What happened: Two hundred firefighters from 10 fire stations (estimated) responded to reports of a structure fire at the iconic Plasco building Thursday morning in Tehran, Iran. The 17-story Plasco building was constructed in the 1960s and was once Tehran’s tallest structure. It was designed as a multipurpose structure providing retail, commercial and residential space.
Initial reports state that the fire began on the ninth floor and spread rapidly. Firefighters were confronted initially with significant life safety challenges in evacuating the occupants while battling the rapidly expanding fire.
After several hours of firefighting and rescue efforts, the north wall of the structure was compromised and the upper floors collapsed. This appears to have been a pancake collapse and the ensuing collapse zone was relatively contained to the immediate building footprint with minimal to moderate damage to adjacent areas.
Tragically, an estimated 30 to 45 firefighters were in the structure at the time of the collapse with an unknown number of civilians. According to some news reports, occupants were breaching the established barricades and making their way back into the structure during the blaze to retrieve possessions. This makes accurate accountability of potential victims unknown at this time.
Currently, rescue efforts are underway to access potentially trapped victims and confirmations through text messages have been received from firefighters who are reportedly trapped in the basement.
Actions taken by firefighters
Initial crews reportedly established barricades and evacuated surrounding areas while attacking the fire with transitional approaches and conducting interior search and rescue operations. Aerial operations were initiated and water supply appeared to be deployed as expected.
The initially involved ninth floor fire quickly expanded to the upper floors resulting in a fully involved structure fire from the ninth floor to the roof. Al Jazeera reports imply there were significant safety concerns with the Plasco building:
“We had repeatedly warned the building managers about the lack of safety of the building,” fire brigade spokesman Jalal Malekias said, adding that it lacked fire extinguishers.
“Even in the stairwells, a lot of clothing is stored and this is against safety standards. The managers didn’t pay attention to the warnings,” he said.
Risk factors for structural collapse
Firefighters are trained to be dedicated students of building construction and have a heightened sense of awareness and knowledge about the impact that fire has on structural integrity. Here are three questions about the risk factors for structural collapse.
1. Was building design compromised?
The Plasco building had a steel frame with lightweight steel integration. Due to the mixed occupancy classification, it is possible that the loads applied to the upper floors may have been in excess of the building’s design. The upper floors reportedly housed much of the commercial or manufacturing occupancies. Excessive loads may cause flooring systems to be compromised prematurely when weakened by fire involvement.
2. Was the fire load excessive?
Additionally, the fire load caused by cluttered stairwells and common areas could have contributed to rapid fire growth and limited access or deployment for fire crews. All of these hazards were known, to some degree, by the firefighters prior to the event through pre-planning and previous events. This information should play a serious role in tactical decision making. However, saving lives always drives us to take necessary risks because it is our job. The challenge is always calculating those risks and reducing them as much as possible while still attempting to save lives and property.
3. Was the building in compliance with codes?
As the event unfolded and the time of fire exposure increased, the potential for collapse increased exponentially. In the United States, we have the luxury of stringent building codes and requirements for fire-rated materials. We have regulatory processes in place that help ensure compliance. This affords us the luxury of time and reasonable predictability.
It is unclear at this time what measures were in place regarding Plasco building fire resistance and code compliance. The Iranian government has launched a preliminary investigation into analyzing this tragic event and all of the contributing factors associated with the outcome.
Assessing potential for collapse
Constant evaluation of the building and the fire conditions are paramount in these incidents. Knowing the building’s construction and applying predictive assumptions to the structure’s reaction to fire is imperative.
This is a list of key things to look for when weighing the potential for collapse against the necessity for interior operations. When any of the following conditions are present, serious consideration must be given to defensive operations and withdrawal from the structure:
- Structural inadequacy, poor construction, illegal or non-engineered renovations.
- Fire size and location, and conditions on arrival.
- Age of building.
- Previous fire.
- Fire load to structural members.
- Backdraft or explosions.
- Engineered lumber, truss joists, nail plates.
- Load increase as a result of water load.
- Cutting structural members during venting operations.
- Cracks or bulges in walls.
- Water or smoke that pushes through what appears to be a solid masonry wall.
- Unusual noises coming from building or dwelling.
- Truck operations notice soft or spongy footing.
- Weather extremes.
Learn more about building collapse
Be aware of the signs of potential collapse and be aggressive about pulling personnel out of the building and the collapse zone to re-evaluate. Establish perimeters that are appropriate collapse zones. We cannot save lives when the rescuers become the victims.
