Grand Chancellor Christchurch

[hokie66]

It looks they are going to try to stabilise this building, which earlier was expected to collapse.

http://www.hawkesbaytoday.co.nz/loc...arthquake-stabilisation-work-starts-/3942564/

 

[JAE]

It says the building tilted sideways for a full metre? For a 26 story building what does that work out to in L/deflection ratio?

Sounds like a set of corner columns failed and they are jacketing them with steel and concrete infill.

 

[hokie66]

Based on the first reports, I had thought that liquefaction has caused the piles under the building to shift laterally, but it now sounds like structural failure at the ground floor level. The columns up in the building may have failed subsequent to the tilting.

 

[BAretired]

The buildings in Christchurch are a concern, but, at the moment, not the major concern in New Zealand and it is difficult to focus on buildings when human lives are still in jeopardy.

BA

 

[hokie66]

I certainly didn't mean to put the buildings before the lives, but the status of this building at the moment is hampering the recovery efforts in a large part of the central city. Stabilising this thing would be a big contribution by our engineering colleagues.

 

[rowingengineer]

From the little I have heard the forces that were transferred to the building in the "poor" soils were twice what they could have at best been designed to withstand. I think all structures will need an assessment in due course. I imagine that a code revision sto remove this new challenge will be required. The human impact is turning to discomfort rather than death, since the chance of been found alive after this point are slim, they will need all the building that are standing to house the people out of accommodation.

ANY FOOL CAN DESIGN A STRUCTURE. IT TAKES AN ENGINEER TO DESIGN A CONNECTION.”

 

[keenaseng]

If the piles are in reasonable stiff soils, is it possible the EQ forces could have sheared the building off the piles causing the building to tilt?

Even poor soils could provide sufficient restraint to the piles when subjected to rapid lateral movement from EQ

 

[apsix]

Refer;

http://www.ecan.govt.nz/publications/General/solid-facts-christchurch-liquefaction.pdf

Reasonably stiff soil is not a description for Christchurch's soil.

 

[BAretired]

hokie, you were correct about liquefaction as shown in one of the photos shown in this link:

http://www.theatlantic.com/infocus/2011/02/earthquake-in-new-zealand/100013/

BA

 

[hokie66]

Yes, the liquefaction which occurred there was amazing to me. I am not well versed in seismic behaviour, but there were mini volcanoes of mud all over the place. Still not sure if liquefaction was a major contributor in the leaning of the 26 storey building, as other structural issues have been identified.

 

[a2mfk]

Some really sad pictures, but some great detailed pics for structural engineering educatin...

Photo 10 is a great example of inherent redundancies in wood-framed roofs, the diaphragm must be in tension which is amazing as it appears interrupted by that dormer/gable feature...

And Photo 44 a textbook "soft" first story shear wall failure, though the second story had almost no shear walls either.

 

[Gillespie]

Regarding all these pictures and the overall damage of this earthquake to our beloved kiwi friends.
First this should be a wake up call to California Building Owners.
This will be our state. Liquefaction, soft story buildings, and old brick veneered buildings will be the pictures from our seismic event.

The other is the relationship of weight and building stiffness. Either one is critical, but together they are a recipe for failure.