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

Table 3

Material calculation parameters.

Material name	Density (T/mm^3)	Modulus of elasticity (MPa)	Poisson’s ratio	Average effective tensile stress of strands (MPa)	Assumed maximum principal stress (MPa)	Assumed fracture energy (N/mm)
C50 concrete	2.6 × 10^−9	3.45 × 10^4	0.2		0.01	0.01
Steel	7.85 × 10^−9	2.0 × 10^5	0.3		—	—
Strand	7.85 × 10^−9	1.95 × 10^5	0.3	Np0: 786.16 MPa
				1.25Np0: 980.67 MPa	—	—
				1.7Np0: 1323.79 MPa

The load series at the middle section is 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); and the computing moment ΔM_L/2 = ΔP × L_j/4 (unit: N·mm). Average effective tensile stress of strand reference from Table 1.