METHODOLOGY FOR AUTOMATION OF CONTINUOUS HIGHWAY BRIDGE DESIGN

A methodology is described for cost optimal design of continuous multispan highway bridges in a complete automated mode, i.e. without user interaction. The methodoloy involves the integration of the following: stress analysis; deisgn force computation; and optimization. The structure can be analyzed by finite-element methods. Design force computation in bridge design invovles the use of inlfluence lines or influence surfaces. To compute influence coefficients in the automated design process, the 'adjoint method' is used. The development of a capability to compute design forces from inlfuence surfaces is described. The methodology described in the paper is used to develop the SPGBROD program which cost optimizes straight, continuous, multispan, steel plate girder highway bridges. An example is discussed to indicate the advantages of the suggestd methodology as compared to the conventional design approach.