One way is to fine divide the elements, so that both the values match. In the Loss table only at I & J end is provided, where as in tendon stress check, stresses are arrived at all the five points for each element and tabulated and hence accordingly the variation between both the tables. If the maximum stress point does not fall within the 5 points ( i, 1/4,1/2,3/4,j ) of the elements, you can note the difference between the values in Loss table and stress table. This is mainly attributed to the, points in which midas gives output results. You may note that these stresses do not exactly match. Point 1 refers to FDL1 i.e the stress at tendons at anchorage Point 2, is little tricky. I have attached a model file, in which I would refer how these values are derived for tendon stress check. Answer1 : If you may refer the help menu, following is stated. I was hoping you could point me in the direction of someone who has some expertise here who could help clear this up for me. Specifically, because the program doesn’t show how it has calculated the losses in the prestressing strands explicitly I am having trouble determining exactly how the program is coming up with the stress in the tendons (FDL1, FLL1). In this case geometric non linear analysis has to be carried and an elastic catenary behaviour of the cable is considered.Question1 : I have a some questions I would like to ask. More detailed analysis may require cable elements be m odelled. The model is checked if the stiffness of the truss is sufficient to resist the initial Dead load. Usage in Cable Bridges For preliminary design of the cable bridges we go for modelling of cables as equivalent truss elements. suspension and cable-stayed bridges, where in large deformation effects can not be neglected. It’s effective in case of cable bridges i.e. General Usage Used for both cable bridges as well as for modelling struts and ties of general bridges. Non linear behaviour, no superimposition When non linear behaviour of cable is considered, superimposition of load cases are ruled out and combined effect of loads has to be considered. Load Combinations Superimposition possible Linear combinations of load cases can be made to compare truss force results. Hence consideration of sag becomes important. Sag is predominant Cable elements are inherently non linear and the stiffness changes with the load applied.
Main differences in these elements are as tabulated below: Feature Truss Element Cable Element Sag Effect No Sag Truss element, is linear in general and has constant stiffness. Truss element can resist both tension and compression, while a cable element can resist only tension.
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