Anchor/mounting requirements for equipment up on mezzanines?

[bill1952]

Agree with Yankee Chronicler and ClassicT. I design theatres typically with a stage. I estimate there are 40,000 to 50,000 theatres in the US, the vast majority in high schools. They have stage equipment - lighting, curtains, tracks, screens, etc. - hanging over heads. Not one word in IBC nor LSC about the installation or design of this gear other than "the building structure has to be designed to support the loads it is intended to carry". On projects I'm involved with I'm providing those loads to the structural engineer. I have also seen enough stages - primarily public high schools - where the structure was not designed for the loads. Sagging bottom chords of bar joists and bar joists rolled to the side.

Get the info from the manufacturer and give it to the structural engineer.

 

[Mark K]

Agree with Yankee Chronicler and ClassicT. I design theatres typically with a stage. I estimate there are 40,000 to 50,000 theatres in the US, the vast majority in high schools. They have stage equipment - lighting, curtains, tracks, screens, etc. - hanging over heads. Not one word in IBC nor LSC about the installation or design of this gear other than "the building structure has to be designed to support the loads it is intended to carry". On projects I'm involved with I'm providing those loads to the structural engineer. I have also seen enough stages - primarily public high schools - where the structure was not designed for the loads. Sagging bottom chords of bar joists and bar joists rolled to the side.

Get the info from the manufacturer and give it to the structural engineer.

The failure modes noted likely are more the result of how the loads were applied to the bar joists than whether the bar joists could have supported the loads if properly applied. The structural engineer should be sensitive to those issues

Stages present a special challenge since the individuals hanging the lights and other equipment likely do not have an engineering education and probably do not understand the need to obtain a permit.

 

[ICE]

have an engineering education

I've hired a few engineers...as carpenters and auto mechanics. The Engineering Degree was not the deciding factor...I just figured that they might be smart. Some were.

 

[bill1952]

The failure modes noted likely are more the result of how the loads were applied to the bar joists than whether the bar joists could have supported the loads if properly applied. The structural engineer should be sensitive to those issues

Stages present a special challenge since the individuals hanging the lights and other equipment likely do not have an engineering education and probably do not understand the need to obtain a permit.

Or the bar joists were not designed for the loads because no one thought about it. As a theatre consultant I provided loading information to the engineer, and illustrated the attachments. The theatre user shouldnt have to be an engineer if it's designed correctly.

The problem is registered design professionals don't know what happens on a stage and don't know they don't know. That's why they should consult with someone who does.

 

[Mark K]

Or the bar joists were not designed for the loads because no one thought about it. As a theatre consultant I provided loading information to the engineer, and illustrated the attachments. The theatre user shouldnt have to be an engineer if it's designed correctly.

The problem is registered design professionals don't know what happens on a stage and don't know they don't know. That's why they should consult with someone who does.

It is not clear that the engineer screwed up. Further the engineer is typically only active on the project during the time that the permitted work is in process. The Engineer would not have any way to know what changed after his work was done.

There is no expectation that the theater users be engineers, but it would be good practice for the stage crew to have guidelines to help them identify when an engineering review is needed. Too expect the engineer to anticipate all possible situations is not reasonable. Be careful before you cast the first stone.

 

[CaiusFlint]

Chapter 16 essentially says the building structure has to be designed to support the loads it is intended to carry. If the original design knows there will be an especially heavy machine placed at a specific location within the building, the engineer designs the floor (or mezzanine) to support that load, as either a distributed or concentrated load as appropriate.

The code says nothing about how the machine gets anchored to the building.

Yeah, that was the only chapter I found as well. Plenty of specs on anchoring sub-structures to the building (platforms, mezzanines, etc.), but nothing I found on anchoring anything to that sub-structure, that one happens to place on top of it. Simply, that it falls within load calc specifications.

 

[Mark K]

I suggest that people are too narrowly interpreting the provisions in the IBC and are ignoring reference standards such as ASCE 7.

 

[bill1952]

It is not clear that the engineer screwed up. Further the engineer is typically only active on the project during the time that the permitted work is in process. The Engineer would not have any way to know what changed after his work was done.

There is no expectation that the theater users be engineers, but it would be good practice for the stage crew to have guidelines to help them identify when an engineering review is needed. Too expect the engineer to anticipate all possible situations is not reasonable. Be careful before you cast the first stone.

In my 40+ years of experience, this is equipment installed as part of the general contract, certainly during the time that the permitted work is in process". If it's labeled a stage doesn't the engineer have some obligation to ask what if any loads will be imposed?

 

[Yankee Chronicler]

In my 40+ years of experience, this is equipment installed as part of the general contract, certainly during the time that the permitted work is in process". If it's labeled a stage doesn't the engineer have some obligation to ask what if any loads will be imposed?

Asking what loads will be imposed is an entirely different question that asking how those loads will be attached. Especially if the equipment will be op top of the mezzanine (as in this example), the question asked wasn't whether or not the mezzanine is capable of holding up the weight of the conveyor system (plus the anticipated weight of whatever will be conveyed along the conveyor system). The question was about how to attach the conveyor support legs to the mezzanine.

There is nothing in the IBC that addresses this. Mark K mentioned ASCE 7. Yes, The IBC refers (or defers) to ASCE 7 for the nitty gritty of structural design. Mark, since you mentioned it, please tell us exactly where ASCE 7 addresses how the support legs of a conveyor system should be attached to the floor on which they rest.

 

[Penguin87]

Needs an engineer to design the equipment anchorage, always.

The anchorage allowed depends on the risk category for the building and seismic design category for your building, as well as the weight of the equipment. Where I practice, on the west coast, most of our buildings fall into a seismic design category D, which means anything over 450# needs to be seismically anchored. This means anchorage to structure with design attachments - typically lots of bolts to structural beams or angles.

YMMV, Ohio has a much lower seismic risk.

 

[classicT]

I suggest that people are too narrowly interpreting the provisions in the IBC and are ignoring reference standards such as ASCE 7.

Mark, seems like consensus is not of the same opinion.

 

[Mark K]

Asking what loads will be imposed is an entirely different question that asking how those loads will be attached. Especially if the equipment will be op top of the mezzanine (as in this example), the question asked wasn't whether or not the mezzanine is capable of holding up the weight of the conveyor system (plus the anticipated weight of whatever will be conveyed along the conveyor system). The question was about how to attach the conveyor support legs to the mezzanine.

There is nothing in the IBC that addresses this. Mark K mentioned ASCE 7. Yes, The IBC refers (or defers) to ASCE 7 for the nitty gritty of structural design. Mark, since you mentioned it, please tell us exactly where ASCE 7 addresses how the support legs of a conveyor system should be attached to the floor on which they rest.

ASCE 7 and other reference standards do not provide proscriptive provisions for all situations. Rather they provide the engineer with provisions for establishing loads and how the resulting forces can be resisted. Typically an engineer is needed to determine the solution since it is likely to be case specific.

 

[Mark K]

To repeat, the code does not provide a specific solution for every case but it does require that for every case the solution be adequate.

While in some cases the code may provide a prospective solution, in many cases the code does not provide a prospective solution.

The code defines the loads/forces that must be considered. Other parts of the code, including reference standards, provide provisions that enable one to determine if the members and connections are adequate to resist the loads/forces. The reality is that unless you have the training of an engineer it is likely to be very difficult for aa non engineer to be able to show that the final solution is adequate to resist the required loads/forces.

Sometimes an engineer will provide drawings that provide guidance for common situations. These typical details will be valid for a particular project but should not be assumed to be adequate for other projects.