###### Abstract  
Cracking is one of the main diseases of small- and medium-span reinforced concrete (RC) bridges. It is a key problem to determine the change in mechanical properties of RC beams after cracking in bridge-performance evaluation. The present study performs static loading tests on seven simply supported T-beams with different crack damage conditions. The influences of crack location, crack depth and steel-bar diameter at a prefabricated crack on the stress, deflection and crack distribution pattern of pre-cracked test beams are investigated. The failure mode and mechanism of pre-cracked beams are revealed. Based on the experimental results, a finite element model of a pre-cracked beam is developed and validated. Following this, a theoretical prediction method is proposed to calculate the ultimate load of pre-cracked RC beams. The results indicate that the direct damage to mid-span section size can significantly affect the stiffness of the RC beam. The local damage of the tensile steel section has insignificant influence on the overall stiffness of the beam. The stiffness degradation of the pre-cracked beam at the quarter span is smaller than that of the pre-cracked beam at mid-span. The strain of the T-beam section in the pre-cracked test conformed to the assumption of the flat section. The experimental observations are in good agreement with the theoretical predictions, which can provide a theoretical basis for the performance evaluation of existing RC beams. b +  
and structural capacity of an RC member [22; 23; 24]. Based on experimental investigations, the dynamic response of the RC beam to the development of cracks was investigated [25], and the stress-strain curves of tensile concrete in cracked RC beams were also presented [26]. Other researchers established a comprehensive model to accurately describe the whole process of crack initiation, propagation and rotation [27]. [PERSON] et al. [28] used image recognition processing and machine learning regression technology to establish the relationship between the surface-crack-distribution information and the bearing capacity of RC beams. However, most of the existing studies focused on the cracking location of a complete beam under test or environmental load. The obtained variation law or model cannot be directly applied to the bridges with cracks before formal operation [29], and it is necessary to improve and supplement the relevant results. Finite element (FE) numerical simulation has the advantages of convenient parameter adjustment and reasonable characterization of data results [30; 31; 32; 33], which has become an indispensable tool in the field of concrete structures. [PERSON] et al. [34] determined the flexural stiffness of simply supported RC beams with prefabricated cracks using the FE model modification method. [PERSON] et al. [35] established an FE model that can reveal the influence of cracks on the section stiffness of RC members under short-term loads. [PERSON] et al. [36] further clarified the influence of initial cracks on the bearing capacity of cracked beams by FE simulation. In addition, [PERSON] et al. [37] investigated the influence of initial crack location, width, depth and longitudinal-reinforcement ratio on the dynamic performance of pre-cracked RC beams, using the numerical method. The results showed that the dynamic behavior of pre-cracked RC beams was insensitive to the width and depth of initial cracks, to a certain extent. However, the existing works mainly focused on the stiffness degradation or flexural behavior of the beam under crack development, and the analysis data mainly come from numerical simulation. FE numerical simulation has the disadvantage of the idealistic application or assigning process of materials, boundaries and loads, which may deviate from the real test results. The credibility of a single FE simulation is questionable. The FE model must be modified and verified, based on the test results.