The finite-element analyses are done by assuming higher values of tensile strength of the brick masonry and the filler material in such a way that no cracks are developed from increasing axle loads. The analysis is carried by increasing the axle loads on the BOXNEL . Fig. 6 shows the plot of maximum principal stress at the crown of Span 1 with respect to the applied axle load. From this figure, it is seen that the rise in the maximum principal stress is only about 0.1 MPa for an increase of a 980-kN (100-t) axle load, which is quite small. Furthermore, at a 245-kN (25-t) axle load and without the self-weight, the maximum principal stress near the crown is 0.0245 MPa (0.16 MPa with self-weight). Because no cracks were visually observed at this load in the field studies, it is expected that the minimum tensile strength of the masonry arch is more than 0.16 MPa.
Read More: http://ascelibrary.org/doi/full/10.1061/%28ASCE%29BE.1943-5592.0000338