Quake Engineering:
Looking at the Turkish Earthquake Damage？
Despite the size of the devastating quake that ripped through Turkey, American structural engineers say there was something that might have alleviated the damage and saved lives. These images of the devastation in Turkey confirm what seismic engineers already know: that a powerful earthquake has an ally in a weak building. Jim Malley of Degenkolb Engineers, "This is the most common form. of multi-story building In Turkey. It's what we call a concrete frame." Structural engineer Jim Malley studied damaged buildings in Turkey in 1992 after a 6.8 (Richter Scale)quake left more than 600 dead. Jim Malley says, "These are very heavy buildings and it's not uncommon for them to collapse In earthquakes because of the extra mass. The risk of building collapse increases when the first floor is a shop and glass windows replace brick walls. Undoubtedly, there was a glass store front at this level, and all that came through for the structure, was concrete columns, and that made it much weaker, and as a result we got the collapse of that first story."
Malley says Turkey's concrete frame. buildings often lack reinforcing steel, use too little or use a smooth steel bar that fails to grip the concrete. "We use what's called deformed bars where there's little bumps on the steel, which helps to tie the reinforcing steel into the concrete, and smooth bars. it pulls out much more easily."
In California, where each big quake teaches engineers another way of coping, steel frames reduce the weight of new buildings, and strong joints keep them agile.
Janiele Maffei shows a San Francisco skyscraper under construction and says, "The building is designed to move and to sway. and the connections to stay together."
Structural engineer Jardele Maffei says the 1994 Northridge, California quake, revealed the weakness of rigid joints. Engineers found a simple solution, She demonstrates the point by way of the building under way, "See to the right of the connection. See the beam？ See how it looks like it's been tapered？ That's called a dog bone; you can see how it looks like a dog bone, how it's tapered. What that will do is it will take the stresses away from the connection, and concentrate them in that smaller section of the beam."
Cross bracing up the elevator shaft gives a building brute strength.
Janiele Maffei says, "What steel bracing does, is it connects the various floors, and keeps there from moving relative to each other in an earthquake."
Maffei says Turkish engineers do know how to build for earthquakes and building codes in Turkey are good, at least on paper. But somehow the system failed to produce earthquake resistant buildings
According to the article, what is the most common form. of multi-story building in Turkey？

A. Wooden structures.
B. Reinforced concrete single levels.
C. The concrete frame.
D. The dog bone frame.