Reinforced Concrete One-Way Slabs with Large Steps

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Title: Reinforced Concrete One-Way Slabs with Large Steps

Author(s): Thomas H.-K. Kang, Sanghee Kim, Seongwon Hong, Geon-Ho Hong, and Hong-Gun Park

Publication: Structural Journal

Volume: 114

Issue: 04

Appears on pages(s): 899-909

Keywords: crack pattern; moment strength; one-way slab; step; structural performance; supplementary reinforcement

Date: 7/1/2017

Abstract:
To evaluate the performance of relatively large steps in reinforced concrete one-way slabs in terms of the flexural behavior of the stepped slabs, a total of 12 specimens with various shapes of steps and different reinforcing details in steps were tested. The primary purpose of this research is to investigate the structural behavior of one-way slabs with steps and to evaluate the performance of steps in slab depending on various details. In comparing the conventional one-way slab with the stepped slab, it was found that: 1) the specimen without supplementary reinforcement in the step showed a very low moment strength and significant damage; 2) the specimens with diagonal reinforcement in the step exhibited substantial early cracks, experienced hinging of the step, and demonstrated a substantial loss of moment strength; and 3) the specimens with a combination of U-bars, inverted U-bars, L-bars, and inverted L-bars performed very well, reaching almost 100% of moment strength of the one-way slab. The U-bars and inverted U-bars were effective in controlling the diagonal cracks, while the L-bars and inverted L-bars were effective in preventing yielding of the slab reinforcement near the step. Based on the crack pattern and the analysis of the structural performance, the design guidelines of reinforcement details of stepped slabs were proposed.