Evaluation of Cracking and Serviceability Performance of Lightweight Aggregate Concrete Deep Beams
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pISSN 1226-7988, eISSN 1976-3808 www.springer.com/12205
DOI 10.1007/s12205-020-1985-y
Structural Engineering
Evaluation of Cracking and Serviceability Performance of Lightweight Aggregate Concrete Deep Beams Hui Weia, Tao Wua, Lixin Suna, and Xi Liua School of Civil Engineering, Chang’an University, Xi’an 710061, China
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ARTICLE HISTORY
ABSTRACT
Received 4 November 2019 Accepted 7 July 2020 Published Online 17 September 2020
This paper investigated the diagonal crack propagation and serviceability performance of fifteen deep beams fabricated using lightweight aggregate concrete (LWAC). Experimental variables included the shear span-depth ratio, beam section depth, and bearing plate width. The test results were reported in terms of crack propagation, diagonal crack width, diagonal cracking load, and size effect on the serviceability of deep beams; they were also employed to establish a relationship between residual shear bearing capacity and maximum diagonal crack width for such components. In addition, the crack width limits in current code provisions were utilized to further evaluate the serviceability of LWAC deep beams. The test results revealed that the diagonal crack propagation is almost independent of the variation of beam depth, while the diagonal crack width exhibited an obvious increasing trend as shear span-depth ratio or bearing plate width increased. At service load level, the crack width limit of 0.4 mm stipulated in ACI 224-R-01 can be satisfied by LWAC deep beams with horizontal and vertical shear reinforcement ratios more than 0.3%.
KEYWORDS Lightweight aggregate concrete Deep beams Serviceability Diagonal cracking Service load
1. Introduction Lightweight aggregate concrete (LWAC) with several advantages, including lower density, excellent thermal insulation, and superior durability, has extensive applications as a building material (Zhang and Gjvorv, 1991; Cui et al., 2012; Wu et al., 2019; Liu et al., 2019). These characteristics make such material well-suited for use in large scale and heavily loaded structural members in high-rise buildings and bridge engineering. In deep beams, LWAC can allow for the reductions in their self-weight and section dimension, which effectively enhance the seismic resistance capacity of reinforced concrete (RC) structures (Yang, 2010; Wu et al., 2018). However, LWAC is prone to undergo the aggregate fracture due to the lower strength of lightweight coarse aggregates compared with the cement matrix, which results in a more brittle shear failure without visible omen experienced by LWAC deep beams. The less contribution of aggregate interlock along the diagonal cracks also has a negative effect on the effectiveness of shear-transfer mechanism of this kind of members, which leading to a degradation of serviceability performance simultaneously. In addition, the service behavior of deep beams is easily decreased owing to the crack propagation caused by the external conditions, CORRESPONDENCE Tao Wu
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ⓒ 2020 Korean Society of Civil Engineer
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