LIQUEFACTION RISK ASSESSMENT AND DESIGN OF PILE FOUNDATIONS BASED ON CPT DATA (A CASE STUDY) Putera Agung M Agung Civil Engineering Department State Polytechnic of Jakarta (PNJ) Kota Depok, Indonesia E-mail: putera_agung2002@yahoo.com Andreas Rudi Hermawan Civil Engineering Department State Polytechnic of Jakarta Kota Depok, Indonesia E-mail: arudihermawan@gmail.com Abstract— Based on Indonesian Code (SNI 1726: 2012), Indonesia has a strong earthquake risk. One of the dangers faced in planning the building on sand soil conditions is liquefaction. Indonesia has a lot of fluvial deposits containing potentially liquefiable clean sand and silty sand in a medium-dense to loose state with an variation of thickness from 10 to 30 m. Current state of practice of semi-empirical methodologies based on CPT profile is applied to access the safety factor against liquefaction, and are compared with results of theoretical 1−D nonlinear effective stress analyses. The consequences of liquefaction on foundation piles are determined on successive stages: “before”, “during”, and “after” liquefaction, including lateral spreading, in a simplified way. Three different ‘design’ profiles are assigned but only one of them is used in this paper for 1−D equivalent−linear and nonlinear seismic response analyses. Keywords—earthquake, liquefaction, ETABS 2000, sandy soil, pile. I. INTRODUCTION A. Background The Indonesian Archipelago has several distinctive features that make the region one of the most active tectonic zones in the world. Three tectonic plates converge in the area leading to complicated geological and tectonics mechanisms (Fig.1). The typical island arc structure with its unique physiographic features together with earthquake hypocenters along dipping Benioff Zones, adds a more challenging condition for the area. With respect to the island of Java, there are also some potential active inland surface fault distributions. Seismotectonic Fig. 2. indicates the high historical seismicity of the Indonesia regions. Especially. Table 1 summarizes the activity both for the fault and subduction zone influencing Jakarta city. In recent years, Indonesia has experienced several major earthquakes, some of these events struck large cities where relatively modern buildings have been constructed and were expected to resist the earthquake effects and shocked many people caused extensive damage even to modern engineered structures. A major contributing factor to this widespread damage seemed to be the automatic usage by engineers of the code based seismic response modification (reduction) factor R, without fully understanding or following all of its prerequisites, primarily ductile design and detailing. It can be expected that buildings designed and built in such a manner are unlikely to remain undamaged or even standing following a proximate large earthquake. Recognizing this fact, the government of Indonesia has carried out a process of developing modern codes for earthquake resistant structures. The first such modern comprehensive code, Code of Seismic Resistant Design for Buildings, was introduced in 1983 by the department of Public Works to replace the then existing 1970 Indonesia Loading Code N.I-18 (NI-18, 1970). It was later replaced by 2002 Code on Seismic Resistant Design for Buildings, SNI-03-1726-2002 (SNI-1726, 2002). This code adopted many of the UBC 1997 (UBC, 1997) criteria for earthquake design. This code has now been completely revised and a comprehensive update based primarily on the ASCE 7-10 Standard (ASCE/SEI, 2010) has been issued as the Indonesian Code SNI-1726, 2012. B. Earthquake-induced pile loads Piles are generally viewed as an acceptable foundation solution in liquefiable ground, and there are numerous case histories of piled foundations performing well where soil has liquefied. However, there are also case histories of piles with inadequate resistance to the additional loads imparted by liquefied soil and the associated loss of support. The design of piles in liquefiable soils requires careful consideration, both of the behaviour of the piles themselves and the impact on the supported structures. This paper presents a comprehensive review of two issues faced by an earthquake engineer designing piles in such zones. Firstly, what are the statutory requirements? National and international standards and guidance documents are reviewed, and specific requirements for pile design and performance, are