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Dynamic Analysis of Force Redistribution in Small Pile Groups Foundation Subjected to Accidental Lateral Loads Nathaniel Wilmer, Reynaldo; Adi Prakoso, Widjojo
Jurnal Teknik Sipil Vol 31 No 2 (2024): Jurnal Teknik Sipil - Edisi Agustus
Publisher : Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/jts.2024.31.2.2

Abstract

Abstract Designing infrastructure always involves considering potential loads. Beyond anticipated loads, accidental ones can occur, as with the Pedamaran II bridge in Riau, where a ship collision damaged its foundation, breaking a pile and cracking the pile cap. However, this did not lead to structural failure, even though over 30% of the piles in the group were damaged. Initial hypotheses suggest that the use of bracing in the existing bridge might have helped redistribute forces. A numerical model was created using Opensees to simulate lateral loading on the shaft of an elevated pile cap, comparing the effects of bracing and no bracing using elastic elements in a simple 2x2 foundation model. The aim was to understand the correct modeling approach for bracing behavior and its impact on load response. Pushover analysis was performed on one of the shafts, with eccentric loading generating forces in both the x and y axes. Results showed that modeling bracing with elastic elements helped evenly distribute forces across rows of piles, with the greatest distribution occurring in the loaded row. The maximum moment occurred at the lowest bracing connection, highlighting the crucial role of bracing in load distribution, and significantly increasing lateral capacity by about 60%.
Efektivitas Drainase Vertikal sebagai Mitigasi Likuefaksi dalam Ragam Potensi Percepatan Tanah Maksimum Renatra, Chariznantya; Adi Prakoso, Widjojo
Jurnal Teknik Sipil Vol 32 No 3 (2025): Jurnal Teknik Sipil - Edisi Desember
Publisher : Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/jts.2025.32.3.1

Abstract

Abstract Lolu Village, located in the Palu Koro fault groove and has a stratification of soil sediment that is layered with heterogeneous characters. Between the cohesive and granular soils, forming an overlapping layer. Lolu Village has its own challenges in dealing with the potential for earthquakes and liquefaction as a result. One of the liquefaction mitigations in SNI 8460:2017 is stone columns (SC) as a vertical drainage medium that functions to accelerate the rate of pore water dissipation. However, the condition of the layered soil interspersed with cohesive soil with low permeability, presents its own challenges in determining the depth of stone columns. It is necessary to review the extent of the effectiveness of SC against Peak Ground Accelerations (PGA) that have the potential to occur in Lolu Village. The stratification of the soil and stone columns will be modelled using the Midas GTS NX. Soil layers with liquefaction potential use the UBC Sand model and SC with the Mohr Coulomb model. When the stratification modeling of the soil was shaken by cyclic loads, it was found that only the upper granular layer was liquefaction. This identifies that the thin layer of cohesive soil between the layers of granular, has a role as a shield to resist the pore water pressure of the granular soil layer underneath. The study compared the initial soil conditions against two variations in the depth of SC. It was found that the depth of the SC was passed through the thin layer of cohesive soil between the granular layers, worsening the liquefaction condition of the upper layer. Keywords : Liquefaction, Midas GTS NX, Pore Pressure Ratio PPR, stone columns
Land Use/Land Cover Changes Using Landsat Imagery in The Upper Citarum Watershed, West Java, Province, Indonesia Marko, Kuswantoro; Sutjiningsih, Dwita; Kusratmoko, Eko; Adi Prakoso, Widjojo
International Journal of Remote Sensing and Earth Sciences Vol. 22 No. 1 (2025)
Publisher : BRIN

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30536/ijreses.v22i1.13539

Abstract

The growth of the population and its activities, especially in the Upper Citarum Watershed (UCW) since the last decade has changed the condition of land that was originally vegetated into built-up land. Uncontrolled land use/land cover (LULC) changes in this watershed will certainly have an ecological and hydrological impact. Moreover, this watershed has a very vital role as a provider of agricultural products and water sources in three large reservoirs on the Java island, i.e. the Saguling, Cirata, and Jatiluhur reservoirs. The existence of these three reservoirs is very reliable in supplying electrical energy for the islands of Java and Bali. This study aims to determine changes in LULC over the last 30 years period (1990-2020). LULC information was obtained from analysis of Landsat imagery in 1990, 2000, 2010 and 2020. Supervised classification methods based on remote sensing and geographic information systems were applied to identify types and changes in LULC, i.e. forests, rice fields, dry farm land, bush-grass, mixed gardens, built-up land, and water bodies. The results showed that during the last 30 years there was a fairly high increase on built-up land (+16.4%), and a fairly high decrease in rice fields (-11.5%). The high increase in the ​​built-up land from 1990 to 2020 is indicated by the high level of land conversion from rice fields and dry land farming. The area of ​​natural LULC such as forest has decreased by -3.2% or about 5,705 ha in the last 30 years. The results of this study are expected to be a reference for the government and environmentalists so that efforts to prevent environmental damage can be carried out early on.