Truss Beam For An Industrial Building

    It has been proposed that a standard, equal leg structural steel angle be used for this application using ASTM A36 structural steel. Using the AISC (American Institute of Steel Construction) code, specify a suitable angle from Appendix A-5 shown. Following steps may be useful in fulfilling this task. Step1. Determine the yield strength sy and the ultimate strength su of the A36 steel either from your Materials Science class book/notes, the course textbook, or by researching over the internet. Step 2. Calculate the design stress σd that CAN NOT be exceeded in all or part of the structure. According to AISC code, for direct normal stresses due to static loads on steel members of building-like structures, or whichever is lower. Step3. Calculate the area A of the A36 steel truss member by , where Fmax is the highest load in the truss members, calculated in part 2 point d. Step 4.      

Sample Solution

   

Step 1: Determine the yield strength sy and the ultimate strength su of the A36 steel

The yield strength sy of A36 steel is 36 ksi (248 MPa) and the ultimate strength su is 58 ksi (400 MPa).

Step 2: Calculate the design stress σd that CAN NOT be exceeded in all or part of the structure

According to the AISC code, for direct normal stresses due to static loads on steel members of building-like structures,

Full Answer Section

     
σd = 0.6 * sy

or

σd = 0.5 * su

whichever is lower.

Therefore, the design stress σd for A36 steel is:

σd = 0.5 * 58 ksi = 29 ksi

Step 3: Calculate the area A of the A36 steel truss member

The area A of the A36 steel truss member can be calculated using the following equation:

A = Fmax / σd

where Fmax is the highest load in the truss members.

For example, if the highest load in the truss members is 10 kips, then the area A of the A36 steel truss member would be:

A = 10 kips / 29 ksi = 0.345 in²

Selecting a suitable angle from Appendix A-5

To select a suitable angle from Appendix A-5, we need to find an angle with an area greater than or equal to 0.345 in².

The smallest angle from Appendix A-5 with an area greater than or equal to 0.345 in² is the L4x4x3/8 angle. This angle has an area of 0.386 in².

Therefore, a suitable angle from Appendix A-5 for this application is the L4x4x3/8 angle.

Conclusion

The suitable angle from Appendix A-5 for this application is the L4x4x3/8 angle. This angle has an area greater than or equal to the required area of 0.345 in² and is made of ASTM A36 structural steel.

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