Experimental study on assembled monolithic steel-prestressed concrete composite beam in negative moment.

In recent years, the application of steel-concrete composite beam has gained popularity due to its mechanical property, economical and construction efficiency. However, in the negative moment areas, tension occurs in the concrete deck, which is undesirable and needs to be carefully addressed. As a result, prestressing tendons were used in the precast concrete deck by pretensioning, which can effectively solve the cracking problem of concrete deck in negative moment of a continuous composite beam and avoid steel beams consuming partial prestress. This paper presents 8 experiments which were designed to verify the mechanical property of assembled monolithic steel-prestressed concrete composite beams (AMS-PCCB) in negative moment. Shear stud groups (SSGs) or steel block shear connectors (SBSCs) were used in the AMS-PCCB. The effects of shear connector, prestressing, deck width, and deck processing technique on the flexural capacity, interface slip, and crack development of the composite beam in negative moment were investigated. The test results show that the prestressing tendons improve the cracking load significantly, while it has no obvious influence on the flexural capacity. So, the flexural capacity of the composite beam in negative moment can be calculated using the plastic analysis method without the consideration of prestressing tendon. Based on the test results and available calculation methods, modified methods for determining the crack spacing and width in a negative moment region were proposed. • The mechanical property of AMS-PCCB in negative moment were investigated. • The prestressing was found to improve the cracking load significantly. • The efficiency of prestressing can be improved by pretensioning in PC deck. • The effect of prestressing can be ignored to calculate ultimate flexural capacity. • The modified formulae were proposed to calculate the crack spacing and width. [ABSTRACT FROM AUTHOR]