rlewistx
Structural
- Jun 21, 2003
- 98
I’m working on the design of a mechanical room housing refrigeration equipment. It must be designed for explosions per FM 1-44. The room is located adjacent to the warehouse. It shares a common wall with the warehouse and has 3 independent walls. The wall farthest from the warehouse is the explosion relief wall. It is constructed from metal wall panels and will have a release pressure of 20 psf. The other 3 walls have to be explosion resistant per FM. The design pressure is 70 psf. I am using concrete wall panels since I have tilt-up elsewhere on the project. The party wall with the warehouse will be concrete as will the two walls that are perpendicular to the warehouse endwall. This makes a 3 sided box. FM 1-44 requires the walls to be non-bearing and have a steel or concrete frame backup. I will have a steel frame backup.
I would like some feedback from others who have designed explosion resistant construction. I’m wondering about lateral stability of the mechanical room framing. For wind and seismic loads the 3 sided box works great for lateral stability. Can the walls also be used for lateral stability during an explosion? Section 3.1.8 “Pressure Resistant Construction Details” of FM 1-44 seems to imply there needs to be a frame to backup the wall panels. Section 3.1.9 “Steel Walls and Framing” discusses steel frame backup for concrete masonry but does not mention concrete walls. Can the walls also be used for lateral stability, or do I need a braced frame in the backup steel?
A parallel consideration is the roof deck. Is a regular roof deck with insulation typically provided, or is concrete filled deck typically provided in explosion resistant construction? I’m wondering if the roof diaphragm would be in tack sufficiently to provide a diaphragm after an explosion if it is not filled. It seems to me the weight of the concrete will help resist the uplift of the explosion force so that the diaphragm will remain in tack and able to resist shear. The negative factor is the added cost from concrete and the steel and foundation to support the weight of the concrete. If the roof is not designed to release pressure, should it be concrete filled?
FM 1-44 does not mention how to determine the forces needed for lateral stability. It seems to me the forces on the 2 side walls of the 3 sided box would primarily be equal and opposite. The back side of the box that separates the warehouse from the mechanical room would have the force of the explosion of 70 psf. What other ways are there of looking at the lateral stabilizing force for the overall system?
Thanks for any insight you may be able to give.
Rich
I would like some feedback from others who have designed explosion resistant construction. I’m wondering about lateral stability of the mechanical room framing. For wind and seismic loads the 3 sided box works great for lateral stability. Can the walls also be used for lateral stability during an explosion? Section 3.1.8 “Pressure Resistant Construction Details” of FM 1-44 seems to imply there needs to be a frame to backup the wall panels. Section 3.1.9 “Steel Walls and Framing” discusses steel frame backup for concrete masonry but does not mention concrete walls. Can the walls also be used for lateral stability, or do I need a braced frame in the backup steel?
A parallel consideration is the roof deck. Is a regular roof deck with insulation typically provided, or is concrete filled deck typically provided in explosion resistant construction? I’m wondering if the roof diaphragm would be in tack sufficiently to provide a diaphragm after an explosion if it is not filled. It seems to me the weight of the concrete will help resist the uplift of the explosion force so that the diaphragm will remain in tack and able to resist shear. The negative factor is the added cost from concrete and the steel and foundation to support the weight of the concrete. If the roof is not designed to release pressure, should it be concrete filled?
FM 1-44 does not mention how to determine the forces needed for lateral stability. It seems to me the forces on the 2 side walls of the 3 sided box would primarily be equal and opposite. The back side of the box that separates the warehouse from the mechanical room would have the force of the explosion of 70 psf. What other ways are there of looking at the lateral stabilizing force for the overall system?
Thanks for any insight you may be able to give.
Rich
