Tendency Created by Public Aid and General Contractors
After the Great Hanshin Earthquake, many condominiums were damaged and demolished. Some of them were scrapped even when not necessary. The first reason for the demolition of these restorable buildings and the new construction lay in the governmental policy. It was subsidized by public money to demolish damaged buildings if the operation was to be done within a year after the earthquake. Many condominium owners associations were led to the demolition of their condominiums to save the cost, estimated to be two to three million yen per household, without any in-depth discussion. The second reason was that consultants and general contractors steered many condominium owners associations towards scrap and build from the point of view of the creation of jobs.
Pilotis Repairable by Jacking up
Condominiums of a structure with a piloti on the ground floor incurred especially severe damage. It is, however, possible to jack up the building horizontally to repair and reinforce the broken pillars by diagonal bracing and steel piping. The utilization of jacks is a technology established in the 1964 Niigata Earthquake in the Chubu region, Japan, but was not well-recognized in the Kansai region. This probably was one of the reasons for the increase in the unnecessary demolition of condominiums. It is also desirable to make pilotis quake-resistance before the building experiences a disaster. The cost of reinforcement work by the installment of bracing and/or steel piping is quite reasonable -- several hundred thousand yen per household, partially due to the fact that work is required only for the ground floor with little need for temporary works.
Repair Cost Much Lower than Reconstruction Cost
The cost of reconstruction and repair for a condominium by the city is indicated in Table 2. The repair cost is three million yen or less even for a building which received rather severe damage. Even in the worst case, it is around 10 million yen. On average, it is 15% or less of the cost of reconstruction, without the cost of demolition included. It is plain that the cost of restoration with reinforcement works is a much less burden to the residents than the cost of demolition and rebuilding, which is a method too easy to choose. (Data reference in this section: NISHIZAWA Hidekazu, lecturer at Kyoto university)