Designing a Church 1

[user2006]

Hi Guys,

I am designing a 25,000 sq. ft. church in California (Lancaster, Los Angeles), the roof is going to be wood truss so I have no problem with that (as far as the design …).

please follow the link below which will lead you to a PDF file including some floor plans, elevations and sections of this project.

http://groups-beta.google.com:80/group/download_my_files?hl=en

(The file name is the-church. PDF, you can do right click and save it to your computer.)

Here are the most preliminary questions that came to my attention:

1- At the main building there is no walls and columns on the middle, will it be okay if I consider just the exterior walls to transfer the shear loads?(what else I can do?)
2- Do I need to use concrete block wall or wood stud wall would be fine?
3- How should I design the glass frame under the roof because they suppose to transfer both shear and vertical loads?
4- What do I need to know about designing the tower?


Because it is my first time doing such a project your comments and inputs are greatly appreciated regarding the most important things I should concern about. Thanks,

Regards,
User2k6

 

[scottiesei]

Hmmmm....your questions make me very nervous, especially for such an important structure. Find someone experienced near you and work under them.

 

[dik]

I think scottie... has some valid concerns in particular with high human occupancy... perhaps considered as an act of God?...

Regarding your questions, I'm speaking from an engineering focus and not requirements of your jurisdiction.

The roof truss system can be designed as a diaphragm transferring loads seismic, dead and live to the side walls.

The side walls can be constructed using wood stud and sheathing, etc. or as masonry (if permitted). If masonry is used a portion of the wall can have a diaphragm with the balance of the masonry being isolated so that it doesn't form part of the main resisting seismic structure.

As far as the tower is concerned, this can be tied into the roof and any intermediate floors and can be constructed as a wood/masonry diaphragm, putting loads into the roof and intermediate floors. You may want to talk the owner out of too large or imposing tower... they tend to be located near exits and given a seismic event, this could trap/crush parishoners.

Dik

 

[Lutfi]

I must say that Scottie and dik are right on target. This is a serious structure and considering the intended use, well, I would seriously consider asking for help from a more senior engineer.

EOM


Regards,
Lutfi

 

[JStephen]

I'd suggest for one thing that you make sure you are complying with engineering licensing laws in CA (and, for that matter, architecture laws). If you're unlicensed, or just not that familiar with building design, find someone that is. That should help, not only in getting things done right, but avoids reinventing the wheel, exploring options that ultimately have to be rejected, deciphering the building codes, etc. Even if you're licensed to do the work in general, there's no reason not to get imput or a review from an engineer more experienced with this design, even if you do some or most of it.

 

[dik]

I tend not to get into issues regarding licensing laws... professional integrity should preclude this. The old adage, "If you have a PR department, then, you're doing something wrong." Best to point out some of the issues...

 

[JStephen]

Unfortunately, people who are not licensed or seeking licensing tend to be unfamiliar with the licensing laws as well, which is why I bring the subject up.

I've seen several disciplinary cases through the years involving church design. Churches often have limited finances and willing volunteers, and that can lead to problems in engineering and architecture.

 

[user2006]

Hi Guys,

Thanks for your comments (specially Dik), I am PE but as I mentioned before I haven't done this kind of projects,... so please lets talk about engineering issues and comments.

Thanks again.
U2k6

 

[rb1957]

in that case, i'd refer you to the earlier posts, about linking up with someone who can advise you face-to-face ... the issues you want to discuss are so fundamental (and general) that i don't think they can be reasonably discussed in a free forum. when it comes to designing a biulding, I'd have thought that the codes define everything that you need and probably much more so (so you need some knowledge, or someone with knowledge, to help you with your design).

I appreciate that you are a PE (you say so, good enough) and I suspect that you're helping out some friends. As a PE would you sign for something unless you know it's right ? As a PE, I think you've a greater burden of responsibility that someone who isn't.

anyways, good luck

 

[COEngineeer]

Our firm design residential and light commercial buildings. There is no way we would bid on a 10 stories building because we dont have the experience. Yes, we probably can design it, but the learning curve will proabably make the project not very profitable.

Anyway, it looks like the glass frame isnt supporting any roof load (unless you have ridge/valley beam land on the header, i hope not). So all you have is a little weight from the lookout. Just have to look at lateral pressure from wind I think.

 

[whyun]

Whether a structure is 1 story or 5, structural principles remain the same. Start with gravity element design from the unsupported element and trace the load down all the way to the foundation. Once you have a gravity system, layout and design the lateral elements starting from the roof diaphragm all the way down to the foundation designing all elements/connections along the way.

The solution is in the "details". Hook up with an engineer who has done this type of structure before and get some ideas as to standard details that may be appropriate for structure of this type.

If I were doing this project, I would select a bearing+shear wall system using concrete blocks, steel interior columns and beams where needed and a plywood diaphragm. There may be other ways to disect a cat.

 

[user2006]

Defiantly I would ask someone with more experience to help me with it, I haven't thought that I shouldn't have posted my questions here because this is a free forum.
I was looking for some comments like what Dik or COEngineer have mentioned ... but I learned many other things as well which is good!.

Thanks anyway.

 

[civilperson]

The California laws require an SE to the principal Engineer of Record for buildings of a given size and larger. As PE you are not to supposed to be the lead for large projects.

 

[whyun]

Last time I checked, SE is required for design of public schools and acute care hospitals in California. I "heard" of a height limitation but was unable to find it in hard print.

Institutional structure of this size, in my opinion, can be designed by a PE but check with the local building official as they may have more stringent requirements than the state laws.

 

[DonPhillips]

You need to invest in a copy of your state building code. Based on the size of the building and its location on the lot, you may have limited options on Types of Construction which could rule out light-frame wood construction. You may have fire suppression requirements which will increase some of the loads on the strucuture, and you will have ventilation requirments that may need to be accounted for.

The code will tell you your seismic requirements which may help you figure out your lateral loads and methods of transfer and the loads on the steeple (aka tower). Typically, ASCE-7 in most states.

Don Phillips

http://worthingtonengineering.com

 

[dik]

Is there a distinction between an SE and a PE? and is it local to a jurisdiction?

Dik

 

[DonPhillips]

Some states license engineers by specialty and I think CA is one of them. Others generically license engineers. An SE in CA needs to take an extra exam, if I recall.

Don Phillips

http://worthingtonengineering.com

 

[dik]

User2006... your posting was totally appropriate... and welcomed by the crowd...

DonPhillips... wrt California... just going through a mess of fairly technical seismic stuff... my own refresher... thanks

Dik

 

[JStephen]

I was over checking out the CA rules. I can't find a height limitation anywhere, but I'm pretty sure it was there when I checked into CA registration a number of years back. I assume it has been removed. Anyway, I seem to remember it was 200'.

In reading through the rules, it looks like CA mainly regulates the use of the title of SE, as opposed to the practice. Then it looks like the requirement for SE on hospitals and schools come from two separate rules regulating hospital and school construction, and not from the state engineering rules themselves.

One thing we'd run into back then was that most of our customers in CA would specify a SE seal on drawings, even if state rules didn't require an SE.

 

[DonPhillips]

If CA is using the IBC, depending on the Type of Construction, there may or may not be a height restriction, depending on use. Churches are A-3 and you may be limited in height of habitable space. If I recall, even the UBC had similar language based on type of construction. Type I buildings typically are unlimited in area and height.

Zoning is another issue. Most jurisdiction that have a zoning code limit height. A variance could be sought pretty easily for a church.

Of course, a floor greater then 75' above the level of egress qualifies it as a high rise building and all of the associated extra safety features. A steeple would not be habitable so would not kick in the high rise requirements.

I can see why a customer may want an SE depending on the project and it makes sense that buildings housing children, and hospitals needed during an emergency would have a state law requiring what some customers choose to do. I can see public buildings wanting to save a few bucks by shorting the dollars available for design if no law prevented them.

Don Phillips

http://worthingtonengineering.com