A number of studies have been done on that around the world, and the National Research Council of Canada (NRCC) is doing others right now. There was a demonstration fire, and various firefighters' associations were on site. They placed sensors at various depths in the wood, and the fire got up to about 1300 degrees Celsius. Because there were no sprinklers used in the test, everything burned up within about 20 minutes. At one centimetre into the beam, the temperature had only risen one degree Celsius. The beam is therefore oversized to ensure that the burning part protects the load-bearing part. Calculations show that if the building had been made of steel, the beams would have buckled and the building would have collapsed.
So don't confuse the new wood use technologies—they are building up to 23 stories nowadays—with light-frame construction like 2 x 6 or 2 x 4 houses, for example. That's something else entirely.