Here's the link to the L.A. times article for those interested:
http://graphics.latimes.com/wilshire-grand-earthquakes/
The steel you are seeing at level 28 are 10 huge plate embeds that the gusset plates for BRBs will attach. These look like columns, but had to be set this way due to their massive size and tolerance constraints.
Below is an aerial shot where you can see those embeds being set and a close up f them on the ground before install.
image by
sljrinsd, on Flickr
image by
sljrinsd, on Flickr
Steel erection will continue North and West for several levels before South and East catch up. After that, the steel will go up floor by floor uniformly.