Enhanced version of seismic simulation software "wallstat" released with calculation time reduced to 1/10

The free software "wallstat" can perform seismic simulation without using a large-scale shaking table. It was developed by Associate Professor Takafumi Nakagawa of the Kyoto University Research Institute for Sustainable Humanosphere (RISH) and is used by many contractors. Associate Professor Nakagawa has recently released an enhanced version that shortens the time required for one simulation, which used to take approximately 16 minutes, to approximately 1 minute. A simplified version (wallstat S) that can be used without detailed building data has also been released. Associate Professor Nakagawa said, "This enhancement ensures easier practical implementation. It is my hope that it will be widely used by researchers and structural designers as well as designers of construction shops and house makers , and will be used for verification of seismic performance, customer presentations, and awareness of disaster prevention".

Wallstat models a building three-dimensionally on a personal computer (PC), provides various seismic motions such as past earthquakes and assumed maximum earthquakes, and facilitates determination of the seismic performance of a wooden house via video. It has been downloaded more than 50,000 times by home designers. The design data of the building are entered, and for example, when an earthquake of the same level as the Great Hanshin-Awaji Earthquake occurs, the user can observe which walls and beams in the building undergo damage, destruction or even collapse. However, since it takes 20-30 minutes for each simulation on a general PC, observing the results of added seismic retrofitting while consulting with the customer is time consuming.

In this version upgrade, the stress calculation algorithm was reviewed; thus, the accuracy could be maintained even if the number of divisions per second was reduced from 100,000 to 10,000, reducing the calculation time to approximately 1/10. In addition, wooden houses are composed of many building materials, such as load-bearing walls and reinforced hardware. The strength of each building material is confirmed by fracture experiments and numerical values, such as wall magnification, are used for designing. However, data from original destruction experiments are rarely used.

Since wallstat models the deformation and strength of individual building materials in detail, it requires data on building material destruction experiments that are not typically available. Users had to contact the building material manufacturer to obtain individual experimental data up to now, which was a hassle. To eliminate this problem, the Seismic Performance Visualization Association (http://support.wallstat.jp) began developing a building material database for wallstat 2 years ago in cooperation with building material manufacturers. To date, information on more than 100 seismic components from 20 companies can be downloaded and incorporated into wallstat.

Furthermore, a simplified version of wallstat S has been released. In the simplified version, it is possible to easily perform a simulation based on the structural drawing of only the walls and columns, without layout/dimensions or ceiling finish input. Therefore, seismic performance can be observed even in older houses that do not have a structural plan. This can be downloaded from the RISH website (http://www.rish.kyoto-u.ac.jp/~nakagawa). Associate Professor Nakagawa said, "Wallstat S can be used for floor plans and more; hence, I definitely want the general public to use it".