Rebuilding the Indonesian island of Sulawesi after the earthquake

The death toll from the devastating Sulawesi earthquake and subsequent tsunami continues to, tragically, rise.

Most of the deaths have occurred in the small city of Palu, about 1500 kilometres northeast of Jakarta, where more than 3000 homes and buildings were also destroyed, including the local shopping mall and the eight-storey Roa Roa Hotel. Roads and bridges were also washed away when six-metre high tsunami waves smashed into the beachfront.

In the Palu neighbourhood of Balaroa alone, more than 1700 houses were swallowed up when the earthquake caused soil to liquefy.

When the human scars of this devastating and tragic natural disaster have begun to heal, attention will need to focus on rebuilding the community.

Building resilience

Designing critical infrastructure to a more resilient standard than what building codes mandate should be of utmost importance when rebuilding environments affected by natural disaster – such as the Indonesian island of Sulawesi.

As climate change increases the severity of natural disasters at scales not considered in the initial design of buildings – some of which could be decades old - everything from the family home to office buildings and hotels should be monitored to ensure their structural safety and reliability under extreme events.

While the clean-up and rebuilding effort in Indonesia is going to take several years, questions will be asked of those in the affected communities as to whether the homes and buildings they occupied were built to withstand severe seismic and other disaster events.

Going beyond the code

Most of the structural problems surrounding buildings in Indonesia relate to minimum reference to standards/codes – despite the country having a Seismic Resistance Design Standard for Buildings.

The recent Sulawesi earthquake, which has claimed almost 2000 lives and wiped out communities across the island, shows that many buildings were not able to withstand a natural disaster of this magnitude.

Any structure should be sufficiently strong and ductile to absorb the energy caused by earthquakes and survive the vibrations with acceptable damage. Sometimes, it is necessary to equip structures with special technology, such as base isolation and structural vibration control technologies, to minimise extreme forces and deformations caused by earthquakes. Cost barriers, however, could prevent this technology from rolling out across all buildings.

Sadly, the number of human casualties and associated economic loss due to these earthquakes in Indonesia is significant, mostly due to the damage and collapse of buildings and infrastructure that are not properly engineered.

The recent Sulawesi earthquake, which has claimed almost 2000 lives and wiped out communities across the island, shows that many buildings were not able to withstand a natural disaster of this magnitude.

‘Soft-storey’ was the most common failure. The term ‘soft-storey’ refers to one level of a multi-storey building that is significantly weaker in lateral load resistance than the levels above or below it. These types of buildings may also exhibit larger than usual windows, doors or other openings that reduce stability.

The lack of consideration for the placement of openings and non-structural elements may cause ‘soft-storey’ which then leads to the progressive collapse of the entire structure, which occurred with the Roa Roa Hotel.

Some damage has occurred on building walls that were often left unconnected to beams and supporting columns, meaning that no anchorage was provided from these walls to columns and ring beams, which ultimately led to their collapse.

Australian solution to rebuild disaster-affected communities

So how can Indonesia and the Sulawesi community rebuild itself after this tragedy and, most importantly, better prepare for future acts of nature?

Firstly, the buildings and structures should be rebuilt using innovative cost-effective and disaster-resilient prefabricated components with proven exceptional specifications in terms of resistance and recovery capacity, construction costs, time, and efficiency.

One example includes the prefabricated hybrid structural components developed by Monash University researchers. These consist of ultra-high strength (UHS) steel tubes welded to the corners of mild-steel plates.

The interaction between mild-steel plates and high strength corner tubes in these sections results in a significant increase in energy absorption capacity, compared to what is expected from the high strength steel material alone, making them a suitable choice for regions prone to extreme events.

These innovative components can be made offshore, and be fully bolted to the beams with minimal work on-site through the patented modular connections. This ensures efficient assembly/disassembly and reusability in the aftermath of extreme events.

Secondly, proper detailing and structural configuration must be considered to avoid ‘soft-storey’ and other defects. Indeed, designing resilient structural assemblies in accordance to the latest codes of practice can satisfy this requirement.

and most importantly, educational avenues to improve the skills of construction engineers have to be explored so as to update their knowledge with the latest construction technology and trends such as Design for Manufacture and Assembly (DfMA) technology, the new era for digitalisation of construction that the modern construction industry pays significant attention to.

To mitigate the consequences of these extreme events, combining efforts from governments, decision-makers, and various local as well as international institutions are also required. We should not forget that earthquakes and tsunamis are natural disasters. We live with these kinds of disasters and cannot remove them from our life. However, by using engineering-based solutions we can control and mitigate their consequences.