Resistance Factor and Target Reliability Index Calculation of Static Design Methods for Driven Steel Pipe Pile in Gwangyang

공식의 저항계수는 각각 0.611∼0.684, 0.821∼0.537, 선단부 N치 50이상인 경우 각각 0.608∼0.545, 0.749∼0.643으로 제안되 었다. 본 연구결과는 향후 다양한 기초구조물 및 지반구조물의 하중저항계수설계법 개발을 위한 자료로서 그 활용성이 있을 것이다. Abstract Recently, the necessity of developing the load and resistance factor design(LRFD) for soft ground improvement method has been raised, since the limit state design is requested as international technical standard for the foundation of structures. In this study, to develop LRFD codes for foundation structures in Korea, target reliability index and resistance factor for static bearing capacity of driven steel pipe piles were calibrated in the framework of reliability theory. The 16 data(in Gwangyang) and the 57 data(Korea Institute of Construction Technology, 2008) sets of static load test and soil property tests conducted in the whole domestic area were collected along with available subsurface investigation results. The resistance bias factors were evaluated for the tow static design methods by comparing the representative measured bearing capacities with the expected design values. Reliability analysis was performed by two types of advanced methods : the First Order Reliability Method (FORM), and the Monte Carlo Simulation (MCS) method using resistance bias factor statistics. As a result, when target reliability indices of the driven pipe pile were selected as 2.0, 2.33, 2.5, resistance factor of two design methods for SPT N at pile tip less than 50 were evaluated as 0.611∼0.684, 0.537∼0.821 respectively, and STP N at pile tip more than 50 were evaluated as 0.545∼0.608, 0.643∼0.749 respectively. The result from this research will be useful for developing various foundations and soil structures under LRFD.