Vancouver House (1400 Howe St) | 151.5m | 52Fl | Completed

[vanman]

^ I think the complexity of the Vancouver House site is fairly obvious. It's irregularly shaped, on a significant slope, and has to contend with a bridge viaduct. Telus Sky's site, although tight, is flat and rectangular.

[Design-mind]

^^^Not to mention that Vancouver House will have to contend with seismic activity on a fairly frequent basis.

[jollyburger]

Crane went into Telus Sky in Nov 2015, first crane for Vancouver House in February 2016.

[Dimswitch]

The House today Feb 7th

[dleung]

The top heavy design also required a lot more concrete to be poured into the foundations - some parts of it looked like it was for heavy civil works like a dam.

[mcminsen]

Feb.11 '17, my pics

[Marshal]

Well, you can certainly see the 'extra' rebar going up the west side to resist the cantilever. The engineering drawings I saw were different: they showed what I thought was an interesting post-tensioned cable system to do this structural work. It was just a brief look and I must have mistaken something. A little disappointing to see the traditional solution. Oh well, it will still be a pretty cool tower to watch go up.

[Flynn86]

This site is moving fast.

[officedweller]

Probably more reassuring with them having taken the traditional approach.

[Marshal]

Originally Posted by officedweller

Probably more reassuring with them having taken the traditional approach.

Why? Our new cable bridges are fine. It's not rocket science and engineers are actually pretty good at this stuff.

[officedweller]

Originally Posted by Marshal

Why? Our new cable bridges are fine. It's not rocket science and engineers are actually pretty good at this stuff.

In case of water leakage into the conduits holding the cables
- it would be a nightmare to replace the cables.

Pacific Point (admittedly one of the first in the city to use post-tensioned cables) had leaks and had to replace cables in their floors.

In this case, it would be vertical stability, not floor suspension, which could run a much higher risk of failure if there were a problem in future.

[christmas]

Thanks for the update!
They will bury the 2 utility poles right?
Cuz this looks third worldly..

Picture courtesy of McMinsen

[SFUVancouver]

Originally Posted by christmas

Thanks for the update!
They will bury the 2 utility poles right?
Cuz this looks third worldly..


Picture courtesy of McMinsen

Indistinguishable!


Source

McMinsen, I appreciate the thorough update. Thanks!

[Marshal]

Originally Posted by officedweller

In case of water leakage into the conduits holding the cables
- it would be a nightmare to replace the cables.

Pacific Point (admittedly one of the first in the city to use post-tensioned cables) had leaks and had to replace cables in their floors.

In this case, it would be vertical stability, not floor suspension, which could run a much higher risk of failure if there were a problem in future.

You make it sound like this is some new, almost experimental, technology. We have been using post-tensioned steel for decades - in buildings, but more often on the Civil side: overpasses, stadiums . . . Post-tensioned steel is old hat and as safe as anything. As for water penetration, that isn't possible. The steel is inside a sheath, and the bolt/washer systems at the open ends provide complete closure. After-all, they are resisting very large forces from the tension in the cable. We even use this system outdoors. The cables on the Port Mann are the same technology, just outside carrying the deck load. They are not in a sheath, but are wrapped to achieve the same water resistance. There must have been much larger problems with the structure at Pacific Point.

Also, the direction of the forces, vertical, horizontal or whatever, has no bearing on risk of failure. The load is the only variable in that category. A cable under high tension does not 'know' what direction it is oriented to.

In Vancouver House, the steel we are talking about functions to resist the turning load caused by the building's overall cantilevered shape. It is separate from the floor system and the normal stuffings used to resist lateral loads.

[officedweller]

Originally Posted by Marshal

You make it sound like this is some new, almost experimental, technology. We have been using post-tensioned steel for decades - in buildings, but more often on the Civil side: overpasses, stadiums . . . Post-tensioned steel is old hat and as safe as anything. As for water penetration, that isn't possible. The steel is inside a sheath, and the bolt/washer systems at the open ends provide complete closure. After-all, they are resisting very large forces from the tension in the cable. We even use this system outdoors. The cables on the Port Mann are the same technology, just outside carrying the deck load. They are not in a sheath, but are wrapped to achieve the same water resistance. There must have been much larger problems with the structure at Pacific Point.

Also, the direction of the forces, vertical, horizontal or whatever, has no bearing on risk of failure. The load is the only variable in that category. A cable under high tension does not 'know' what direction it is oriented to.

In Vancouver House, the steel we are talking about functions to resist the turning load caused by the building's overall cantilevered shape. It is separate from the floor system and the normal stuffings used to resist lateral loads.

Yeah, I know that post-tensioned cables are used everywhere nowadays.

They must have new systems for water resistance than those early ones, but there were leaks at Pacific Point that resulted in massive special assessments.
I assume that it depends on the quality of the workmanship, too.

This was in 2010 for a 2001 tower:
http://www.treehugger.com/sustainable-pr...emolished-its-all-of-nine-years-old.html


When I said "risk of failure" I meant building failure (if the cables had already failed), not cable failure in the first instance because of orientation (i.e. if the cables failed, the building could fall over because of the cantilever, rather than just having a sagging floor).

[Marshal]

Thanks for the link. Now I know where your statements were coming from.

As you already seem to know, that system is not used very often: it is costly (relative), difficult to implement (I would want small scale post-tensioning to be done in the controlled environment of a factory), produces a result that is prone to noise transmission and flexing movement under live loads (there is always a percentage of structure that simply functions to remove experiencable building movement/vibration).

That Seattle project displays astonishing incompetence. That scale was not even on my mind because it is rarely done here. The system on Vancouver House that I was discussing would have been post-tensioned cables running 10 - 20 stories in length, inside their own concrete, up the west side of the whole structure.

As a side note to the Seattle failure, architects/engineers can be implicated for specifying systems that do not meet reasonable plausible constructability. The contractor is not necessarily expected to understand the technical risks of such construction. They can legally shed some of that responsibility onto the design team.

[officedweller]

Just realized that I can see one of the cranes from my place.

Pic by me today:

[mcminsen]

The main tower floorplates have risen up to the same level at the Howe Street ramp and the rebar extends several floors above that. I'm really looking forward to seeing the tower start to take shape now. By summer it will be amazing to see. Maybe it will top out in about a year?




March 4 '17, my pics

[mcminsen]

March 4 '17, my pics

[domusile]

Correct me if I am wrong but a standard tower floor plate goes up at a rate of ~7 days. Curious what the average will be for Vancouver House given that each floor plate is unique.