Papers by Keyword: Unbonded Prestressing

Abstract: This papers deals with the study of the influence of prestress force on the natural frequencies for unbonded prestressed concrete beams. A total of 5 unbounded prestressed concrete simply support beams were constructed and tested. The test results show that the prestress force has little effect on the nature frequencies of unbonded prestressed concrete beams. A model of variable stiffness is proposed to calculate the natural frequencies of prestressed concrete beams with unbonded tendons, which assumed that the flexural rigidity of the beam is changing when beams vibrating. The calculate results show that the calculation results by the proposed model agree well with experimental ones.

Abstract: Reactive Powder Concrete (RPC) has excellent properties such as high toughness and high durability. In this paper, based on the experimental research of the different unbonded prestressed tendons of the unbonded partially prestressed RPC beams, the crack calculation of prestressed RPC beams is analyzed. The results show that the crack regulation is special in some extent of the unbonded partially prestressed RPC beams. It is suggested that the crack width of unbonded partially prestressed RPC beams calculated in accordance with the specification for unbounded partially prestressed concrete structure should multiply the reduction factor of 0.7.

Abstract: An experimental investigation on the dynamic characteristics of unbounded prestressed concrete simply support beams is presented in this study. A total of 3 unbounded prestressed concrete simply support beams were constructed and tested. The main variables considered in the test study were the prestress level, the position of prestressed steel and concrete damage. The test results shows that the natural frequencies and model shape of prestressed concrete beams change with the prestress level and the position of prestressed steel, and that the existence or not of concrete crack have certain effects on the dynamic characteristics of prestressed concrete beams.