Title: Benefits of Fiber Addition on the Seismic Resistance of RC Joints

Author(s): A.E. Naaman

Publication: Symposium Paper

Volume: 311

Issue:

Appears on pages(s): 1-12

Keywords: damage tolerance, energy absorption, fiber reinforced concrete, high performance, precast prestressed elements, reinforced concrete frames, seismic resistant joints, SIFCON, strain hardening, strain softening, toughness

DOI: 10.14359/51689320

Date: 9/1/2016

Abstract:
This paper provides a brief overview of a project comprising several parts, carried out in collaboration with Jim Wight and a number of graduate students over a period of about fifteen years, starting in the mid 1980’s. The project focused on the effects the addition of fibers can have on the performance of reinforced concrete joints. Lessons learned from early “non-success” and subsequent successes achieved are described. Although details of the effects of fiber reinforcement on the joint behavior under monotonic and cyclic loading such as load carrying capacity, hysteretic moment-rotation response, strength and stiffness degradation, shear resisting mechanisms, and absorbed energy are left to the references cited, a key observation related to the hysteretic energy dissipated is emphasized. It is observed in particular that not all fibers provide equal benefits and the fiber reinforcing parameters must be carefully selected in order to achieve superior results. Two important factors are further stressed: the need to achieve a fiber reinforced concrete composite that is strain hardening in tension (thus likely in shear as well), and the need to develop a postcracking resistance that remains significant even when crack widths exceed the millimeter range.