ANALISIS POTENSI LIKUIFAKSI DENGAN PENDEKATAN PROBABILISTIK (PERFORMANCE-BASED EVALUATION) DI KOTA PADANG, SUMATERA BARAT

Evaluation of liquefaction potential by the conventional way are based on deterministic methods. The methods use only one condition of earthquake load as parameter in liquefaction analysis. Actually, the strength of earthquake loads are varies. In the other words, there is the uncertainty magnitude of earthquake loading. The uncertainty can be taken into analysis only by using a probabilistic approach. This study describes how to analyze liquefaction by probabilistic method. The method used was performance-based evaluation, developed byKramer and Mayfield (2005, 2007). This method include contributions from all levels of magnitude earthquake (hazard levels) in liquefaction analysis. The research location is in Padang, West Sumatra. Soil Investigation data used are N-SPT and shear wave velocity spread in the city of Padang. Earthquake load parameters used were obtained from PSHA and deagregation analysis. The results of this study show the variation of liquefaction potential across the city of Padang based on liquefaction return period. The location with great potentialfor liquefaction (FS <1) by the probability more than 50% were in the coastal region and northern parts of Padang

Reabilitas Daya Dukung Pondasi Tiang Bor Berdasarkan Formula Reese & Wright dan Usulan Load Resistance Factor Design dalam Perencanaan Pondasi Tiang Bor Studi Kasus Proyek Jakarta

Design bored pile foundation often use formulae of Reese and wright (1977) on projects heild in Jakarta. The safety factor often use on the design foundation on project in Jakarta are generally 2 or 3. By using advance First Order Liability Method to analysis design foundation, the result showed that the design was very conservative. Proven by the safety index for this design is 2.68 where’s the equivalent of failure probably 3.72 x 10-3, this result is less than requirement of failure probability 1 x 10-2. Lastiasih (2012) propose the use of multiple safety factors by applying Load Resistance Factor Design (LRFD) in accordance with the design of building age so as not to use single safety factor again. Further more the design of bored pile foundation become more efficient