jochav52802
Structural
- Nov 28, 2018
- 80
Hello All,
I'm designing a hanging rectangular frame to support some elevated IMP walls off of an existing manufacturing building. The frame will be composed of channel beams supported vertically by wire-ropes; the wire rope supplier indicated that the ropes should utilize a safety factor of 10 since they are supporting a permanent overhead load, (by comparison, they specify that a safety factor of 5 should be used for temporary rigging applications.)
Additionally, the lateral restraints for the frame will utilize Square HSS sections since they need to resist both tension/compression, (this is because we can only place lateral restraints on one side of the frame in both the North/South & East/West directions due to the building geometry restrictions.) The end-connections for the lateral restraints will be composed of a male/female pinned connection.
With that said, I'd appreciate help with the following questions:
1) 10 seems like a ridiculously over-conservative safety factor to use; by comparison, the AISC 360-16 steel code only requires an ASD safety factor of 1.5/2.0 for tensile yielding/rupture limit states. Is it common practice to use a safety factor of 10 for wire ropes supporting permanent structural assemblies?
2) Since the ropes are designed for a safety factor of 10, should all of the subsequent supporting connections and members also be designed for the same safety factor of 10 regardless of what the steel code requires? It would seem strange to not design all of the supporting elements for the same safety factor, otherwise they would fail long before the ropes ever reached their capacity.
3) What would be an appropriate/standard practice type standard/procedure to follow for designing the pin diameters for the pinned end-connections for the lateral restraints? Would something within the CMAA group be appropriate?
Many thanks for your time/help!
I'm designing a hanging rectangular frame to support some elevated IMP walls off of an existing manufacturing building. The frame will be composed of channel beams supported vertically by wire-ropes; the wire rope supplier indicated that the ropes should utilize a safety factor of 10 since they are supporting a permanent overhead load, (by comparison, they specify that a safety factor of 5 should be used for temporary rigging applications.)
Additionally, the lateral restraints for the frame will utilize Square HSS sections since they need to resist both tension/compression, (this is because we can only place lateral restraints on one side of the frame in both the North/South & East/West directions due to the building geometry restrictions.) The end-connections for the lateral restraints will be composed of a male/female pinned connection.
With that said, I'd appreciate help with the following questions:
1) 10 seems like a ridiculously over-conservative safety factor to use; by comparison, the AISC 360-16 steel code only requires an ASD safety factor of 1.5/2.0 for tensile yielding/rupture limit states. Is it common practice to use a safety factor of 10 for wire ropes supporting permanent structural assemblies?
2) Since the ropes are designed for a safety factor of 10, should all of the subsequent supporting connections and members also be designed for the same safety factor of 10 regardless of what the steel code requires? It would seem strange to not design all of the supporting elements for the same safety factor, otherwise they would fail long before the ropes ever reached their capacity.
3) What would be an appropriate/standard practice type standard/procedure to follow for designing the pin diameters for the pinned end-connections for the lateral restraints? Would something within the CMAA group be appropriate?
Many thanks for your time/help!
