*Article* **Experimental Investigation on Bending Behavior of Existing RC Beam Retrofitted with SMA-ECC Composites Materials**

**Hui Qian , Qingyuan Zhang, Xun Zhang \*, Enfeng Deng and Jundong Gao**

School of Civil Engineering, Zhengzhou University, Zhengzhou 450001, China; qianhui@zzu.edu.cn (H.Q.); dayuanzi815@126.com (Q.Z.); dengenfeng@zzu.edu.cn (E.D.); gaojundong@zzu.edu.cn (J.G.)

**\*** Correspondence: zhangxun@zzu.edu.cn

**Abstract:** In order to realize the self-centering, high energy consumption, and high ductility of the existing building structure through strengthening and retrofit of structure, a method of reinforced concrete (RC) beam strengthened by using Shape Memory Alloy (SMA) and Engineered Cementitious Composites (ECC) was proposed. Four kinds of specimens were designed, including one beam strengthened with enlarging section area of steel reinforced concrete, one beam strengthened with enlarging section area of SMA reinforced concrete, beam strengthened with enlarging section area of SMA reinforced ECC, and beam strengthened with enlarging section area of steel reinforced ECC; these specimens were manufactured for the monotonic cycle loading tests study on its bending behavior. The influence on the bearing capacity, energy dissipation performance, and self-recovery capacity for each test specimens with different strengthening materials were investigated, especially the bending behavior of the beams strengthened by SMA reinforced ECC. The results show that, compared with the ordinary reinforced concrete beams, strengthening existing RC beam with enlarging section area of SMA reinforced ECC can improve the self-recovery capacity, ductility, and deformability of the specimens. Finally, a revised design formula for the bending capacity of RC beams, strengthened with enlarging sections of ECC, was proposed by considering the tensile capacity provided by ECC, and the calculated values are in good agreement with the experimental value, indicating that the revised formula can be well applied to the beam strengthening with enlarging section of SMA-ECC Materials.

**Keywords:** shape memory alloys; engineered cementitious composites; composites materials; selfrecovery capacity; bending behavior
