Bar Pullout Tests and Seismic Tests of Small-Headed Bars in Beam-Column Joints


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Title: Bar Pullout Tests and Seismic Tests of Small-Headed Bars in Beam-Column Joints

Author(s): Thomas H.-K. Kang, Sang-Su Ha, and Dong-Uk Choi

Publication: Structural Journal

Volume: 107

Issue: 1

Appears on pages(s): 32-42

Keywords: bar; cyclic loading; embedment length; joint; pullout; seismic.

Date: 1/1/2010

Experimental research was performed to evaluate the applicability of headed bars with small heads in exterior beam-column joints. A total of 12 pullout tests were first performed to examine anchorage behavior of headed bars subjected to monotonic and repeated loading, with test variables such as the head size, shape, and headattaching technique. Reversed cyclic tests of two full-scale exterior beam-column joints were subsequently conducted to assess seismic performance. The pullout test results revealed that all types of heads and head-attaching techniques performed almost equally well, while the seismic test results indicated that the joint using small-headed bars showed better seismic performance than the joint using hooked bars in terms of damage extent, joint behavior, lateral drift capacity, and energy dissipation. In particular, the joint with headed bars generally satisfied ACI 374 acceptance criteria. These experimental results demonstrate that small-headed bars perform well with a development length shorter than that needed for hooked bars, and they can be effectively anchored in exterior beam-column joints under inelastic deformation reversals.