# Study on Shear Performance of Short Bol Interface in ECC-Steel Bridge Deck Composite Structure
## 3 Results and Discussions
### Load-Slip Relationship  
Table 5 shows the main results of the test, and for the convenience of comparative study, the load-slip curves of each specimen are classified and arranged as shown in Figure 6. The interaction between the peg and the ECC layer is not a linear process, and the curve can be roughly divided into an elastic stage, an elastoplastic stage and a plastic stage. In the elastic stage, both the stud and the ECC layer are in a linear elastic state, and it is believed that the shear stiffness of the stud remains unchanged at this time; in the elastoplastic stage, the stiffness of the stud is significantly greater than that of the ECC structural layer. The ECC under the root of the stud is compressed and enters the plastic stage, so the dominant load-displacement curve presents a nonlinear change. It grows again until the stud shears and the member fails. Figure 6a-d show that when the diameter and spacing of the pegs are constant, the bearing capacity of the member is basically proportional to the height of the pegs; when the pegs have smaller diameters (13 mm and 16 mm in diameter), the shear-bearing capacity of the specimens with different stud heights is not much different, which shows that when the length and diameter of the short stud are relatively large, it has little effect on the  
Figure 5: The damage of the specimen: (a) Steel plate surface; (b) ECC surface. shear-bearing capacity of the ECC-steel plate composite member. However, when the stud diameters are 19 mm and 22 mm, and the stud spacing is constant, the shear-bearing capacity of the specimen increases obviously with the increase in the stud height. Since the longitudinal number of studs is too small to exert the influence of stud spacing, this test cannot demonstrate the effect of stud spacing on the bearing capacity. Figure 6e-h show that the ultimate bearing capacity of components with different stud diameters increases significantly as the stud diameter increases. The specimen with a stud diameter of 22 mm is stronger than the specimen with a stud diameter of 13 mm. The bearing capacity of the stud is increased by about 49% on average, and the larger the diameter of the stud, the smaller the relative slip value under the same horizontal load. When the diameter and length of the stud are constant, it can be seen from the comparison of the specimens with different diameters that the individual load-slip curves are lower than the expected level due to the fracture of the short stud weld, which shows the importance of the stud welding quality to its bearing capacity. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Symbol** & **Fmax/kN** & **P\({}_{\text{u}}\)/kN** & **\(\delta_{\text{max}}\)/mm** & **Destruction Form** \\ \hline STUD1 & 335.2 & 41.9 & 3.7 & Pins sheared, unilateral damage \\ STUD2 & 331.4 & 43.9 & 3.4 & Pins sheared, bilateral damage \\ STUD3 & 329.0 & 41.1 & 3.61 & Pins sheared, unilateral damage \\ STUD4 & 342.0 & 42.7 & 3.32 & Pins sheared, unilateral damage \\ STUD5 & 327.3 & 40.9 & 3.1 & Pins sheared, unilateral damage \\ STUD6 & 327.0 & 40.8 & 3.1 & Pins sheared, bilateral damage \\ STUD7 & 353.1 & 44.1 & 2.4 & Pins sheared, unilateral damage \\ STUD8 & 333.6 & 41.7 & 2.8 & Pins sheared, bilateral damage \\ STUD9 & 386.9 & 48.3 & 2.4 & Weld sheared, unilateral damage \\ STUD10 & 376.5 & 47.0 & 2.51 & Pins sheared, unilateral damage \\ STUD11 & 401.4 & 50.1 & 2.2 & Weld sheared, bilateral damage \\ STUD12 & 360.5 & 45.0 & 2.7 & Pins sheared, unilateral damage \\ STUD13 & 520.3 & 65.0 & 2.22 & Weld sheared, unilateral damage \\ STUD14 & 381.1 & 47.6 & 2.1 & Pins sheared, unilateral damage \\ STUD15 & 562.0 & 70.0 & 2.0 & Weld sheared, unilateral damage \\ STUD16 & 411.0 & 51.3 & 2.43 & Pins sheared, unilateral damage \\ \hline \hline \end{tabular} Note: F\({}_{\text{max}}\) is the maximum load of the test loading; P\({}_{\text{u}}\) is the shear bearing capacity of a single short peg \(\delta_{\text{max}}\) is the maximum slip measured by the test loading.  
\end{table} 
Table 5: Main results of the test.