Crane Question

[pontiacgp]

They are putting up a highrise condo building the crane they are using has an arm circled in red that is not in place. It's obvious it's not in place but they are using the crane. There are other buildings going up and all the cranes have that arm in place and locked. Does anyone know why thiey would be using the crane without the arm locked in place?

 

[BuickOldsPontiac]

As a former engineer (that worked with bridges), it looks like it could be designed as two separate trusses. I wouldn't be completely surprised if the connection below the gap is a hinge and the stays connected to the top of the outer truss are designed to carry the load in the vertical axis.

Or it could be a lawsuit waiting to happen too.

 

[TURNA]

Looks like a Union worker put it together!!!

 

[pontiacgp]

As a former engineer (that worked with bridges), it looks like it could be designed as two separate trusses. I wouldn't be completely surprised if the connection below the gap is a hinge and the stays connected to the top of the outer truss are designed to carry the load in the vertical axis.

Or it could be a lawsuit waiting to happen too.

there is another crane, same company, a few blocks away and they have that arm connected. The operator of the crane can see that the arm is up so it must not be needed but I don't see why they don't connect it unless there is a reason.

 

[ssn696]

The weight of the truss arm plus the suspended load goes mostly through the cable stays toward the top of the tower. The load on the truss itself goes primarily through the truss back towards the cab area. I might be worried if high winds act on the truss from below while it has no load on it. That said, a call to the crane company might save you and your neighbors from being in the news.

 

[pontiacgp]

I was out on my 2.5 mile walk and took a good look at the other crane, I was mistaken and the arm is not attached on that one either. The arm is slightly pointing down and sitting just below where it would connect so looking at it from a different angle I could see that it was not connected. I guess on the configuation they have they do not connect it.

 

[pontiacgp]

I fianlly had a chat with one of the guys at the site and he said a few people have asked him about that arm that isn't connected. He explained that arm is used when another section of the boom is added. The tripod that holds the cable to angle it down to the bream is then futher down the beam making it necessary to connect that arm. It's not connected with a short boom to allow the boom to flex at the point where the tripod is.