24
1 Static Mechanical Properties of UHPCC
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
0
5
10
15
20
25
30
Deflection (mm)
Load (kN)
0.5%
1.0%
1.5%
2.0%
2.5%
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
0
4
8
12
16
20
24
Deflection (mm)
Load (kN)
0.5%
1.0%
1.5%
2.0%
2.5%
(a)
(b)
Fig. 1.23 Representative three-point flexural load–deflection curves of UHPCC with a microstraight fiber b hooked fiber, Ren et al. (2018), copyright 2020, with permission from Elsevier
One major
crack formation
Fiber-bridging
effect
One major
crack formation
One major
crack formation
Fiber-bridging
effect
(a)
(b)
(c)
Fig. 1.24 Three-point flexural crack pattern of UHPCC specimens with a no mixing fiber b microstraight fiber c hooked fiber, Ren et al. (2018), copyright 2020, with permission from Elsevier
where F un and m 1 are the maximum load and the mass of specimen between the
supports. g is the gravity. α=a c /h and β=L/h are the crack-to-depth ratio and spanto-depth ratio. a c is the critical effective crack length at F un , which can be determined
as follows according to DL/T5332-2005 (2006).
a c =
2
π
(h + h 0 ) arctan
bEV c
32.6F un
− 0.1135
1/2
− h 0
(1.4)
where h0 = 1 mm is the thickness of the steel plate pasted on the specimen, E is the
compressive elastic modulus and V c is the critical value of CMOD at F un .
When β ≥ 2.5, k β (α) can be determined by Guinea et al. (1998)