http://www.twdenthusiasts.com/wp-content/uploads/2014/07/Alexandria-Safezone-3.jpg

 

Yeah, if those are the attachment points for the braces, then definitely no cement anchors.

 

Yes, that photo raises more questions than it answers. Is that unistrut they're using for the foundation? How will the footings resist lateral load? How will the vertical members be connected to the footing?

Seems to me the purpose of those footings is to ensure that the fence will be level, and the lateral loads will be carried by other means.

 

I see an open trench with a line of receiving anchors. These are not for anchoring the braces but for the columns of the wall. The columns might be field-welded onto the square base plate (or that plate is temporary and will be removed when the columns are ready to be bolted with the four bolts underneath). (Actually the columns are not behaving like a typical column because the predominant force is not axial but flexural, as the wall mainly resists lateral loading, ie wind and pushing by walkers). That trench will surely be filled with concrete, perhaps with nominal reinforcement, to act as a strip footing to provide the needed horizontal support from ground pressure.

For the braces, note the two grey anchor points (steel angle) at the upper right corner of the pic. Clearly, these are to receive the braces. In one of the pic in the link below, I can see that anchor point has a 'square-ish' concrete footing. And, in the pic above, you can see some soil disturbance around those 2 steel anchors. So I say that the grey steel angle anchor is not simply driven into the ground but a hole was dug to receive the steel angle (which perhaps has an anchor plate at the end to anchor itself in the concrete footing) and then filled with concrete before covering with top soil.

Below is a link with some nice pictures showing the construction of the wall. Each wall section is prefab and lifted onto its position.

http://www.11alive.com/story/news/local/2014/07/16/walking-dead/12746931/

 

actually diesels would be the only thing still running. All of the gasoline will have turned to a gel by now, but diesel engines can run on all kindsa crap.

 

There are all kind of fuel polishes available on the market to revive old fuel. Should be little problem.

 

So it behaves like a cantilevered beam rotated 90 degrees? The connections at the wall are welded. The brace anchors have two different type of connections, a shackle connection and just plain bolted. [MENTION=23322]westwingnut[/MENTION]
I wonder if the unistruts are made of a high tensile steel. Sometypes of high tensile steel have yield strengths almost double of A36. I also have a question about beams used in construction, does the steel used require certs and material marking?
I also went back and looked at my textbooks, all of your statements about dislocations were correct. When I studied this we spent one class discussing this and because this happens after yield it wasnt important in determining failure.

 

The t.v. reporter said the wall would take ~3 weeks more to build, when there were two sections up behind her. Even figuring that there were things placed in the ground before building the wall, it probably didn't take an experienced crew more than a couple of months to build overall. 6-9 months for a crew of noobs sounds doable now.

 

yes, but how many gallons can the stuff from auto zone and such treat? Each store only carries a finite amount of additive.

Not to mention once the gasoline is completely gelled, there is no fixing it. IT essentially becomes gel fuel like in sterno cans.

 

I think you are right, the vertical members had to be welded to the those plates. Then concrete was poured in pace to provide lateral support.

I still think the vertical beams are the weak points, whether they are cantilevered or are pinned at both ends. I suppose the flexural capacity depends on whether the ribs on the cladding are running vertically or horizontally.

 

Even 2 months or less is doable for the first wall, as Bruce said there's already been one expansion. And in a ZA, you'd have much motivation to move fast. Work overtime....weekends...

 

It should not behave like a vertical cantilever. At its base, the concrete footing offers little rotational support. At its top, it is supported by a brace.

I like to see a close-up detail of how a brace is connected to the top of the beam/column.

 

I'm bumping an old thread to post a story about the deaths of 6 people caused by substandard construction near UC Berkeley. There were 13 people on a 4th-floor balcony when it gave way. The balcony ended upside down on top of the balcony below it, but all the people fell down to the street.

I've had my version of fun commenting on those braces, but they are there for a reason.

http://www.sfgate.com/bayarea/article/Five-dead-8-hurt-in-Berkeley-balcony-collapse-6329902.php

 

Told everyone that a truck ramming the wall wouldnt knock it down.

 

Well, not a truck that veered off its course at the last second due to the driver passing away.

 

I went back and watched this scene again. The truck hasnt lost much of its momentum when it hits the wall. The impact is almost perpendicular to the wall. Also the impact is at the weakest point in the wall as far as the bracing is concerned. The supports are attached to the church, not anchored in the ground. The veering of the truck has little to do with the end result of the wall standing. The wall has withstood a massive impact by a massive vehicle which a lot of people thought would knock it down, but it still standing.

 

I went back and watched this scene again. The truck hasnt lost much of its momentum when it hits the wall. The impact is almost perpendicular to the wall. Also the impact is at the weakest point in the wall as far as the bracing is concerned. The supports are attached to the church, not anchored in the ground. The veering of the truck has little to do with the end result of the wall standing. The wall has withstood a massive impact by a massive vehicle which a lot of people thought would knock it down, but it still standing.

 

Well, the camera jumps from one vantage point to another during the shot, so we can't really say how much momentum it lost. From the position the walker was found, its likely his foot had slipped of the break after he was shot. Plus it lost momentum from crashing through the bell tower. And veering has a lot to do with losing momentum. If the momentum of an object is directed ina straight line, and that line suddenly changes, momentum is lost to the change of direction.