Large-scale testing and numerical study on an innovative dovetail UHPC joint subjected to negative moment

Qifeng Zhang, Yan Feng, Zhao Cheng, Yang Jiao, Hang Cheng, Jingquan Wang and Jianan Qi

Abstract

To study the working mechanism and size effect of an innovative dovetail UHPC joint originated from the 5th Nanjing Yangtze River Bridge, a large-scale testing subject to negative bending moment was conducted and compared with the previous scaled specimens. The static responses, i.e., the crack pattern, failure mode, ductility and stiffness degradation were analyzed. It was found that the scaled specimens presented similar working stages and working mechanism with the large-scale ones. However, the post-cracking ductility and relative stiffness degradation all decrease with the enlarged length/scale, apart from the relative stiffness after flexural cracking. The slab stiffness at the flexural cracking stage is 90% of the initial stiffness while only 24% of the initial stiffness reserved in the ultimate stage. Finite element model (FEM) was established and compared with the experiments to verify its effectiveness in exploring the working mechanism of the innovative joint. Based on this effective method, a series of FEMs were established to further study the influence of material strength, pre-stressing level and ratio of reinforcement on its deflection-load relationship. It is found that the ratio of reinforcement can significantly improve its load-carrying capacity among the three major-influenced factors.

Key Words

joint; large-scale testing; negative bending moment; numerical simulation; ultra-high-performance concrete (UHPC)

Address

Qifeng Zhang, Yan Feng: Key Laboratory of Concrete and Prestressed Concrete Structures of Ministry of Education, School of Civil Engineering, Southeast University, Nanjing 211189, China Zhao Cheng: Key Laboratory of Concrete and Prestressed Concrete Structures of Ministry of Education, School of Civil Engineering, Southeast University, Nanjing 211189, China; Bridge Engineering Research Center of Southeast University, Southeast University, Nanjing 211189, China Yang Jiao, Hang Cheng: Key Laboratory of Concrete and Prestressed Concrete Structures of Ministry of Education, School of Civil Engineering, Southeast University, Nanjing 211189, China Jingquan Wang, Jianan Qi: Key Laboratory of Concrete and Prestressed Concrete Structures of Ministry of Education, School of Civil Engineering, Southeast University, Nanjing 211189, China; Bridge Engineering Research Center of Southeast University, Southeast University, Nanjing 211189, China; National Prestress Engineering Research Center, Southeast University, Nanjing 211189, China

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