A Simple Method of Enhancing the Robustness of R/C Frame Structures

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Title: A Simple Method of Enhancing the Robustness of R/C Frame Structures

Author(s): Yihai Bao, H.S. Lew, Fahim Sadek, and Joseph A. Main

Publication: Special Publication

Volume: 309

Issue:

Appears on pages(s): 1-16

Keywords: disproportionate collapse, reinforced concrete, debonding, catenary action, nonlinear finite element analysis

Date: 6/1/2016

Abstract:
A simple debonding technique was proposed to reduce strain localization in reinforcing bars in the region of wide flexural cracks in reinforced concrete (R/C) beams, in order to enhance the resistance of R/C buildings to disproportionate collapse. Debonding was achieved by heat-shrinking polyolefin tube over the reinforcing bar. Results from testing of a No. 8 reinforcing bar showed that with an 8 in (203 mm) debonding length on both sides of a ¼ in (6.35 mm) wide gap, simulating a wide flexural crack, the elongation of the reinforcing bar prior to fracture was about 38 % more than for the case without the debonding technique. This observation demonstrated that the debonding method could effectively reduce strain localization, thereby delaying the fracture of reinforcing bars. To analyze the effects of debonding, detailed finite-element models of the test specimens were developed, which adequately captured the experimental results. R/C frame structures were analyzed by applying the debonding model under a column removal scenario. The results indicated that the debonding method could enhance the development of catenary action in the beams of R/C frame structures.