Method for measuring crack width and normal section bearing capacity of unreinforced steel fiber concrete duct piece

The invention discloses a method for measuring crack width and normal section bearing capacity of an unreinforced steel fiber reinforced concrete shield segment, which comprises the following steps of: S1, obtaining test loading force F-W curves of unreinforced steel fiber reinforced concrete with different mixing amounts under different opening displacements through an unreinforced steel fiber reinforced concrete opening beam three-point bending test; s2, obtaining a flexural-tensile strength-opening displacement relation under the condition of different steel mixing amounts; s3, establishing an elastic flexural-tensile residual strength ratio-steel mixing amount relationship; s4, judging a rigid-plastic constitutive model or a post-crack soft/hardened constitutive model; s5, obtaining a tensile residual strength design value fFtu; s6, obtaining the steel fiber stress increment after the unreinforced steel fiber concrete is cracked; s7, obtaining the stress increment of the steel fibers transmitted to the co