Verification Moment and Shear Diagram of Design Beam and Structure, Transferred to Beam data Load Case.

[kidsnextdoor1809]

Hello, Everyone, I'm trying to study SBD, so I'm a newbie of this one and a university students, currently, I'm trying to understand the flow of this software by doing this example. In this example, I try to design a 5m length simply supported beam like this one with the concentrated load P=10kN at the middle of the beam, concentrated moment =40kN, linear distributed load from 2,5m to 3.5m, dead load = 2kN/m, live load =4kN/m.

I have completed the Defining material, Design Beam, Structural Definition, Structural Properties, Loads and Compilation. My Results for Moment Diagram show in the results which is also make senses. Now I’m to trying to transfer the results manually (not automated loading) into Design beam to perform the concrete reinforcement calculation. By doing Calculate/ Transfer Results. I don’t really understand the Design Load cases, so I Choose "Transient Load BM 1" for both strength and Service limit stated (I don’t know if my selection makes sense or not) and the results I Get for design beam is like this one. I have 2 questions

• Why the force/moment diagram in the structure results with compilation forces is different from the moment/force diagram is the design beam, what is the meaning of moment/force diagram in the design beam.

• Since this example is just a basic general example, how can I choose the load case for beam transfers manually. I think my beam load does not belongs to any types in these following, I also want to create a defaults beam loads, is there anyway to do it? 
• 

Thank you for your helps. I also want to post my project files. 

[dave_geeves]

Hi,

Thanks for attaching your data file.  I am currently working on this and will get back to you as soon as possible.

Kind regards

Dave Geeves

[dave_geeves · Accepted solution]

Hi,

To answer your first question regarding the difference in the moment and shear diagrams between the analysis results and the beam loading effect tables it is necessary to understand the way in which the program transfers the results.

• for moment effects, the program looks at each point along the beam and averages the moment in the beams either side of the joint - as such, the moment discontinuity arising from the point moment applied load is not represented. In reality for bridges, an applied moment at a point within the span of a beam is not very common so this is not generally an issue, in fact moment diagrams are nearly always continuous functions along the span

• For shear effects, where discontinuities over a short length are realistic, the program transfers the maximum absolute value of shear arising from the beams attached to a joint.  Therefore all shear values are positive.

What this means is that the maximum moment in your case will not be designed for but the maximum shear would.  If this was causing a problem in reality then an additional load point cold be added into the loading table, 10mm away from the discontinuity and the max/min moment values at the discontinuity could be added by hand.

With regard to the selection of a suitable load table, what you have done is perfectly valid for an overall flexural moment design at Strength and Service limit states but you will need to enter two more lines into the transfer table for transient Load Shear force design (Strength and Service) using the same Strength and Service combinations.

For a more general approach it is common practice to create combinations for permanent self-weight loads, superimposed dead loads, and transient loads separately.  These can then be entered separately into the transfer table as "construction Loads" , "SDL loads" and various "Transient Loads".  This then allows the design of construction, as built and transient load situations.  The values from the appropriate tables are added together to form the total design effect for the design situation selected.

I hope this has been helpful and if this has answered your query then pleas mark my reply as a solution so that others may benefit.  Thanks

Kind regards

Dave Geeves

[kidsnextdoor1809]

Thank you very much, your answer helps me alot, i'm very appreciate