Teknisia

Laboratory Model Test on The Sand Column for Reinforcement System of Flexible Pavement

Yuli Fajarwati — 2023-12-30

Flexible pavement failures in Indonesia are primarily attributed to weak subgrade conditions, necessitating soil reinforcement measures. This study aimed to enhance soil-bearing capacity through soil reinforcement experiments utilizing a mixture of sand columns, rice husk ash, and cement. A prototype was constructed, including a 1×1×1 m steel box, an IWF steel frame, a dial gauge, a steel plate, and a proving ring, to apply a load to soil arranged within the iron box using a 3-ton hydraulic jack. The study focused on a clay soil type (following the AASHTO method) and conducted soil reinforcement in four scenarios. The result shows that in all scenarios involving a sand column, Scenario 1: 3% sand, 3% rice husk ash, and 6% cement obtained a q_ult is 0.23 kg/cm² and BCR 114.94%; Scenario 2: 3% sand, 6% rice husk ash, and 3% cement obtained a q_ult is 0.12 kg/cm² and BCR 11.49%; Scenario 3: 6% sand, 3% rice husk ash, and 3% cement obtained a q_ult is 0.14 kg/cm² and BCR 26.44%; Scenario 4: 6% sand, 6% rice husk ash, and 0% cement obtained a q_ult is 0.24 kg/cm²and a BCR of 116.09%. Notably, scenario 4, featuring a column composition of 6% sand, 6% rice husk ash, and 0% cement, achieved a significant increase in bearing capacity (q_ult) with a value of 0.24 kg/cm² and a high Bearing Capacity Ratio (BCR) of 116.09%. Scenario 1 was the most effective in reducing moisture content by 4% relative to the original soil moisture content, with a mixture comprising 3% sand column, 3% rice husk ash, and 6% cement. The findings suggest that applying soil columns can enhance the performance of flexible pavements.

Investigation of Effective Section Reduction in Low Carbon Steel during SMAW Welding

Malik Mushthofa — 2023-12-30

Welding, with its advantages of expedient execution and reduced weight, is a favored method for structural connections. However, it poses a significant risk, softening the steel and diminishing load-bearing capacity, underscoring the importance of accurate estimation. The need for precision is paramount, as critical infrastructure must remain operational not only during disasters but also during repair and maintenance activities. To address this challenge, this research introduces an approach to estimate the extent of capacity reduction resulting from welding, providing engineers with valuable insights for maintaining these critical systems structural integrity and functionality.

The study examined low-carbon steel with various thicknesses, focusing on Heat Affected Zone (HAZ) width calculations and Abaqus simulations. Welding was performed at a speed of 1.67 cm/s with a 5 mm element increment. This research aimed to investigate the impact of welding parameters on low-carbon steel, particularly concerning HAZ measurements. A 4 mm-thick plate generated a 38.73 mm affected zone, while simulations with 5 mm to 12 mm thicknesses produced progressively narrower affected zones. Results demonstrated that steel plate thickness significantly influences the affected zone width, with thicker plates yielding narrower affected zones.

The study examined low carbon steel with a 4 mm thickness, focusing on Heat Affected Zone (HAZ) width calculations and Abaqus simulations. Welding was performed at a speed of 1.67 cm/s with a 5 mm element increment. The research aimed to investigate the impact of welding parameters on low carbon steel, particularly concerning HAZ measurements. Results demonstrated that steel plate thickness significantly influences the affected zone width, with thicker plates yielding narrower affected zones. A 4 mm-thick plate generated a 38.73 mm affected zone, while simulations with 5 mm to 12 mm thicknesses produced progressively narrower affected zones.

Analisis Aselerasi Riwayat Waktu pada Wilayah Spesifik di Yogyakarta dengan Sumber Gempa Subduksi Berdasarkan Peta Gempa 2002

Wisnu Erlangga — 2023-12-30

Indonesia is a country that is very prone to earthquake disasters. Earthquakes cause damage especially to buildings. In building planning, the usual earthquake load is the earthquake load from the spectral response. The use of earthquake loads from time history is very rarely used because of the difficulty of finding accurate data for an area. In this study, Alana Hotel and Apartment were chosen as research objects to find artificial time history. All earthquake data affecting Yogyakarta region were collected from several sources. Seismic hazard analysis in this study uses the PSHA (Probabilistic Seismic Hazard Analysis) method by calculating the main earthquake only. The selection of attenuation functions is based on the similarity of geological and tectonic conditions in Indonesia. These attenuation functions produce a seismic hazard curve and a uniform hazard spectrum response. The selection of time history data for bedrock is based on the results of the deaggregation process in the form of dominant magnitude and dominant distance from the subduction earthquake source. It is necessary to adjust the spectrum response in the time history data to fit the research location. Furthermore, earthquake waves from the bedrock are propagated to the surface. The results show that the peak time history acceleration value after surface propagation increased by 1.51 times than the time history in bedrock.

Analisis Potensi Penggunaan Moda Transportasi Tidak Bermotor Pada Mahasiswa di Kampus Terpadu Universitas Islam Indonesia

Prayogo Afang Prayitno — 2023-12-30

The large number of students is directly proportional to the increase in private vehicles on campus, resulting in traffic congestion. Efforts should be made to encourage motorized vehicle users to switch to sustainable modes of transportation. This study aims to determine student dependence on motorized vehicles to go to campus and identify factors associated with using sustainable modes of transportation at the Universitas Islam Indonesia (UII). The data sample consisted of 614 respondents, collected through online simple random sampling. The collected data were then analyzed using the Chi-Square test. The survey data reveals a significant reliance on motorized vehicles to get to campus, with 67% of trips within a 2-kilometer radius made by motor vehicles. Based on the Chi-Square test results, factors such as motor vehicle ownership, driving license ownership, travel distance, and the primary mode of transportation are strongly associatedwith the willingness to walk or cycle. This condition indicates that practicality or habitual aspects have a stronger relationship with students' willingness to use sustainable transportation than demographic or socioeconomic factors. Thus, efforts are needed to increase the practicality of using sustainable transportation to optimize sustainable campus development.

Analisis Fluktuasi Jumlah dan Karakteristik Penumpang Bus Trans Jogja Kondisi Sebelum, Selama, dan Setelah Covid-19

Rizki Budi Utomo — 2023-12-30

Trans Jogja Urban Public Transportation is a form of reform of the subsidized road transport system in the Special Region of Yogyakarta, which has served the Yogyakarta Urban Area since 2008. Trans Jogja Buses have served 25 sub-districts, with a fleet of 128 buses subsidized by the DIY Regional Government and 44 buses subsidized by the Ministry of Transportation of the Republic of Indonesia. When the COVID-19 pandemic hit in 2020-2021, there was a decrease in people's movements, resulting in a decrease in Trans Jogja Bus passengers. This study aims to analyze the fluctuations of passengers and compare the characteristics of the Trans Jogja Bus passengers in conditions before COVID-19 (in 2019), during COVID-19 (in 2020 and 2021), and after COVID-19 (in 2022). The analysis results show that based on the monthly average, the number of Trans Jogja Bus passengers in conditions during COVID-19 decreased by 54%. After COVID-19, it increased by 12% compared to during COVID-19. The monthly average number of passengers After COVID-19 is not as regular as in conditions before COVID-19, with a disparity of 50%t. Based on the characteristics of passengers during COVID-19, the proportion of missing passengers is by the professional aspect, namely students/students and civil servants/national soldiers/police. Regarding travel intentions, a relatively large proportion of the missing were college, school, and tourism travel, each decreasing by 7%.

Pengaruh Penambahan Vermikulit pada Beton Normal Terhadap Kuat Lentur Balok Terdukung Sederhana

Lintang Dian Artanti — 2023-12-30

Concrete innovation in the construction industry continues to grow until now. One of the substantial innovations made is adding a material called vermiculite. If changes in compressive strength of concrete were observed in the previous study, then changes in concrete weight and flexural strength of concrete with the addition of vermiculite as much as 12%, 24%, and 36% were observed in this study. Concrete specimens were cured with water for 28 days and then weighted and tested for flexural strength with two loading points. The test results show that the lightest concrete is found in concrete with the addition of 36% vermiculite, with a weight difference of 0.03% lighter than normal concrete. Based on the results of the flexural strength test, the addition of 36% vermiculite makes the flexural strength of concrete 42.75% higher than normal concrete. This improvement proves that vermiculite's high water absorption properties can reduce the excess water content in concrete to reduce its weight, making the concrete denser and increasing its flexural strength.