×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Factors of safety for shoring design.

Factors of safety for shoring design.

Factors of safety for shoring design.

(OP)
Consider shoring design basics as an example.

Passive pressure is a resisting force to which we apply a factor of safety to obtain a lower allowable passive pressure for design.

The active pressure is a driving force. Is a factor of safety applied to the active load to obtain a higher active pressure value for design?

RE: Factors of safety for shoring design.

Usually, margins are only applied once. The load is assumed higher (like in rigging designs), or the load is left based on the original contract specifications and assumptions; and the "ability to resist loads) is reduced. If the contract requires a floor to carry a 42,000 truck, the owner has said he needs that capacity. You don't design for a 84,000 truck.

However, ...

For example, the steel in that platform will be assumed to be 36,000 yield, but the actual metal purchased to A36 specification may be 36 ksi to 44 ksi. A safety factor might be 1.25 or 1.5 or 2.0, so the assigned yield of 36,000 is reduced to a design maximum stress of 18,000 psi using that alloy at that location. Is the platform "over-designed sicne the metal might carry two times the 42,000 lb truck? No.

wire rope is specified to break at 120,000 lbs load, but might be limited to 1/4 that amount (30,000 lbs) when the rigging plan is worked.

You don't "increase the assumed load" arbitrarily unless a dynamic or impact scenario is being worked. Then, you make the appropriate assumptions and acceleration changes to find the design load.

Once you have a design load, work from there.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources