Designing resilient buildings
When earthquakes, typhoons or storm surges threaten the cities, towns and villages of the Philippines, local government buildings are often seen as the safest places to take shelter.
Schools, police stations, public markets, health centres, orphanages, and municipal halls are often also the epicentre of critical support operations during and following a catastrophe.
Located in the Pacific ‘Ring of Fire’, the Philippines has always been prone to earthquakes and other natural hazards. In recent decades, due to global warming, the country has seen changes in climate patterns, including stronger and deadlier typhoons.
And not all local government buildings have stood up to the force of such extremes.
When Super Typhoon Yolanda struck the provincial city of Tacloban on 8 November 2013, it ravaged everything in its path—even the police station crumbled. With wind speeds of more than 300 kilometres per hour and a 7-metre storm surge, Yolanda was, at the time, the most powerful storm on record to make landfall. In the Philippines alone, more than 6300 people died.
The ‘Build Back Better’ principle
The Philippines government subsequently doubled its disaster-preparedness efforts, and introduced the ‘Build Back Better’ principle, aiming to prevent the unending cycle of destruction and reconstruction. The idea is to build structures that are designed to be more resilient.
How to apply the ‘Build Back Better’ principle in practice, however, proved a challenge for local governments.
“The Philippines government had introduced very good national disaster risk reduction and climate adaptation policies,” says CSIRO Senior Principal Research Scientist Dr Xiaoming Wang, “but the policies were difficult to interpret in a practical sense and, in particular, difficult to implement at the local level.
“The national Build Back Better principle is really just the starting point. We needed to interpret it for local governments to work out what practical actions they can take. We also needed a way of quantifying the improvements because ‘better’ is a relative term.”
A risk-based approach to building design
When the Philippines government sought assistance from the Australian Government through its aid program, Dr Wang, an expert in climate adaptation and sustainable development, formed a small team to collaborate with the Department of Interior and Local Government to develop tangible steps that engineers could take to design new, more resilient buildings.
The team, which included CSIRO’s Dr Chi-Hsiang Wang and Yong Bing Khoo, with technical assistance provided by Professor Mark Stewart (University of Newcastle), used risk-based knowledge to develop structural design approaches for better resilience to extreme winds, earthquakes and floods.
The approaches are documented in detail in the handbook: Designing resilient structures: Mainstreaming disaster risk reduction and climate change adaptation in local design practices.
The handbook offers guidelines that apply the risk-minimising principle to achieve the desired level of resilience in structural design.
Assisted by a local project coordinator, Ms Connie Morga, the team engaged the Philippines government at all levels to analyse current standards and practices on building construction, design and maintenance, and to make sure that government engineers could understand and apply the guidelines.
The handbook was launched on 22 July in Manila, with engineers from all levels of government in attendance.
The resilience factor
An important element of the new design approach is the ‘resilience factor’. The handbook defines resilience factors to meet certain levels of structural performance required to withstand wind, seismic and flood hazards, in addition to meeting the National Structural Code of the Philippines (NSCP).
“The resilience factor creates a direct link with the national building code, or other existing design standards,” explains Dr Wang. “So there’s an extra design requirement for engineers to improve the resilience of their designed structures.”
Francisco Vargas Jr. is an engineer with Malabon local government unit, north of Manila: “This [resilience factor] is new to us. All factors incorporated in our design are based on NSCP. In our practice, first we have to comply with the code. It’s the prerogative and the choice of the designer to add or to apply additional load for his or her intuition. So now I can use the handbook to explain. So I can say that it’s not overdesigned. I can say, your structure is more resilient to this upcoming event or typhoon or earthquake.”
Justifying the investment
The investment by the Philippines government and by international donor agencies in the post-Yolanda reconstruction is significant. It is important to the government that they can justify the cost of increasing the resilience of buildings to natural disasters and climate change.
“To make something that is enforceable, you need something you can measure,” says Dr Wang. “So we also developed a process for estimating the costs and the benefits of designing for resilience.
This also provides an option for measuring the costs and benefits of implementing the Build Back Better policy in local government.”
Rolling out the guidelines
The roll out of the handbook to all local governments is the next step, and the government is seeking support to build capacity and capability on the ground to implement the guidelines, says Dr Wang.
Meanwhile, the national building code is under review and, in a move that is “pretty significant”, he adds, the Department of Public Works and Highways, which manages the code, has endorsed the handbook and will recommend to the review committee that they use it as a guide in revising the code.
The story may not end there.
The handbook was intended for local government buildings only, but could be used for residential buildings. The approach could also be extended to infrastructure such as roads and bridges.
Could it be used in other countries? “We’re considering that and engaging donor agencies at the moment”, says Dr Wang. “It could certainly be applied to other countries in East Asia. It may even be applicable in Australia.”
Read more about the research and guidelines to building resilient structures in the handbook.