Development of performance-based design code for concrete structures in Indonesia

Abstract

Nowadays, global trend on code of practices tends to be performance-based code. Performance-based design means the methodology, which is based on sufficiently realistic environmental and material models so it is possible to make satisfactory prediction of the future behavior of a concrete structure under its service conditions. This research was aimed to determine the partial safety factors used on verification of performances for concrete structures in Indonesia. The research starts with data collection of material of reinforced concrete structures, fabrication level, and some parameters to reflect workmanship in construction. Statistical analyses on those data in conjunction with Monte Carlo Simulation are required to study the statistical characteristics, then compared with similar information from Japan, and some others available. Using those characteristic values of material, fabrication, member strengths, and characteristic of actions from the literature, reliability analysis then carried out. The result of reliability analysis became input on determining the partial safety factors for performance indices as for strength, serviceability, and durability. This research showed the material production and fabrications of structural members for typical buildings in Indonesia are not far behind developed countries; even though always need to be improved. The data of fabrication show that the condition of workmanship in Indonesia could be similar trends of those for Japan, however it may be slightly poorer than those for Europe and the United States. Furthermore, partial safety factor for structural member for Indonesia would rather be bigger than those from Europe due to high variability in material production and fabrication. Global partial safety factor for strength for Indonesia are γM = 1.5 to 1.7 for concrete compressive strength and 1.1 to 1.15 for steel in tension. Partial safety factor as multiplier of calculation result for cracks width, deformations and vibrations (natural frequency) are 1.05, 1.10, and 0.95 respectively. The partial safety factor for durability has been introduced by α as an indicator and magnifier for standard concrete cover to be 1.20, 1.00, and 0.80 for fc ‘ less than 25 MPa, 25 – 40 MPa, and more than 40 MPa respectively. These performance indices have shown its conformance to the existing the Limit State Design Code and they become the firs step in developing the performance-based design code in Indonesia.