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. 2025 Jun 22;18(13):2950.
doi: 10.3390/ma18132950.

Anchorage Performance of an Innovative Assembled Joint with Large-Diameter Steel Bar Grout Lapping in Concrete Reserved Hole

Qi Chen  1 , Xiaoyong Luo  1   2 , Chao Deng  1 , Tai Zhou  1 , Xutong Zheng  1
Affiliations

Anchorage Performance of an Innovative Assembled Joint with Large-Diameter Steel Bar Grout Lapping in Concrete Reserved Hole

Qi Chen et al. Materials (Basel). .

Abstract

To investigate the anchorage performance of an innovative assembled joint with large-diameter steel bar grout lapping in a concrete reserved hole, the effects of anchorage length and high-strength grouting material types on the failure mode, load-displacement curve, ultimate bond strength and strain variation were analyzed through the pull-out tests of 15 specimens. On this basis, the calculation formulae of critical and ultimate anchorage length were established and the applicability was verified, and then the recommended value of minimum anchorage length was provided. The results showed that the failure modes included splitting-steel bar pull-out failure and UHPC-concrete interface failure. With the increase in anchorage length, the bond strength showed a trend of increasing first and then decreasing. Increasing the grouting material strength can effectively improve the bond performance. When the anchored steel bar is HRB400 with a diameter not less than 20 mm, the recommended minimum anchorage length is 15.0d~18.3d. When the grouting material strength is larger than or equal to 100 MPa, the anchorage length should not be less than 15.0d.

Keywords: anchorage length; anchorage performance; assembled joint; high-strength grouting material; large-diameter steel bar; pull-out test.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
The schematic diagrams of joint: (a) large-diameter steel bar grout lapping in reserved hole; (b) spiral stirrup grout splicing connection.
Figure 2
Figure 2
Design of specimens (unit: mm): (a) three-dimensional view; (b) geometric dimensions and construction.
Figure 3
Figure 3
Manufacturing process of specimens.
Figure 4
Figure 4
Process of material performance testing: (a) material performance testing of steel bar; (b) material performance testing of concrete, SCC, UHPC and BSGM.
Figure 5
Figure 5
Pull-out test system: (a) three-dimensional view; (b) photographic image.
Figure 6
Figure 6
Failure mode of specimens: (a) 5d/10d/15d-Z; (b) 10d-U; (c) 10d-D.
Figure 7
Figure 7
Internal damage of specimens: (a) 10d-Z; (b) 10d-U; (c) 10d-D.
Figure 7
Figure 7
Internal damage of specimens: (a) 10d-Z; (b) 10d-U; (c) 10d-D.
Figure 8
Figure 8
Load–displacement curves at loading end and free end: (a) 10d-Z-3; (b) 15d-Z-3.
Figure 9
Figure 9
Load–displacement curves: (a) 5d-Z; (b) 10d-Z; (c) 15d-Z; (d) 10d-U; (e) 10d-D.
Figure 10
Figure 10
Variation curves of bond strength: (a) effect of anchorage length; (b) effect of grouting material.
Figure 11
Figure 11
Variation curves of strain: (a) 5d-Z; (b) 10d-Z; (c) 15d-Z; (d) 10d-U; (e) 10d-D.
Figure 12
Figure 12
Fitting curve.
See this image and copyright information in PMC

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