Experimental Study on Fatigue Performance of Negative Bending Moment of Steel-Concrete Continuous Composite Box Girder

Table 2

Basic mechanical properties of concrete at 7 days and 28 days.

Age/day	Test type	Specimen number	Measured value (MPa)	Use value (MPa)
7	Compressive strength	1	46.23	46.93
		2	49.38
		3	45.19
	Tensile strength	1	2.76	3.08
		2	3.01
		3	3.47
	Elastic modulus	1	32800	35300
		2	38900
		3	34100
28	Compressive strength	1	52.26	56.42
		2	56.1
		3	60.89
	Tensile strength	1	3.52	3.68
		2	3.83
		3	3.7
	Elastic modulus	1	36500	40500
		2	43900
		3	41100