CUMULATIVE CYCLIC DEFORMATION CAPACITY OF TUBULAR MEMBERS WITH MORTAL IN-FILLED TUBULAR BUCKLING RESTRAINER

Abstract

Tubular sections are commonly used for truss structures or diagonal braces, because they have higher moment-of-inertia comparing to H-sections or L-sections with the same area. However, their cumulative cyclic deformation capacity after buckling is known as quite small, because high strain concentration appears at local elbow buckling. To improve the performance of such members, the authors have proposed retrofit method to add outer tube and in-filled mortar in-between, as buckling restrainer. In this paper, cumulative cyclic deformation capacity of this member is researched by cyclic loading tests with various thickness ratios and strain amplitudes. Their strain concentration mechanism is also researched thorough various analyses, followed by proposing the concept of strain concentration index. The easy evaluation method for cumulative deformation capacity and energy dissipation capacity is proposed using this index.