CSI Bridge result output 1

[tmalik3156]

Good day.
My question is for those who are familiar with CSI Bridge software, and its moving load analysis output.
As shown attached, this is the tabulated output that CSI generates.
Take Frame 12 for example. This is a compression member, so I need to combine Thrust (P) and Moment (M3) to check if the member is satisfactory against buckling etc.
Rows are sorted by Max and Min for a particular station.
As can be seen, P = 2557 and M3 = 2618 are in the same row for station 0. The larger P (4550) is located further down but the corresponding M3 is low.
But are all the values in a particular row concurrent? That is, do we know that P = 2557 and M = 2618 occur at the same time? If not, what P and M3 values should I combine?

 

[centondollar]

You have posted results of load combinations. Presumably, one row corresponds to one combination ("CaseType", "OutputCase"), but you are the engineer doing calculations, so it's up to you to verify what the tabulated results mean.

Is this a truss or pile? Why are there both axial forces and bending moments? Did you run a second-order (p-delta or actual second-order with von Karman strains) analysis?

The worst-case loading condition is found by dimensioning the structure at critical cross-sections based on the sectional forces. If you systematically input each row (load combination result) and do the design, you will eventually find the case with largest utilization ratio, i.e., the worst-case situation.

 

[tmalik3156]

@ centondollar, It's an arch bridge rib. It's predominantly under compression, but with some accompanying moments.

 

[WJA]

No, P = 2557 and M = 2618 do not necessarily coexist. This is an envelope case, and the "max" line is showing the maximum value for each force direction. To be conservative, you should consider the largest moment together with the range of axial forces (i.e. 2557 or 4550). Create additional cases to get a more precise result, or define the cases as "corresponding" (there's a check-box for this) to get the corresponding forces under a live load case.

 

[tmalik3156]

Thank you very much WJA. That was most helpful.