New construction system withstands even millenium 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 here. Indonesia with a population of more than 250 millions inhabitants and millions of tourists, each year, is one of the most severely affected countries. It was very important for the leading property developer, PT Modernland, which is a member of the Modernland Group and has recently entered the field of precast concrete element production, 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 simulation on a test building at a construction material testing laboratory in Bandung. The goal was to analyze the behavior of the house under extreme high seismic activity, in order to be able to offer its customers a safe precast concrete element house or construction system with loadbearing walls in the future.
Three earthquake magnitudes were simulated. In the first test phase the house was subjected to seismic activity, which occurs every 500 years. In the second 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. Potentially in a third and last phase, the house will be tested up to the total static 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 different loading conditions.
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 be one of the first companies in Indonesia to be authorized to construct multi-storey precast concrete element buildings with load-bearing walls in the future. 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.