New precast building withstands the millennium earthquake
The Pacific Ring of Fire is a volcanic belt, which rings the Pacific Ocean on three sides for a length of over 40,000 km. The friction of the tectonic plates makes this region a zone of frequent earthquakes, which in recent past have caused large numbers of buildings to collapse and this is a permanent threat for the people living in these regions. Indonesia with its population of more than 250 million inhabitants and millions of tourists, who come to visit each year, is one of the most severely affected countries in this region.
Therefore it was all the more important for the leading property developer, PT Modernland, which is a member of the Modernland Group, Indonesia; and which has recently entered the field of precast concrete element manufacture, to make the topic of earthquake-proof construction a central aspect in the planning of its new precast concrete element premises and of its overall projects. As well as planning for the eventuality, the company insisted on an actual seismic test on a test building at a construction material-testing laboratory in Bandung. The aim of the test was to analyse the behaviour of the house under extremely high seismic activity, in order to be able in the future to offer its customers a safe precast concrete element house and construction system with load-bearing walls.
Three earthquake magnitudes simulated
The test simulates three earthquake magnitudes. In the first test phase, the house was subjected to seismic activity of the type, which occurs every 500 years. In the second test phase, the house was tested against the type of earthquake, which occurs on average every 2,500 years; this corresponds to a magnitude of more than 8 on the Richter scale. In a third phase, the house was tested up to the total yielding point or to the maximum of the laboratory‘s testing capacity.
In preparation for the tests, during production more than 200 load meters were integrated into the various precast concrete elements, in order to provide the laboratory with a flow of data during the tests. Numerous cameras in the interior and on the exterior of the house allowed the scientists to see what was happening as the test progressed. The seismic magnitudes were simulated with the aid of a hydraulic system, which provided the energy for the loading conditions.
Precast concrete elements for safety
The test result was positive. The sound, considered static planning and technology of the building, together with the professional production of the house in PT Modernland‘s new Ebawe precast concrete plant produced the result that even in the case of the earthquake of the type, which occurs only every 2,500 years, the building showed only minor damage in the form of hair-line cracks and local spalling in the assembly gaps in the outer wall of the building. There was at no time any risk to persons. Even in the case of the heaviest test, loading the house withstood the seismic forces. On conclusion of the „Earthquakes every 2,500 years“ test stage the test building passed with flying colors with a classification of I.O. (Immediate Occupancy).
The positive test results mean that PT Modernland will in the future be one of the first companies in Indonesia to be authorized to construct multi-storey precast concrete element buildings with load-bearing walls. This successful earthquake test has confirmed and boosted confidence both within the company and among its potential customers in the possibilities for safety opened up by constructing with precast concrete elements.
