The technology that will make strengthening buildings economically profitable even in the periphery
The technology that will make strengthening buildings economically profitable even in the periphery
A successful experiment by the Ministry of Construction to strengthen buildings using shock absorbers instead of concrete will allow the Ministry to double strengthen buildings in high-risk areas.
Amitai Gazit, Calcalist Published: 21.11.19, 08:24
Saving of 50% in the cost of a project to strengthen buildings against earthquakes using an advanced method implemented by the Ministry of Construction in the Amidar buildings in Eilat, shortening the schedules by at least a third, and works that were hardly noticed by the building's residents. These conclusions seal a report that was submitted to the Ministry of Construction by Yaron Ofir Engineers and reached Calcalist.
The report summarizes findings from an initial project that was used as a pilot to examine the effectiveness of an advanced method for strengthening buildings against earthquakes. Following the findings, the Ministry of Construction decided to make it the default choice in neighborhood rehabilitation projects, its use has been expanded and is already being implemented in seven buildings in Eilat, in a building in Hazor HaGalilit, and in an inspection office The application of the method in another project in Kiryat Shmona.
Residential buildings in Eilat. The upgrade works do not need to place scaffolding around the building and therefore do not disturb the tenants (Photo: Meir Ohion)
In the 15 years that have passed since TMA 38, the national program for strengthening buildings against earthquakes, came into force, there has been no change in the engineering methods used to strengthen the buildings. The classic method that has always been used is to wrap the building in concrete from the ceiling to the foundations, with the aim of stiffening it.
In the new method, means are used that are known in the professional parlance as energy wasters: similar to shock absorbers in a bicycle or car, these components absorb the energy generated in an earthquake and reduce the forces that the building absorbs.
The works are carried out in the foundations of the building only
In the pilot project carried out by the construction ministry through the Amidar company in the Ofir neighborhood in Eilat, three four-story railway buildings were upgraded, including a pillared floor. Each of the buildings has 30 apartments. The energy-dissipating components chosen were steel diagonals attached to the foundations and columns. In addition, the work included treatment of the existing foundations, replacement of old infrastructure, and repair of wear and tear. After the completion of the project, the authors of the report found that the cost of upgrading the building was only about NIS 30,000 per apartment on average - 50% lower than the cost of a conventional upgrade.
The general cost of the project included aspects not related to strengthening against earthquakes, such as finishing and development works, and reached NIS 100,000 per apartment. The authors of the report conclude that the conventional solution for the railway building in question in Eilat would have cost NIS 5.9 million, but in practice it only cost NIS 2.8 million - 48% less. In addition, the execution time was 30% shorter than leg projects and was completed within 9 months in the first building, And due to the accumulated experience, the upgrade of the next building was completed within 6 months - and this compared to the year to year and a half that a strengthening project of the Ministry of Construction usually takes.
In addition to this, the report states that the project does not disturb the tenants, because the work is carried out only on the floor of the columns and foundations, and there is no touching of the inside of the apartments. This, while conventional projects require friction with the tenants, who are sometimes required to leave their apartments, and in any case always suffer from living in a building covered in scaffolding .
Following the success of the pilot, the Ministry of Construction decided to expand the project to four more buildings in Eilat, to another project in Hazor HaGalilit, and the possibility of applying the method in Kiryat Shmona is also being considered.
The projects of the Ministry of Construction in the periphery are not in the format of TAMA 38, and do not include apartment additions and MMD. However, the new strengthening method can also be used in TAMA 38 projects.
The same budget will make it possible to strengthen 2 times more apartments
The person who initiated the pilot is Tali Hirsch Sherman, director of the Department of Construction Theory and Engineering Development. The wing she heads serves, among other things, as an executive arm of the Inter-Ministerial Steering Committee for Earthquake Preparedness.
Hirsch Sherman tells Calcalist in an interview held last week at the Ministry of Construction in Tel Aviv that the first step to implementing the method began two years ago: "We were asked by the Inter-ministerial Committee for Earthquake Preparedness to update the standard for strengthening existing buildings. There has been such a standard for several years, but it is lacking and included only one classical method.We decided to introduce into the standard advanced strengthening methods that are used in countries that experience many earthquakes such as Japan, Greece and Italy.
Today, the new standard appears in TMA 38, and contractors can use the advanced methods. The problem is that there is not enough knowledge in this field in Israel, the methods are not taught in engineering faculties. The pilot and a dedicated course that we opened last year and will also open next year will make it possible to transfer the knowledge to the private sector as well."
The new method is intended for strengthening old buildings that were built before the construction standard for the resistance of buildings against earthquakes came into effect, and is not relevant to buildings that are destroyed and rebuilt according to the standard that came into effect in 1980.
Estimates in the industry are that the conventional method for strengthening buildings is not good enough. Last month, a discussion was revealed in "Calcalist" in which the words were explicitly stated by the chief architect of the Ministry of Construction and Housing, Ward Solomon, from Vigal Govrin, the chairman of the Union of Engineers. Therefore, TMA 38 and the urban renewal policy that will replace it in the coming years will encourage demolition and rebuilding Over strengthening an old building.
However, in Israel there are tens of thousands of buildings that have a very low chance of undergoing a demolition and rebuilding project. Among other things, because they are in areas where it is not economically viable to demolish and rebuild, and also because sometimes there are planning limitations that prevent such a project.
The report of the Ministry of Construction shows that the new method provides a better answer against earthquakes than the conventional one. If the private sector adopts the new method, many buildings can be strengthened. In a conversation with "Calcalist" Benny Dreyfus, CEO of the Ministry of Construction, says: "This thing has many other meanings, it may be that in places where the private market will adopt the method we will not need an addition of 2.5 floors, maybe only 1.5 floors and then the whole discussion about planning and infrastructure changes ".
The private sector does not operate in the far periphery, because the absolute majority of projects to strengthen buildings in the periphery are carried out with the meager budget that the Ministry of Construction has for the purpose. In recent years, the annual budget was six million shekels for each of the six peripheral cities that are located in areas defined as being at high risk of earthquakes, including Eilat, Beit Shean, Tiberias, Safed, Kiryat Shmona and Hazor of the Galilee.
"Our challenge in 2020 is to take the few budgets we had in the six cities that are on the Syrian-African divide, and with the same money to double the apartments," Dreyfus says.
Link to the article:
https://www.ynet.co.il/articles/0,7340,L-5629404,00.html