  The roughness exponent is reported in numerical simulations with a
three-dimensional elastic beam lattice. Two different types of disorder have
been used to generate the breaking thresholds, i.e., distributions with a tail
towards either strong or weak beams. Beyond the weak disorder regime a
universal exponent of 0.59(1) is obtained. This is within the range 0.4-0.6
reported experimentally for small scale quasi-static fracture, as would be
expected for media with a characteristic length scale.
