Shoring Alternative from Craig!

fyi - an alternate shoring design that Rob Ward is advocating for house addition in west seattle I'm working on. 

From: John McDowell [mailto:JohnM@PileKing.com]
Sent: Tuesday, June 28, 2011 7:19 AM
To: croberts@ctengineering.com
Subject: driven wide flange shoring

Hi Craig,

Please see attached a general description of the driven wide flange shoring system as well as a few pictures of jobs we have done.

Beams are driven using a hydraulic impact hammer that strikes the pile at about 250-400 blow per minute.  For temporary cuts up to 8’ cantilever we oftentimes see W6x25 beams at 2’ centers, but for deeper excavations we recommend a W8x31 or W8x35.  Lastly, the maximum length beam we can drive without a splice is 30’.

At the end of the job beams are left in the ground as sacrificial.  If necessary beams may be cut off several feet below grade to insure they don’t interfere with future landscaping.

If you have any comments or questions then please do not hesitate to call or write.

Regards,

 John McDowell

       McDowell

Pre fabricated wood stairs

Here are a few photos from my "Seattle stair and design" field trip last Friday afternoon. Contact information on card photo.

These guys are craftsmen to say the least and have been in business in the local area for around 30 years.

If this post works I can follow up with some more information.

Ben

Check the links to the CTE blog

You all should be getting the links to postings whenever they now arise... (there were some bugs!)

Should all be good now!

Mech'l Equipment - Design requirements

Kudo's to Anne for info on this topic.

The graphic from "mybuildingpermits.com" is very helpful. This seems to imply in some cases that we should be providing design support for some items over 75 pounds.... WTH!!!

It may be that this issue should come to a head... Due to the "unknowable nature" of some of these items, maybe we should be specifically excluding these items from our design services, and insert them as an additional service on an hourly basis... There is no way that our clients will know that we have to do all this crap... if we seperate it out, maybe they will...?  any thoughts?

PT Design and standards in the CT Office

So the question has come up over the last few weeks about PT design and bonded rebar in PT slabs.

The current status of the CTE design philosophy is wrapped up in a FE calc done using RAM Concept that typically aims at the minimum prestress levels required by code. Code requires 125psi min in slabs... we generally aim at 150 to 200psi depending on column layouts, significant on-off spans etc...

As you know, the benefits of maintaining the code min prestress is that you get to "write-off" some of the "speed-bumps" that you'd otherwise run into for normal RC design... such as min bonded rebar spacings, distribution of rebar in beams and slabs, requirements for 2-way slabs and so on. So its important to get those benefits when designing PT. However, it is (more-or-less) common knowledge that our PT designs are generally quite conservative. We have all witnessed the fact that we get tendons cut on our projects (routinely)... we make a big fuss about it and yell at the contractor... the truth is that it almost never causes any heartburn... the slab works fine without that tendon.... WHY?!

The fact of the matter is that we have in the past used any combination of bottom rebar mats on our projects: #4 @18"; #4@24; #5@18; #5 @24, and so on... In many cases with PT design, rebar requirements for the most part are minimal in our PT slabs except for unusual conditions and spans that require "a bit more attention". So it is evident that our use of rebar at the bottom mat is generally VERY conservative, leading to a high steel tonnage in our slabs -which is part of the reason that we can weather the "tendon cuts" so well.

If we were at the other end of the spectrum where we max out the P/A at 4-500 psi with minimal bonded, then i think you would notice a snapped cable more...

All this to say - we should come up with a bottom mat configuration that we're confortable with that still gives us good use of materials and an efficient design...

Since the code ACI[18.12.4] will let us go to 8d or 60" for tendon spacing, and [18.9] spells out some minimum requirements for bonded rebar, we should consider relaxing our "strangle-hold" on the #5 @ 24"oc and ooch a little over toward say... #5 @ 36"oc?

Somebody...?

Link to Old CT Engineering Blog

Hey to all.

This blog is just a link to our old CTE blog. It was started by Rick Wyble and then got disconnected from use... i cannot administer it to change members etc. This link is for reference... the are some posts of interest:

http://ctengineering.blogspot.com/?zx=1dabcae7a7ebfd91