Navigation:  Step-By-Step Examples > Example 16: Design of Steel Beam

Problem Description

Select the lightest W section for the simply supported beam of L = 50ft, Lb = 25 ft.  The superimposed load is 0.4 kip/ft dead load and 1.0 kip/ft live load.  Use A992 steel.

[Ref 22, pp 435-437].  

 

Suggested Modeling Steps

▪Set proper units from Settings and Tools > Units & Precisions.  

 

 

▪Define load cases from Create > Load Cases

 

 

▪Define the load combination from Create > Load Combinations: make sure “Perform Steel Design using this Load Combination” is checked.

 

 

▪Define the material from Modify > Member Properties > Materials using the standard steel Steel-A992--Fy50.  Steel properties such as Fy and Fu are set automatically.

 

 

▪Define the section W18x97 from Modify > Member Properties > Sections using the AISC table.  

 

 

▪Define the two nodes from Tables > Nodes.  

 

 

▪Define the one beam from Tables > Members

 

 

▪Define the two supports from Tables > Supports

 

 

▪Define both the dead and live line loads from Tables > Line Loads

 

 

▪Define the self weight from Tables > Self Weights.  Make sure the self weight acts in the negative global Y direction.

 

 

▪Set structural model as 2D Frame from Analysis > Analysis Options.  Run Static Analysis to make static analysis results available for steel design.

 

 

▪Define the steel member design criteria from Steel Design > Steel Design Criteria > Steel Member Design Criteria.  Use “W” as the section prefix as we want to find the light W section.  We could also use “W12, W18” for the section prefix if we would want to use either W12 or W18x sections.  Make sure Cb = 0 so we will have the program calculate it automatically. Important: If 0 is entered for Lb for non-continuously braced, then Lb is taken as the member length.  If the member is fully braced laterally, you must enter 0 for Lb.

 

 

▪Define the steel member input from Steel Design > Steel Member Input.  

 

 

▪Perform the steel design from Steel Design > Perform Steel Design.  

 

▪View the steel design results from Steel Design > Steel Design Results.  By default, up to 10 candidate sections are available.  The W18x97 happens to be the lightest section.  Also notice that Cb is calculated automatically (Cb = 1.3).  If desired, we could now update the member with a different section candidate, reanalyze the model and perform the steel design again.  

 

You can also view the detailed step-by-step calculation procedures for the most critical load condition on each member.