture of the connection. Past studies by the authors have alarmed that deformation concentration in the connection results in substantially smaller compressive strength and energy dissipation capacity of braces. Therefore, every care must be taken to avoid the buckling mode that causes deformation concentration at the bracing connections. This study proposes analysis models to derive buckling strength formulae, and verifies the formulae with tests and FEA.
报告题目：Stability Issue of Hollow Structural Section(HSS) Brace with One-lap Bolted Connections
Dr. Liang-Jiu Jia has working on steel structures for more than 10 years. He graduated from The University of Tokyo, and joined Research Institute of Structural Engineering and Disaster Reduction at Tongji University in 2015. He is the author of over 20 international journal papers (including 8 ASCE journal papers), 30 conference and journal papers. His research has been recognized by 13th International Symposium on Tubular Structures and awarded the CIDECT Student Award. He is now in charge of / taking part in several research projects including NSFC and National Key R&D Program of China etc., and he is also active in international cooperation.
Welded steel structures can fail due to either brittle or ductile fracture due to the small number of plastic strain reversals with large amplitudes. It has also been found that the brittle fracture occurring in the 1994 Northridge Earthquake and the 1995 Kobe Earthquake is triggered by preceding ductile fracture. Ductile fracture models based on void growth theory are proposed to evaluate the fracture under cyclic large plastic straining.
In addition, recent strong earthquakes in Japan and New Zealand etc. have served as reminders that several strong aftershocks can occur following the main shock, which puts forward higher demand for seismic performance of metallic dampers. Since metallic dampers also mainly fail due to ductile fracture, and a number of novel high performance metallic dampers are proposed with the assistance of the proposed ductile fracture model.