Preventing Pancake Collapses: Lessons from Earthquake-Resistant Traditional Construction for Modern Buildings of Reinforced Concrete

It seems counter-intuitive to assert that simple, unsophisticated, non-engineered, timber and masonry structures might be safer in large earthquakes than new structures of reinforced concrete, but such has proven to be the case in a number of recent earthquakes, including the Izmit and Düzce earthquakes in Turkey of 1999, the Bhuj earthquake in India of 2001, and the Kashmir earthquake in Pakistan of 2005. The question of what lessons can be derived from this information in present times is even less obvious, as these buildings now seem so archaic as to be more easily associated with the medieval rather than modern world. However, in many different regions of the world, the earthquake record with contemporary structures of reinforced concrete frequently has been abysmal. Such buildings are even respons ible for what has come to be called a “pancake” collapse – where heavy and unyielding floors collapse one atop the other with people trapped and crushed in between. In fact, before the advent of the strong materials of reinforced concrete and steel, many societies had developed an approach to seismic resistance that is only slowly being re-learned in the present: that it is wiser to build flexible structures than to attempt to build ones that resist earthquakes only by their strength. This paper will explore the specifics of what can be learned from these historical construction practices, by describing the author’s concept for “Armature Crosswalls,” a concept based on Turkish and Kashmiri traditional construction adapted for reinforced concrete infill-wall construction. The value of this approach for Heritage Figure 1: Detail of traditional himis construction in Turkey in mid-20 century house in Gölcük.