Integrated Buildings & Structures

------Original Message------

Hi

I'm designing new connections in a seismic retrofit project for some struts of a warehouse with wooden trusses as the primary load bearing system. I change the strut members whereever needed by checking their forces against the compression capacity. As you know, if I want to design them against the compression capacity the member sizes is larger than if I want to design them for just tension since my unbranded length is high. 
The question is which force should I use to design the connection?
1- Compression capacity 
2- Tensile capacity 
3- The force I get from the analysis.

P.S The analysis procedure is dynamic analysis so I have the same forces both for tensile and compression in my analysis. So I should assume we have the maximum axial load for tensile and compression. It means when I was designing the members I didn't care if that force is compression or tensile in the strut. I took the maximum load in the analysis and assumed it is a compression and design the member to tolerate that force and doesn't  buckle against it. 


Thanks,

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Arash S.M.ASCE
Memphis TN
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​

------Original Message------

The above stated statement will vary as per design being considered with respect to the load acting according to standard codes.

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Adlin Antony C.Eng, S.M.ASCE
Trivandrum
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Original Message:
Sent: 01-31-2018 08:54
From: Hengfeng Wang
Subject: Connection Design Force

Normally, the compression and tension are different even through the dynamic analysis is used for some load cases. For example, the dead loads are always there. Both tension and compression shall be checked.

 

HENGFENG WNAG, Ph.D

Structural Engineer

HOK

5 Bryant Park

1065 Avenue of the Americas  |  New York NY 10018 USA

t +1 646 385 7600  megan.tuite@...

 

Original Message------

The design force will depend on the behavior of strut. From analysis, extract the value of stress whether compression or tension. Design for that force. Generally, I think the wood strut is provided to resist compression as tension capacity is low. So I believe member should be designed according to analysis for compression and check in tension.

In my opinion, you need to design the members and all connection for all of the possible failure modes. If the connection can be subject to both tension and compression loads, then you need to design for both.

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Andrew Holmes P.E., L.S., M.ASCE
Consulting Engineer
Melbourne FL
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Original Message:
Sent: 01-30-2018 01:29
From: Abhiraj Rathod
Subject: Connection Design Force

The design force will depend on the behavior of strut. From analysis, extract the value of stress whether compression or tension. Design for that force. Generally, I think the wood strut is provided to resist compression as tension capacity is low. So I believe member should be designed according to analysis for compression and check in tension.

Original Message------

Hi

I'm designing new connections in a seismic retrofit project for some struts of a warehouse with wooden trusses as the primary load bearing system. I change the strut members whereever needed by checking their forces against the compression capacity. As you know, if I want to design them against the compression capacity the member sizes is larger than if I want to design them for just tension since my unbranded length is high.
The question is which force should I use to design the connection?
1- Compression capacity
2- Tensile capacity
3- The force I get from the analysis.

P.S The analysis procedure is dynamic analysis so I have the same forces both for tensile and compression in my analysis. So I should assume we have the maximum axial load for tensile and compression. It means when I was designing the members I didn't care if that force is compression or tensile in the strut. I took the maximum load in the analysis and assumed it is a compression and design the member to tolerate that force and doesn't  buckle against it.


Thanks,

------------------------------
Arash S.M.ASCE
Memphis TN
------------------------------
​

The axial forces at connections are transmitted in the form of end bearing, shear, and bending.
The maximum tensile force should be taken to determine the rupture strength or weaker rupture plane.
The maximum axial force (either tension or compression) should be considered for determining the sizes required for shear, bearing and bending (such as the thickness of plates and bolt diameters).

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Dr. Muhammad Umair Saleem
C.Eng, M.ASCE, P.Eng
Assistant Professor
King Faisal University
Hofuf Alahsa
------------------------------

Original Message:
Sent: 01-30-2018 01:29
From: Abhiraj Rathod
Subject: Connection Design Force

The design force will depend on the behavior of strut. From analysis, extract the value of stress whether compression or tension. Design for that force. Generally, I think the wood strut is provided to resist compression as tension capacity is low. So I believe member should be designed according to analysis for compression and check in tension.

Original Message------

Hi

I'm designing new connections in a seismic retrofit project for some struts of a warehouse with wooden trusses as the primary load bearing system. I change the strut members whereever needed by checking their forces against the compression capacity. As you know, if I want to design them against the compression capacity the member sizes is larger than if I want to design them for just tension since my unbranded length is high.
The question is which force should I use to design the connection?
1- Compression capacity
2- Tensile capacity
3- The force I get from the analysis.

P.S The analysis procedure is dynamic analysis so I have the same forces both for tensile and compression in my analysis. So I should assume we have the maximum axial load for tensile and compression. It means when I was designing the members I didn't care if that force is compression or tensile in the strut. I took the maximum load in the analysis and assumed it is a compression and design the member to tolerate that force and doesn't  buckle against it.


Thanks,

------------------------------
Arash S.M.ASCE
Memphis TN
------------------------------
​

If the forces are equal, I think you would want to design the connection in tension since the end distance requirements for a fastener loaded toward the member end needs to be larger for full design strength.  See 2018 NDS Table 12.5.1A (http://awc.org/pdf/codes-standards/publications/nds/AWC-NDS2018-ViewOnly-171117.pdf

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).

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Bradford Douglas P.E., M.ASCE
AWC Vice President, Engineering
Leesburg VA
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