Ideas to Make over Cobo Center

[Stosh]

You cannot just place an intricate green roofing system on an unreinforced structure. The added weight drastically changes the Dead Loads, and puts a further strain on Live Load capability.

It's reinforced due to the parking above already allotted for. Subtract cars, add system.

[ghettopalmetto]

It's reinforced due to the parking above already allotted for. Subtract cars, add system.

As I [[thought I) stated, design live loads for parking cars is 50 psf. You allow people up there, and you have to bump it up to 100 psf [[above any dead load for green roof materials). I don't know how you think you can just magically achieve 50 psf of extra load-supporting capacity, but I'm sure that if you wish it hard enough, it can happen.

But maybe we should try it your way first. I wouldn't want to be called closed-minded. Just let us know at what point the whole damned roof falls in.

[Stosh]

As I [[thought I) stated, design live loads for parking cars is 50 psf. You allow people up there, and you have to bump it up to 100 psf [[above any dead load for green roof materials). I don't know how you think you can just magically achieve 50 psf of extra load-supporting capacity, but I'm sure that if you wish it hard enough, it can happen.

But maybe we should try it your way first. I wouldn't want to be called closed-minded. Just let us know at what point the whole damned roof falls in.

That would solve the Cobo problem, wouldn't it?

And I don't follow your math either. Say a parking lot of cars, each weighing over 2000 pounds each, runs a live [[excuse me) load of 50 psf. How many humans would you pack on that roof to equal a doubling of that load?

[ghettopalmetto]

And I don't follow your math either. Say a parking lot of cars, each weighing over 2000 pounds each, runs a live [[excuse me) load of 50 psf. How many humans would you pack on that roof to equal a doubling of that load?

It's not math. It's the requirements of the building codes.

[Stosh]

It's not math. It's the requirements of the building codes.

So would it make any difference if there were not people allowed up there? There are people up there now when cars are parked up there, when a show lets out, fireworks, etc. Load requirements for parking garages elsewhere have dropped to 35-37 psf in some localities lately.

[ghettopalmetto]

So would it make any difference if there were not people allowed up there? There are people up there now when cars are parked up there, when a show lets out, fireworks, etc. Load requirements for parking garages elsewhere have dropped to 35-37 psf in some localities lately.

Yes, it changes quite a bit. Areas of assembly and pedestrian corridors must have a minimum live load capacity of 100 psf. This does not include the self-weight of the structure, rooftop HVAC equipment, or snow loads on a roof surface [[which, in Detroit, are at least 30 psf alone).

Please cite your source of information regarding the parking garages that have been designed to 35-37 psf. Michigan uses a statewide building code that does not allow localities to opt-out of particular provisions. The Michigan Building Code is essentially the same as the International Building Code [[2006 is the current version), with state-specific amendments. The International Building Code [[which incorporates ASCE 7 by reference) requires a minimum design live load of 50 psf for parking decks. I don't know any engineer willing to stake his career, or the public safety, on using a lower design value.

[gumby]

One day the Frank Gehry "crushed trashcan" look may get a different response... such as "what were they thinking when they built that?"

Some of us already make that statement..

[Stosh]

Yes, it changes quite a bit. Areas of assembly and pedestrian corridors must have a minimum live load capacity of 100 psf. This does not include the self-weight of the structure, rooftop HVAC equipment, or snow loads on a roof surface [[which, in Detroit, are at least 30 psf alone).

Please cite your source of information regarding the parking garages that have been designed to 35-37 psf. Michigan uses a statewide building code that does not allow localities to opt-out of particular provisions. The Michigan Building Code is essentially the same as the International Building Code [[2006 is the current version), with state-specific amendments. The International Building Code [[which incorporates ASCE 7 by reference) requires a minimum design live load of 50 psf for parking decks. I don't know any engineer willing to stake his career, or the public safety, on using a lower design value.

Sorry. I was quoting speculation on a message board, here's a more realistic number. Still, 40 is a big reduction.
http://www.gostructural.com/magazine...oads-4221.html

Section 1607.9: Passenger Vehicle Parking Garage Live Loads
February 2006 » Columns » CODE SIMPLE

The International Code Council's 2003 International Building Code [[IBC) Table 1607.1, Item 16, sets forth a uniform live load of 40 pounds per square foot [[psf ) for passenger vehicle parking garages.
By S. K. Ghosh, Ph.D., Susan Dowty, S.E.
The International Code Council’s 2003 International Building Code [[IBC) Table 1607.1, Item 16, sets forth a uniform live load of 40 pounds per square foot [[psf ) for passenger vehicle parking garages, and "Footnote a" requires that garages restricted to vehicles accommodating not more than nine passengers be designed for a concentrated load of 3,000 pounds acting on an area of 4.5 inches by 4.5 inches. Both of these live loads were revised from those specified in the 2000 IBC, which were a live load of 50 psf and a concentrated load of 2,000 pounds acting on 20 square inches. The rationale for changing the live loads was based upon a publication which is available from the American Society of Civil Engineers [[ASCE), Design Live Loads for Parking Garages: A Report to the Structural Engineering Institute of the American Society of Civil Engineers by Y.K.Wen and G.L.Yeo.This study justified a reduction in the live load from 50 psf to 40 psf and an increase in the concentrated load due to very heavy passenger vehicles such as sport-utility vehicles. The 2003 IBC-prescribed loads are the same as those in ASCE 7-02 and —05, Minimum Design Loads for Buildings and Other Structures.

[ghettopalmetto]

I don't have IBC 2003 handy right now, but the way that article reads, it's not just a reduction to a uniform 40 psf live load from 50 psf. You also have to design for a 3000 lb concentrated load over a 4.5" x 4.5" area in addition to the uniform 40 psf surface live load.

Rather than design for the concentrated load in addition to the surface live load, the design engineer may be just as likely to use a uniform surface live load of 50 psf in his design.

[Stosh]

I would imagine so, but I'm no engineer, obviously. So I'd be more than happy to see the standards spelled out in the future, in code. And there's differences in "green" roof systems to consider as well. An extensive roof has a different characteristic than a intensive one. I'd think that the only way any kind of green roof on Cobo is an extensive one.

Here's a good PDF laying out certain restrictions if you are interested.
http://www.cityofberkeley.info/uploa...f%20System.pdf

[Stosh]

Also for information purposes, Minnesota's target center is beeing considered for a green roof as well. Quite informative.

http://www.ci.minneapolis.mn.us/coun...21-2-11-08.pdf

[ghettopalmetto]

The only real limitations to a green roof on Cobo, other than the nature of plants that will grow in Detroit's climate, are structural. And even those limitations can be overcome, depending on how much money the regional authority is willing [[or able) to spend on reinforcing the roof structure.

[Stosh]

It's all about money. Keeping the parking deck and superinsulating the ceiling past the reccomended R-38 would save them some operating cash as well. Either way, whatever works. And I'd love to see them use the river for some geothermal action as well. But, that's for another discussion.

[wolverine]

I don't think these green roofs have to be all that substantial.

There are three buildings across the street from me that have USGBC defined green roofs. One of them is a parking structure that has the very top floor as retail. The roof was not originally designed for a green roof or any more retail or parking levels. It contains flats of native plants that are on lightweight trays.... mostly grasses.

This neighboring department store has a similar configuration

[MichMatters]

This is not to mention the gigantic green roof atop one of the River Rouge factories, which isn't built much differently than the warehouse/airplane hanger that is Cobo.

[d.mcc]

This is not to mention the gigantic green roof atop one of the River Rouge factories, which isn't built much differently than the warehouse/airplane hanger that is Cobo.

That building was completely redesigned and rebuilt. Its not as if they just put down some insulation and a moisture barrier and put some sod up there...

[Detroitnerd]

Are you suggesting green roofs are a fad?

It'll take a while to see. I see lots of neat stuff that looks pretty forward thinking, but I'm not sure all applications make sense. A lot of the time it's a fig leaf [[Ford is a huge polluter looking to score a PR win) or a gimmick [[the "green roof" might help build buzz for a Cobo deal). Or, I grant you, it could be my hyperactive cyncism hard at work.

[d.mcc]

It'll take a while to see. I see lots of neat stuff that looks pretty forward thinking, but I'm not sure all applications make sense. A lot of the time it's a fig leaf [[Ford is a huge polluter looking to score a PR win) or a gimmick [[the "green roof" might help build buzz for a Cobo deal). Or, I grant you, it could be my hyperactive cyncism hard at work.

Because I am pretty sure green roofs have been around as long as man has been constructing shelters for himself. I don't know if Terra Amata had any "green" or "living roofs" persay, but I am fairly certain that were in use at Scara Brae.

[Detroitnerd]

Because I am pretty sure green roofs have been around as long as man has been constructing shelters for himself. I don't know if Terra Amata had any "green" or "living roofs" persay, but I am fairly certain that were in use at Scara Brae.

That's true. But you must admit that, these days, there's a novelty factor to LEED-approved design and green roofs. Hell, work around urban planning issues long enough, and you see how faddish and fleeting all that "novelty" can be.

A short history of an American thoroughfare:

1950s: Take out the streetcar for traffic.

1960s: Widen the thoroughfare for smoother traffic.

1970s: Build out the sidewalk in hopes of attracting more shoppers.

1980s: Add a streetscape to fill the empty shopping sidewalk.

1990s: Take out the streetscape because it looks dated.

2000s: Add a median for "green space."

When I think of all the money that's spent on this "great new idea" over the last 60 years, I wonder if we shouldn't have just kept the streetcars instead of spending $50 million here and $100 million there on the latest "sure thing."

Then again, you know cynical ol' me.

[Stosh]

That's true. But you must admit that, these days, there's a novelty factor to LEED-approved design and green roofs. Hell, work around urban planning issues long enough, and you see how faddish and fleeting all that "novelty" can be.

A short history of an American thoroughfare:

1950s: Take out the streetcar for traffic.

1960s: Widen the thoroughfare for smoother traffic.

1970s: Build out the sidewalk in hopes of attracting more shoppers.

1980s: Add a streetscape to fill the empty shopping sidewalk.

1990s: Take out the streetscape because it looks dated.

2000s: Add a median for "green space."

When I think of all the money that's spent on this "great new idea" over the last 60 years, I wonder if we shouldn't have just kept the streetcars instead of spending $50 million here and $100 million there on the latest "sure thing."

Then again, you know cynical ol' me.

That's true. But then again not a single "great new idea" listed here ever saved a penny in energy costs. This will, at least for cooling. And the insulation on the bottom will boost efficiency as well, overall.

[Detroitnerd]

That's true. But then again not a single "great new idea" listed here ever saved a penny in energy costs. This will, at least for cooling. And the insulation on the bottom will boost efficiency as well, overall.

For a building that's used a few weeks out of the year ... but heated and cooled every day?

[Stosh]

For a building that's used a few weeks out of the year ... but heated and cooled every day?

Especially so. I wonder how much of their operating costs go up and out through inefficiencies every year? And there's no income coming in? Lovely.

[Detroitnerd]

Am I the only one who sees the "green roof" as a fig leaf for a space-hogging facility downtown that's used a few times a year? Am I alone in feeling we demolish buildings that could be turned into showpieces and tack on questionable "green" benefits for buildings that really are wasteful?

Well, at some point, you have to admit that the PR outweighs the reality.

[Stosh]

Am I the only one who sees the "green roof" as a fig leaf for a space-hogging facility downtown that's used a few times a year? Am I alone in feeling we demolish buildings that could be turned into showpieces and tack on questionable "green" benefits for buildings that really are wasteful?

Well, at some point, you have to admit that the PR outweighs the reality.

Yes, you are.

But seriously, can you honestly name any of these so called "showpieces" that are energy efficient? One that brings in income? One that brings in tourists and their dollars [[besides the ruin tourists)? There's real reasons why these buildings sit or are demolished, it's not cost effective to run them.

The perception may be overblown, green may be a lot of PR, but energy efficiency is a real consideration for more than a few people. It's the bottom line for a lot of people, and that's all that counts in the real world.

[Detroitnerd]

Can you honestly name any of these so called "showpieces" that are energy efficient? One that brings in income? One that brings in tourists and their dollars [[besides the ruin tourists)?

They call it "building the cathedral just for Easter." It's used a few times a year and takes up so much precious downtown space. I'd rather have many things there in its place: a downtown rail depot, for instance. Honestly, I would even gladly trade Cobo in a heartbeat for five or six factories that produce moderate pollution.

The perception may be overblown, green may be a lot of PR, but energy efficiency is a real consideration for more than a few people. It's the bottom line for a lot of people, and that's all that counts in the real world.

Conservation is important, but some things just aren't worth conserving. I think Cobo is a good example: Political football, managerial disaster, white elephant, Goliath resource-sucker, and all for a week a year. But, more to your point, I think good things are often used in the defense of bad things. Take the whole "green" thing: Once any term or tactic has a sheen to it like "green" does, you can use it to push the brownest stuff out there. Those are my concerns.