Abstract:The deformation and failure mechanism of voussoir beam were analyzed with physical modeling. Three sets of curves of deflection versus axial load,transverse load,coefficient of movement arm for voussoir beam were obtained. These curves consist of two parts,i.e. before and post-peak curves,which show the progressive failure of voussoir beam. Test results show when the initial axial load is low;and the deflection curve versus coefficient of movement arm reaches to the peak value at first. Then the curves of transverse load and the axial thrust follow,which means that the coefficient of movement arm is the most critical to the failure of voussoir beam. However,when the initial axial load is high,the above-mentioned three kinds of curves reach to the peak values at the same time. The achieved results show that the values of axial load and the ratio of span to thickness directly affect the behavior of voussoir beam.