This paper presents a numerical simulation of quasi-brittle fracture in UHPFRC I-beam as a linear complementarity problem. Based on the investigation of Tin-Loi and Attard, the simulation of quasi-brittle fracture in concrete has been extended to model UHPFRC I-beam by including a tensile hardening. Fracture is simulated through a hardening-softening fracture constitutive law in tension and a softening fracture constitutive law in shear at the boundary nodes, with the material within the triangular unit remaining linear elastic. LCP is used to formulate the path-dependent hardening-softening behavior in non-holonomic rate form. The good matching of test results and numerical results indicates the effectivity of this method.