Hi Kemo,
It is always a good idea when you want to start a discussion here to tell us what Code you are using and what loadings you want to evaluate. Are you trying to evaluate seismic loadings? .....wind loadings? What is the construction of the bridge? Is the bridge JUST for piping or will there be traffic on the bridge to consider? Please "fill in the blanks".
Thanks, John.
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John Breen