## 3 Test Results and Analysis  
### Failure Pattern  
The failure modes of beam-column connections include flexural failure at the column end, flexural failure at the beam end, and shear failure in critical areas. When the beam end becomes a weak part, the upper part of the beam end is strained by the reinforcements yield due to the negative bending moment, the lower part of the compressive concrete is crushed and falls off, and the through crack is formed at the beam end. Therefore, when there is an obvious plastic hinge at the end of the beam, the connection is broken by bending.  
Figure 10: Loading apparatus. (**a**) Test setup at the scene. (**b**) Schematic diagram of test setup.  
Figure 9: Test of grouting material. (**a**) Compressive strengths. (**b**) Fluidity.  
In addition, the characteristic of column-end bending failure is the formation of plastic hinges at the column end, and the shear failure in the critical region is manifested as diagonal cracks appearing in the concrete in the critical region.  
Specimen X] exhibited a beam-end bending failure pattern, as shown in Figure 11a. The poor tensile performance of concrete leads to rapid cracking of the tensile zone of the beam under external forces, transferring stress to the steel bars. Therefore, the first vertical crack appeared in the beam's tension area, and then oblique cracks began to appear in the area closer to beam-column interfaces. When loading entered the late stage, macroscopic cracks appeared at the end of the beam. Finally, the beam-column connections' concrete fell off, the reinforcement yielded, and the specimens were severely damaged. The integral RC beam-column connections had significant brittleness characteristics and poor seismic performance. Although the failure pattern of assembled specimens was also beam-end bending, MRPC's tensile strength was higher, and the steel fibers could better inhibit crack occurrence and development; the number and width of cracks were significantly reduced. In addition, there was no concrete spalling off the MRPC surface, as shown in Figure 11.  
The bond between straight steel fibers and the cement matrix was poor; it was easily pulled out, losing the bridging effect and resulting in more comprehensive crack development. Therefore, the SFZP-1 beam had more cracks than the other assembled specimens, as shown in Figure 11a. Compared to straight fibers, the process of drawing end-bent fibers from the MRPC matrix was more complex. Figure 12b,c illustrates that the bending portion at the steel fiber's end was forcibly deformed during the drawing process, providing some mechanical force and thereby enhancing the anchoring force between the steel fiber and the MRPC matrix. Because end-bent long fibers have better anchoring depth, they could effectively suppress the development of macroscopic cracks during the later loading stage and were not quickly pulled out. SFZP-3 had the lowest number of connection cracks; compared to long fibers, SFZP-3 had shorter fibers, and its disorderly distribution system was more compact, which had a significant inhibitory effect on microcracks' generation and development. Figure 12d illustrates wavy steel fibers strengthening the bond with the matrix because of their continuous irregular shapes, which reduced the number of cracks; however, their effect was not as good as that of end-bent steel fibers because the wavy shape could not provide more mechanical bite force to MRPC.  
Figure 11: Failure pattern of X]. (**a**) Critical area cracking. (**b**) Beam end cracking.