Structural Elements Explosion Loads Design

[JoeH78]

I need to design structural shear wall for explosion of boiler room structure, in structure will be:

1. Thermal Oil Heater

Operating pressure 6 bar,
design pressure 15bar,
oil flow rate 64m3/h )
Vertical
698 KW​

2. Expansion Tank

Capacity : 3000 liter
Operating pressure 1 bar,
design pressure 9 bar,
DEsign Temperature 280C​

3. Storage Tanks ( 2 Units)

Operating pressure Atmospheric
DEsign Temperature 95C​

Based on that, it seems that expansion tank and oil heater are the most dangerous in case of explosion, how am ı supposed to calculate that explosion load?

 

[GeorgeTheCivilEngineer]

Might be able to work out the peak pressure by looking at the volume of the room, and the volume of released gases. when they combust. Or, talk to the manufacturer.

Disproportionate collapse and key element removal might be a good idea too.

 

[JoeH78]

Might be able to work out the peak pressure by looking at the volume of the room, and the volume of released gases. when they combust. Or, talk to the manufacturer

I'll talk to manufacturer but just wanted to talk with the community beforehand, especially to know if there was any amprical formulation or reference to any code/regulation. In past I've done that lateral shear wall design which will sustain 5kN/m2 lateral loads automotive industrial building, but I couldn't get in touch with designer on what premises they choose to have 5kN/m2.
Code or regulation reference is what I'm needing and this is what client demands from me.

Disproportionate collapse and key element removal might be a good idea too.

Absolutely it's good idea, I'm planing to leave outer wall and roof for blast release other walls will be very rigid.

 

[GeorgeTheCivilEngineer]

The accidental characteristic action a key element needs to resist in Eurocodes is given as 34kN/m^2 (historically I believe this was from the British Standards, which used 34kN/m^2 for buildings containing gas appliances, 17kN/m^2 for non-gas - now is all 34kN/m^2). So that might be the order of magnitude you're looking at.

When I've designed a couple of substations I can't remember the blast load - might have been 5kN/m^2 as well actually - but it had to be stronger than the force it'd take to remove the timber roof. Thinking being that they wanted the blast force to go upwards, rather than spreading masonry sideways (into the hospital walls/windows). At the same time I was looking at a job where the architect had given the substation a green roof....... creating a fantastic potential bomb.

 

[ThomasH]

Hello
I have done some explosion design in different projects. I don't thing you have the data you need to calculate the static equivalent load. The simplest/best approach for your problem is probably to work with pressure release openings.

Typically for an explosion you have overpressure (kN/m2) and duration (time). That means that the structure responds dynamically and you can't determine the static eqvivalent load based on the load alone, you have to consider the structure as well. The load 34 kN/m2 comes from the Ronan Point accident in November 1968,

https://en.wikipedia.org/wiki/Ronan_Point.

That load is often used as static equivalent load for an explosion. But I think that value should be used with some care based on what I just wrote. Still, it is in some codes so it can be valid in some cases.

Thomas

 

[le99]

I think the "Design of Blast-Resistant Buildings in Petrochemical Facilities" is a must-read. Available on ASCE Link, or Ebay Link

 

[ThomasH]

I think the "Design of Blast-Resistant Buildings in Petrochemical Facilities" is a must-read. Available on ASCE Link, or Ebay Link

I agree, it is a good reference. But I believe it has primarily info on external explosions.

Thomas

 

[JoeH78]

@ThomasH

I have done some explosion design in different projects. I don't thing you have the data you need to calculate the static equivalent load.

What other data do I need to obtain in order to calculate the explosion load? If its not documented in the previously listed data then I'll request them from client. I'm sure that they will supply it.

I obtained the "Design of Blast-Resistant Buildings in Petrochemical Facilities" by the way. And I'll read it.

 

[ThomasH]

What other data do I need to obtain in order to calculate the explosion load?

Most of my explosion design has been with external explosions. For internal explosions I have usually used blast release openings. There are methods described in the Eurocode for that.

My concern is that I don't think the data you have gives you info regarding the energy released in case of an explosion. But since I don't know the process I may be wrong. I would try to explain the problem to the client and see if it can be solved together with the client.

Thomas

 

[WARose]

Every time I've figured a blast load due to the possibility of equipment failure, it has started with the equipment vendor....and they have given me a (equivalent) explosive charge. So I'd start by asking them.