JAE
Structural
- Jun 27, 2000
- 15,669
The IBC has requirements in Chapter 17 on structural load tests which apply to structures where the capacity is unknown and difficult or impossible to verify by calculations.
In those sections they typically require a load to be applied to a structure in excess of the design load. The IBC, in section 1713, requires a load of 2 times the design load to be used.
This then is essentially a safety factor of 2.0.
In the ASME BTH-1 document, for say a hanging assembly to lift materials up to a higher level during construction, the BTH requirements for design use higher safety factors
than typical...say 3.0.
The question: If you are trying to verify the safety of an assembly that is already built, and you perform your BTH calculations and think you have a handle on the capacity, but the owner and you think a load test would be helpful, would the load test use a 2.0 safety factor to create the actual load used in the test? Or would you use the 3.0 factor? Or would you use something higher?
If you view the typical 2.0 factor in the IBC as an increase on the typical safety factor of 1.66 used in design, then the IBC is essentially suggesting that loads used in load tests are 2.0 / 1.66 = 1.2 more than typical.
1.2 times the BTH factor of 3.0 leaves you with 3.6 to be used in the load test to verify a BTH designed assembly.
What would be appropriate? The BTH-1 document doesn't appear to speak to in-situ load tests for verification of capacity.
In those sections they typically require a load to be applied to a structure in excess of the design load. The IBC, in section 1713, requires a load of 2 times the design load to be used.
This then is essentially a safety factor of 2.0.
In the ASME BTH-1 document, for say a hanging assembly to lift materials up to a higher level during construction, the BTH requirements for design use higher safety factors
than typical...say 3.0.
The question: If you are trying to verify the safety of an assembly that is already built, and you perform your BTH calculations and think you have a handle on the capacity, but the owner and you think a load test would be helpful, would the load test use a 2.0 safety factor to create the actual load used in the test? Or would you use the 3.0 factor? Or would you use something higher?
If you view the typical 2.0 factor in the IBC as an increase on the typical safety factor of 1.66 used in design, then the IBC is essentially suggesting that loads used in load tests are 2.0 / 1.66 = 1.2 more than typical.
1.2 times the BTH factor of 3.0 leaves you with 3.6 to be used in the load test to verify a BTH designed assembly.
What would be appropriate? The BTH-1 document doesn't appear to speak to in-situ load tests for verification of capacity.
