An Evaluation Method for Effective Prestress of Simply Supported Prestressed Concrete Beams with Breathing Cracks

Table 1

Summary of the investigated system parameters.

Specimen	Strength characteristics of strands	Tension-control stress of strands (MPa)	Average effective tensile stress of strands (MPa)	DM (N·mm)	Load series	Maximum test load, kN
#1	Np0	818.4	786.16	81917919.7	23	90
	1.25Np0	1023	980.67	102186849.3
#2	1.7Np0	1395	1323.79	137939661.7

Single-end tension was used during the test. The load sequences at the middle section are 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 62.5, 57.5, 65, 70, 80, 75, 77.5, 72.5, 82.5, 85, and 90 (unit: kN). The effective prestress calculation method and parameters are taken from the Chinese code “Specifications for design of highway reinforced concrete and prestressed concrete bridges and culverts.”