Effectiveness to Additional Cost on The Implementation of Seismic Resistance Features For Residential Houses

Abstract

Many residential houses in Indonesia have been collapsed during earthquake because they do not implement seismic features correctly. Although the implementation of seismic features will add construction cost, people need to better understand about the benefit which is acquired through this additional cost. This paper presents the effectiveness of additional cost for the implementation of seismic features for residential house using benefit-cost ratio method. There were 10 existing houses in Sleman District as samples which had seismic features. To achieve an easy measurement of the benefit, the existing houses were also assumed to be unreal or virtual houses which did not have seismic features. The benefit was measured by the difference of damage cost, if an earthquake happened, between the seismic featured existing houses and the non-seismic featured virtual houses. Damage cost was expressed as percentage damage multiplied by collapsed house replacement cost. Damage percentage is comprised by damage state which was done by subjective judgment to four earthquake experts who had got actively involved in disaster management in Yogyakarta 2006‘s earthquake and damage ratio presented in FEMA. House replacement cost followed the current Yogyakarta cost standard. Additional cost has been accomplished by the cost of seismic features which included cost of tie beam, column, lintel beam, and ring beam. The findings have shown that the average benefit-cost ratios on earthquake scenarios on year-0, year-10, year-20, year-30, year-40, and year-50 are 14.63; 17.47; 20.87; 27.27; 37.35; and 52.90 respectively. This finding depicts that the additional cost is truly effective to reduce the damage which is expressed by regression equation Y = 13.53.x 1.026x which indicates that benefit-cost ratio (y-axis) will increase exponentially whenever the span of time for occurring earthquake (x-axis) is longer.