# Study on Shear Performance of Short Bol Interface in ECC-Steel Bridge Deck Composite Structure
## 4 Conclusions  
In this work, 16 push-out specimens were designed and fabricated, and the parameters of failure mode, load-relative slip, stud strain, ECC surface strain, steel bar strain, steel plate strain and interface gap were tested and observed. The conclusions of this work are as follows:  
1. The load-slip curves of ECC-bolt composite specimens have common characteristics, and the curves can be roughly divided into the elastic stage, elastoplastic stage and plastic stage. The short stud is used as a force-transmitting connector in the ECC plate, and the shear force between the steel plate and the ECC mainly produces two failure modes, namely, the shearing of the bolt and the shearing of the weld at the root of the stud. The ECC plate has a local crushing area at the root of the interface stud, and no large cracks are generated in the rest area, which reflects the characteristics of high ductility.
2. The shear bearing capacity of short studs in ECC was significantly affected by the stud diameter, while it was less affected by the stud height and spacing. The larger the diameter of the stud, the greater the shear capacity, but the relative slip of the peak value decreases with the increase in the diameter, that is, the ductility of the component decreases relatively. For peg members of the same diameter, the ultimate bearing capacity is slightly larger if the spacing between the pegs is slightly smaller.
3. The stud load-strain curve exhibits a two-segment linear relationship, and there is no transition segment. Therein, increasing the height of the pegs increases the bearing capacity and increases the ductility of the pegs.
4. The height of the stud has an important influence on the force on the surface of the ECC board. The longer the peg, the greater the tensile stress on the ECC surface; the shorter the peg, the more inclined the ECC plate is to be compressed eccentrically; and the longer the peg, the more inclined to be compressed axially.
5. For this work, the best load capacity of the specimen with 22 mm diameter, 100 mm spacing and 35 mm height of the bolts was found. The parameters studied in this paper are relatively few, and more parameters (such as ECC layer thickness, reinforcement arrangement and weld form) should be considered for the subsequent study on the effect of the shear performance of the pins.  
Conceptualization, C.L. and Z.C.; methodology, Z.C.; validation, Z.Z., S.W. and Y.L. ([PERSON]); formal analysis, Z.Z.; investigation, Y.L. ([PERSON]); re-sources, Z.C. and Z.Z.; data curation, Z.Z. and S.W.; writing--original draft preparation, Z.Z. and Y.L. ([PERSON]); writing--review and editing, Z.C. and Y.L. ([PERSON]); visualization, Y.L. ([PERSON]); supervision, C.L.; project administration, Z.Z.; funding acquisition, Z.C. All authors have read and agreed to the published version of the manuscript.  
Figure 11: Steel–ECC top interface load–gap width curve: (a) 100 mm pitch, 35 mm length studs; (b) 16 mm studs.  
**Funding:** This research was funded by the National Natural Science Foundation of China through Grant No. 51708047, 51778069 and 51978081; the Natural Science Foundation of Hunan Province through Grant No. 2019 JJ50670; and the Excellent youth project of Hunan Provincial Department of Education through Grant No. 19B013.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The data used to support this study are available from the corresponding author upon request.  
**Acknowledgments:** We would like to thank the reviewers for their valuable suggestions.  
**Conflicts of Interest:** The authors declare that they have no conflict of interest.