Climate & Environment

Joint Research Initiative

Hong Kong

Earthquake and Typhoon Vulnerability Analyses of Buildings in Asia-Pacific

As an insurer with a strong presence in Asia, AXA is looking to integrate a vulnerability module (including water level and wind speed) in its internal natural catastrophes models in order to be able to accurately measure hazard intensity and assess economic losses to insured buildings, to build fragility curves and be able to better price risk. To do this, and considering the current lack of research available for Hong-Kong and the Philippines, two key Asian countries for the AXA Group, a joint research project was developed between a team of academics led by Professor Ray Kai Leung SU from University of Hong-Kong (UHK) and two AXA Group Risk Management (GRM) experts, Mathis Joffrain and Amanda Johan, respectively based in Paris and Hong-Kong.
Earthquakes and typhoons represent a major risk in Asia, especially in densely populated coastal cities such as Hong Kong, Shanghai and Manilla. Many existing structures in those cities are not designed to withstand major earthquake or super-typhoon loads. Those structures may therefore suffer different degrees of damage, depending on the intensity of earthquake or typhoon.

Earthquake risk

Buildings with irregular structural form or significant vertical discontinuities, such as transfer plate structures, are particularly prone to earthquake damages. The failure of non-seismically designed shear walls can lead to partial or total collapse of building, even for low level earthquakes.

These structures become particularly common in low-to-moderate seismicity metropolitan cities around the world, including Hong Kong, Shanghai, and Singapore.

Displacement of building structure has been increasingly recognized as a crucial parameter in the seismic performance evaluation. Seismic fragility analyses based on displacement are recent advances for assessing building structures subject to earthquake loads. However, this has rarely been conducted for buildings with transfer structures or buildings with special structural forms.

Typhoon risk

The challenge of designing buildings resilient to typhoon impact is to assess the wind resistance of the building and the corresponding damage susceptibility. The dynamic response of a building in a given wind environment is governed by several factors including shape, stiffness, mass and damping. Whilst the effect of shape can be assessed by wind tunnel testing with reasonable accuracy, the limited measurements available show significant variability.

Due to complexity of probabilistic wind pressure distribution, a complete set of analytical tools, which would be likely to augment or replace laboratory testing to determine the loading capability of a site-specific wind, is currently unavailable. Significant research is needed before design engineers can accurately assess the wind-induced response of buildings to the effects of typhoon.

Fragility analysis project

Fragility analyses calculate the degree of damage inflicted to a building in respect to load intensity and are highly dependent of local building practices.

Fragility analyses for earthquake or typhoon risk in Asia are extremely scarce (except in Japan and Taiwan). They need to be building specific and therefore require intensive computing and high skills in building engineering. This is the purpose of the joint research project jointly led by the University of Hong-Kong and AXA Group Risk Management (GRM).

This academia-business collaboration will enable to develop a set of fragility analyses for the following buildings in Asia-Pacific:

1. An exhibition centre in Hong Kong (for both earthquake and typhoon risks)

2. A 30-story residential building in Shanghai, Hong Kong or Perth (for earthquake risk only)

3. A commercial building in the Philippines (for typhoon risk only)

These buildings have been carefully selected by AXA GRM for their strong similarities with insured buildings in Asia. After the fragility analyses are performed by the academic team, the economic costs. will then be derived by AXA team based on the predicted level of building destruction.

This project will then enable to connect specialists from civil engineering field, who can translate any natural peril intensity into building damage, with specialists from insurance field, who can translate any building damage into monetary costs.

AXA has also a strong interest in building resilient cities. It is therefore expected that this joint research initiative will foster research underlying the implementation of local building codes, on top of fostering academic publication of fragility curves that are currently not available.

February, 2021

Su
KAI LEUNG RAY

Institution

The University of Hong Kong

Country

Hong Kong

Nationality

Chinese