The central support diaphragm of a trapezoidal steel box girder tested at TRRL was analysed using a linear elastic two-dimensional finite element model. Values of stress and displacement obtained using a range of assumptions on boundary conditions are compared with values obtained experimentally. Interaction between the diaphragm and the lower flange was considered to have contributed to an increase in the effective area of the flange acting with the diaphragm. Increasing the area in the model and allowing for an alternative load path around the diaphragm through the lower flange and stiffeners gave stress distributions similar to those obtained experimentally.

Want to know more about this project?