Abstract：To acquire the stress-strain relationship curve of Ultra-High Performance Concrete (UHPC) easily, a point-by-point Twice Inverse Analysis Method (TIAM) considering the influence of shear deformation and the nonlinear distribution of curvature is proposed. Based on the four-point bending tests, the load-deflection curves of specimens casted by different methods are converted into tensile stress-strain curves by TIAM. Following aspects are demonstrated. Firstly, the shear-moment deflection ratio of a beam (both the shear-span and depth-span ratio 1/3), sums up to 24.8%, indicating that it is unreasonable to neglect shear deformation. Secondly, the tensile stress-strain curves obtained by TIAM exhibit pseudo strain-hardening behaviors and the points of the load-deflection curves at the limit of proportionality correspond approximately to those of direct tension tests at linearity deviations. Thirdly, the stress levels of tensile stress-strain relationship derived by TIAM are slightly higher than those from tensile tests, while the stress of the specimens casted horizontally is 10% larger than that of specimens casted vertically. Lastly, with the direct tensile results as reference, strain characteristics of the stress-strain curves by TIAM show an outperformance than those by other point-by-point inverse analysis methods. Therefore, TIAM is feasible to determine the stress-strain relationship of UHPC.
