Title: Influence of High-Strength Reinforcing Bars on Seismic Safety of Concrete Frames

Author(s): Kuanshi Zhong, Wassim M. Ghannoum, and Gregory G. Deierlein

Publication: Structural Journal

Volume: 118

Issue: 5

Appears on pages(s): 299-311

Keywords: collapse safety; concrete special moment frame; high-strength reinforcing bar; reinforcement fatigue and fracture; seismic design

DOI: 10.14359/51732865

Date: 9/1/2021

Abstract:
High-strength longitudinal reinforcement can benefit the constructability and economy of concrete structures but concerns regarding the ductility and fatigue resistance have delayed its applications for seismic design. To evaluate the influence of reinforcement fracture on building seismic safety, a new damage model is developed using available data from reinforcement and member tests, and is employed with nonlinear dynamic analyses to assess and compare the seismic performance of concrete special moment frames with Grade 80 and 100 bars to frames with Grade 60 bars. The bar fracture and structural collapse risks are shown to depend on the bar yield strength, tensile-to-yield strength ratio (T/Y), and bar slenderness (s/db) between lateral ties. Frames with Grade 80 and 100 bars (T/Y ≥ 1.2; s/db ≤ 5) have comparable performance to frames with Grade 60 bars, where bar fracture probabilities are less than approximately 10% in frames (with maximum story drift ratios up to 0.04).