Indonesia has been struck by earthquakes many times. However, the real action to reduce building vulnerability is still minimal. Until now, there is no significant effort done on the buildings which have same or higher level of seismic threat in other region. â€œIt seems that no real action has been done, so there is the possibility of similar earthquakes in other regions as in Padang,â€ said Prof. Dr. Ir. Iman Satyarno, M.E when inaugurated as professor of Faculty of Engineering, UGM, Monday (22/2) at UGM Senate Hall.
Iman mentioned in his inauguration speech entitled â€œEvaluation and Reduction of Building Vulnerability in Earthquake Mitigationâ€ that in earthquake mitigation the action done is rapid visual evaluation. The following action is detailed seismic evaluation and reconstruction and clearance. Iman added that if building performance does not meet feasibility requirement and there is no reconstruction because it is not more economical, the building should be demolished or build a new one.
Further the lecturer of Civil Engineering Department said that repair on vulnerable building can be done by reducing earthquake burden that occurs, strengthening the structure and repair mechanical part. Repair by reducing the burden can be done by reducing the burden of the building itself, such as changing the function of the building, using light material, reducing the number of floors, and giving basic isolation. The reduction of seismic force by reducing self-weight can occur because the seismic force is the same with the weight of the building.
The man born in Bandung on 23 January 1963 mentioned that styrofoam concrete is the light material that can be used for wall installment, because it is light and more dactyl than brick. Therefore this concrete is suitable for wall material in earthquake-prone regions. Besides, it can be utilized as alternative of buildingâ€™s finishing in location with potential liquefaction.
Meanwhile, basic isolation can be applied to reduce seismic force because the buildingâ€™s vibration time can be longer. In addition to reduce structural destruction, basic isolation is also used to reduce mechanical, electrical and architectural destructions due to the reduction of floor velocity. Unfortunately, this method has not been commonly used in Indonesia.
Building vulnerability can also be reduced by strengthening the structure in several ways. For simple brick-walled house, the strengthening can be done using chickenwire and polypropylene and plastered with mortar. Iman said that this method is appropriate for simple house that can not fulfill earthquake resilient requirement. Besides the easy application, it is also inexpensive.
For intricate building, the strengthening is by combination of actions such as adding dimension, new material or new structure. â€œIt is important to note that this should be done carefully, because besides changing the strength, it also changes the structure's stiffness, attenuation, and dactylity. Material used to strengthen the structure should have higher elasticity of modulus and power than the strengthened structure,â€ he explained.Â