UC research into high rise earthquake evacuees facing severely damaged stairways

A University of Canterbury engineer is researching the experiences of people who had to evacuate three of Christchurch’s tallest buildings with blocked exits or collapsed stairwells after the earthquake on February 22 last year.

The three high-rise buildings that lost their stairways left occupants with no way out of their buildings without outside intervention with the exception of the occupants that were able to abseil out of the lower levels of the 19-storey Forsyth Barr building.

``The exit systems in Forsyth Barr, the 17-storey Clarendon Tower and the 26-stroey Grand chancellor were severely compromised by debris in the open paths and exit ways, damaged walls and doors, and collapse of the stairways,’’ UC Associate Professor Charles Fleischmann.

``This made exiting very difficult for some and impossible for others. One of the many lessons learned from this event is that the design of stairways needs to be reconsidered by the regulators and the structural engineering fraternity.

``The final results of this research will show that even when confronted with horrific challenges, people came together to comfort one another and work together toward a common goal.

``The response to the survey shows that the occupants were under a great deal of stress and anxiety about their situation yet there were no reports of panic or inappropriate behaviour on the part of the occupants.

``Comments in the survey so far about the behaviour of others are universally positive. It is clear that there were widely varying responses of the occupants with some taking charge of their groups while others wished to simply wait for instructions,’ he said.

Associate Professor Fleischmann, from UC’s civil and natural engineering department, gained access to the Red Zone to investigate the damaged buildings months after the big quake.

He said lessons learned from this catastrophe were still in progress with engineers from all over the world flooding into Christchurch to learn from the disaster. Most of the efforts are focusingon the performance of the structures and the soil conditions.

``However my study focuses on the human behaviour and emotions of the occupants that were trapped above the ground floor in the high rise buildings that suffered stairway collapse. All three buildings remained standing after the earthquake and survived the period of intense aftershocks in the subsequent months.

``The Clarendon Tower and Grand Chancellor buildings have been demolished as they were considered structurally unstable and a threat to surrounding structures. I entered the Grand Chancellor and Forsyth Barr buildings after the quake to document the conditions that the occupants faced while attempting to evacuate.

``In addition to the site inspections people who were in those buildings have been asked to answer an online survey about their experiences including their actions and anxiety levels. I am still keen to hear from anyone else who was in the Grand Chancellor building on February 22 last year.’’

He said a large crane was brought in to evacuate the occupants from each level. For the Grand Chancellor and Clarendon Tower, the stairway suffered only partial collapse requiring occupants to cross over from one stairway to another and evacuate through cascading water and dust in the stairway.

Fortunately no one was in the Forsyth Barr stairwell when it collapsed. When the stairs failed it was complete failing from the 14th floor with both of the stairways collapsing in a pile at the bottom of the shaft. The failure of the stairway in this building was so complete that the occupants had to be rescued from a platform suspended from a crane or lowered on a rope from the lower floors to the roof of the carpark.

The damage to the Grand Chancellor Hotel building at 161 Cashel Street was so extensive that four city blocks were initially evacuated and not even rescue personnel were allowed into the area fearing complete collapse of the building, he said.

``Because the earthquake occurred in the middle of the day the total occupant load of the hotel was considered to be low,’’ Associate Professor Fleischmann said.