Abstract

This paper investigated the bond behavior of deformed steel bars in self-compacting concrete (SCC). Specimens with different concrete compressive strength (18.4 MPa, 27.0 MPa, and 35.6 MPa), concrete cover size (2.0 Φ, 3.0 Φ, 4.2 Φ, and 5.0 Φ), and embedded length (3.0 Φ, 4.0 Φ, 5.0 Φ, and 6.0 Φ) were prepared and tested under pull-out loading. The bond stress distribution for deformed steel bars in SCC was tentatively explored by specimens with inserted steel strain gauges. Results show that the bond strength between reinforcing bars and SCC increased with the increasing concrete grades and concrete cover depth, while specimens with lower embedded length showed higher bond strength. The larger concrete cover size and transverse reinforcements can provide effective restraint and further change the failure pattern from splitting failure to pull-out failure. The unevenness of bond stress distribution between SCC and steel bars was intensified as the embedded length increased. Compared with test results, existing empirical and code models for bond strength prediction in normal vibrated concrete were all conservative and can be extended for SCC.

摘要

本文研究了变形钢筋在自密实混凝土 (SCC) 中的粘结行为。具有不同混凝土抗压强度（18.4 MPa、27.0 MPa 和 35.6 MPa）、混凝土保护层尺寸（2.0 Φ、3.0 Φ、4.2 Φ 和 5.0 Φ）和嵌入长度（3.0 Φ、4.0 Φ、5.0 Φ 和6.0 Φ) 在拉出载荷下制备和测试。SCC 中变形钢筋的结合应力分布通过带有插入钢应变片的试样进行了初步探索。结果表明，钢筋与 SCC 之间的粘结强度随着混凝土等级和混凝土覆盖层深度的增加而增加，而嵌入长度较小的试件表现出较高的粘结强度。较大的混凝土保护层尺寸和横向钢筋可以提供有效的约束，并进一步将破坏模式从分裂破坏转变为拉拔破坏。随着埋入长度的增加，SCC与钢筋之间结合应力分布的不均匀性加剧。与试验结果相比，现有的普通振动混凝土粘结强度预测的经验模型和代码模型都是保守的，可以扩展到 SCC。