PENGARUH DENSITAS ARUS TERHADAP PERILAKU RETAK BETON BERTULANG YANG MENGALAMI KOROSI TULANGAN

Abstrak Korosi pada struktur beton betulang dapat mengurangi kinerja struktur dan umur layannya karena volume tulangan yang berkurang. Besarnya jumlah korosi yang dipengaruhi oleh laju korosi dapat digambarkan melalui besarnya densitas arus yang terjadi. Jumlah korosi yang terjadi mempengaruhi perilaku retak pada beton bertulang, oleh karen itu, pada studi ini dilakukan uji eksperimental untuk mengevaluasi pengaruh densitas arus terhadap perilaku retak permukaan beton dari struktur beton bertulang yang mengalami korosi tulangan. Pengujian dilakukan dengan mengaplikasikan variasi densitas arus yaitu 900 µA/cm2, 500 µA/cm2, 200 µA/cm2 and 100 µA/cm2 pada pengujian korosi secara elektrik menggunakan larutan NaCl sebagai elektrolit untuk menghasilkan ion Cl-. Benda uji yang digunakan adalah balok dengan luas penampang 150x150 mm2 dan panjang benda uji 300 mm. Tulangan baja diameter 19 mm digunakan pada tengah penampang. Hasil pengujian menunjukkan bahwa perilaku retak dari beton bertulang yang mengalami korosi pada tulangannya memiliki kurva yang bilinear. Selain itu, hasil pengujian menunjukkan bahwa densitas arus yang rendah memiliki kecepatan retak permukaan beton yang lebih tinggi jika dibandingkan dengan benda uji dengan menggunakan densitas arus yang tinggi. Kata kunci: korosi, beton bertulang, produk korosi, retak, densitas arus Abstract Corrosion in reinforced concrete structure can reduce structure performance and its service life due to rebar mass loss. Corrosion amount influenced by corrosion rate can be figured out by using current density. Corrosion amount influences the crack behavior of reinforced concrete, therefore, in this study, experimental study was performed to evaluate the effect of current density to surface concrete cracking behavior of corroded reinforced concrete structure. Accelerated corrosion test tests were conducted with various current density. It was 900 µA/cm2, 500 µA/cm2, 200 µA/cm2 and 100 µA/cm2. NaCl solution was used as electrolyte to produce ion Cl-. The specimens were beam with cross section area 150x150 mm2 and 300 mm in length. Rebar with diameter 19 mm was applied in the center of specimen. The results showed that cracking behavior of corroded rebar has bilinear curve that shows the effect of corrosion products movement through cracks. Furthermore, lower corrosion rate has higher cracking speed than higher corrosion rate. Keywords: corrosion, reinforced concrete, corrosion products, cracking, current densit

Children's Environmental Waste Reduction Education Rawa Simprug IX, South Jakarta, Special Capital Region of Jakarta to Increase Public Awareness of Environmental Issues

ABSTRACT Education is something that serves as a foundation for humans. As educational activists, we can raise a better generation by conducting teaching activities for the nation's children to hone their academic and non-academic abilities outside formal schools. The large number of students dropping out of school causes non-formal education to have an important role in fostering environmental awareness. This activity aims to foster a sense of concern for environmental knowledge, especially among children in Rawa Simprug IX, South Jakarta, Special Capital Region of (DKI) Jakarta. In addition, it also aims to enhance children's interest in reading from an early age and their understanding of various lessons that have been or have not been obtained in formal schools. This activity was conducted from August 2019 to November 2019. The peak of the event was held on Sunday, November 24, 2019. In this activity, several books could be loaned to children for on-the-spot reading (in the Madani Rubric). The book was carried by a mobile library car from the South Jakarta Administration City Library and Archives Service. There were approximately 30 children of Rawa Simprug IX who took part as the participants in this event. This activity teaches children in the Rawa Simprug IX area who need additional education with the help of HMTL (Himpunan Mahasiswa Teknik Lingkungan) and some lecturers from Pertamina University as the teaching staff. The children were also taught about the environment, particularly reducing plastic waste by using drinking bottles. The achievement of this activity is a recycling product made by the target community themselves

Effect of Nutrient Inputs on Water Quality Change and Phytoplankton Growth in Atsumi Bay

Eutrophication in an estuary occurs as an effect of the enrichment of nutrient inputs from rivers. This condition has become one of the most common environmental issues experienced around the globe and especially in Japan. Atsumi Bay is a eutrophic coastal area in Japan. The objective of this research was to analyze the influences of nutrient inputs from the Umeda River into Atsumi Bay on pre- and post-rainfall water quality conditions. This study was conducted from July to October 2010. The results showed a decrease of surface salinity after rainfall indicating that huge freshwater inputs had overlaid the surface layer of Atsumi Bay rather than the bottom layer. Moreover, post-rainfall conditions showed an increase of chlorophyll a as an effect of phytoplankton growth, followed by an increase of particulate nutrients. On the other hand, dissolved nutrients decreased due to uptake by phytoplankton and dilution by freshwater

Evaluation of Phytoplankton Growth in Estuary as Effect of Nutrient Inputs during Rainfall Using Ecological Model

豊橋技術科学大

Pengaruh biaya faktor dan tenaga kerja terhadap pendapatan usahatani padi sawah di kecamatan Montasik kabupaten Aceh Besar

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Landslide tsunami impact assessment toward human lives using numerical modelling: A case study from Banten, Indonesia

After the eruption of Mount Anak Krakatoa, December 22, 2018, which was accompanied by a large landslide into the waters of the Sunda Strait, resulting a tsunami that hit South Coast of Lampung and West of Banten. According [1], 437 peoples were death, 31,942 peoples were injured and 10 peoples were lost due to this disaster. The tsunami impact toward human lives was calculated by using the human instability equation [3] and TUNAMI Two Layer model was applied to simulate the landslide and propagation of tsunami [2]. The simulation results were validated with observations and field measurements data [1]. The result of simulation showed that flow depth of the tsunami reached 0.29-5.83 m with the tsunami velocity about 0.23-7.49 m/s along the shore of Pandeglang Regency. Using Aida Equation for validate simulation results, has K = 0.96733. The results of calculations using the human instability equation show that the value of hazard risk (HR) > 1 because all critical velocity values lower than velocity of simulation. So, it was mean that tsunami waves occurred in Banten especially Pandeglang Regency has high risk impact for the balance of the human body and this condition related with the observation condition that show many victims included people died and injured in this area

Performance Evaluation of DualSPHysics and COMCOT Programs through Numerical Testing for Simulating Tsunami Propagation and Overtopping on Seawalls

A tsunami is a destructive wave that can cause massive damage to coastal infrastructure. One of the disaster mitigation measures that can be chosen is the construction of coastal protection infrastructure, such as a seawall. Seawalls play a crucial role in protecting coastal areas as they can reduce wave energy and minimize the impact of tsunami-induced damage. However, during the 2011 Japan tsunami, the seawall built in Taro city failed as it proved to be less effective in handling the tsunami waves. The research conducted aims to model the propagation and overtopping of tsunami waves on the seawall, initially carried out through physical laboratory experiments, and later transformed into numerical test models using the Smoothed Particle Hydrodynamics (SPH) method and the Cornell Multigrid Coupled Tsunami (COMCOT) model. In this study, the parameters being compared include wave height, wave propagation, and overtopping on the seawall under two scenarios : the run-up of solitary waves on a shore without a seawall and the overtopping condition with a seawall using the Solitary Wave generation type, following the experiments conducted by Huang et al en 2022. Several parameters in the laboratory case study should be considered to expand our understanding of the systematically discussed tsunami propagation and overtopping processes and evaluate the capabilities of the SPH and COMCOT models

Building Vulnerability Analysis Due to Tsunami by Using Probabilistic Tsunami Hazard Assessment (PTHA): A Case Study of Pelabuhan Ratu, Sukabumi

Cities that vulnerable to tsunamis, including the village of Pelabuhan Ratu on the southern coast of West Java, Indonesia, are in dire need of adequate vertical evacuation structures. However, constraints regarding to limited funding and difficulties in finding affordable land have hindered the implementation efforts of such structures in several cities. This research aims to analyze building vulnerability to tsunami disasters and identify buildings that can serve as alternative tsunami evacuation options based on Probabilistic Tsunami Hazard Analysis (PTHA) in Pelabuhan Ratu. The research methodology involves mapping the Modified Building Tsunami Vulnerability (BTV) and connecting the numerical simulation results with fragility curves assumed for the Pelabuhan Ratu area. The numerical simulations were conducted using the Cornell Multi-Grid Coupled Tsunami Model (COMCOT). Various tsunami scenarios triggered by earthquakes with different magnitudes ranging from 8.5 to 9.0, with intervals of 0.1, were considered in the numerical simulations. The research findings indicates high probability of maximum tsunami height reaching 14.85 meters in a return period of 10,000 years, and 51.77 meters in return period of 30,000 years. Based on these results, it was found that a three-story minimarket built with concrete could be used as an evacuation facility in a 10,000-year return period

Probabilistic Analysis of the Tsunami Disaster on the Vulnerability Level of Buildings in Painan City, West Sumatra based on the Earthquake Ratio with the Logic Tree Method

Indonesia is an archipelagic country stretching from Sabang to Merauke and is located at the convergence of the most complex and active tectonic plates in the world, namely Eurasia, Indo-Australia, and the Pacific. One of the regions with a high probability of earthquakes and high tsunamis is the island of Sumatra, which lies between the Eurasian and Indo-Australian plates. Painan city is located in West Sumatra Province, where it is surrounded by three megathrust zones: the Nias-Simeulue segment, Mentawai-Siberut segment, and Mentawai-Pagai segment. These three megathrust zones, namely Nias-Simeulue with an estimated earthquake magnitude of 8.7 Mw, Mentawai-Siberut with an earthquake magnitude of 8.9 Mw, and Mentawai-Pagai with an earthquake magnitude of 8.9 Mw, can potentially cause tsunamis that may reach Painan city. The aim of this study is to investigate the influence of seismic activity level variables and the ratio between large and small earthquakes on tsunami wave height using the logic tree method, assess the tsunami hazard potential using Probabilistic Tsunami Hazard Assessment (PTHA), and evaluate the vulnerability of existing buildings in Painan city. Tsunami simulations in this study were conducted using the Cornell Multigrid Coupled Tsunami (COMCOT) program, which applies the Shallow Water Equation (SWE). Additionally, the Building Tsunami Vulnerability (BTV) equation was used to calculate the vulnerability index of buildings based on their conditions and tsunami wave heights. The calculation of the BTV value for the tsunami height parameter was modified using fragility curves that depict the relationship between force and the probability of tsunami wave damage. From the simulation results, the tsunami height was obtained, which in turn determines the probability of tsunami hazard on buildings with return periods of 1000 and 4000 years. After the simulations, the Building Tsunami Vulnerability (BTV) calculation was performed to determine the vulnerability level of buildings to tsunamis

Implementation of Aceh Health Insurance (Jaminan Kesehatan Aceh) 2013–2021: Has health equity been achieved for all Acehnese after armed conflict?

Aceh Health Insurance (Jaminan Kesehatan Aceh—JKA) has been implemented since 2010 to increase the health equity by covering the health expenses and guaranteeing that all Acehnese are covered regardless of their economic, educational, and social statuses. However, since its implementation, there has been no study on its impact on health quality, particularly regarding the utilization of the main referral hospital (Dr Zainoel Abidin Hospital located in Banda Aceh) and the effects of the geographic accessibility and the number of specialist doctors in each regency/city on hospital utilization. This retrospective study assessed the equity factors during the Aceh Health Insurance implementation and during its integration to National Health Insurance (Jaminan Kesehatan Nasional—JKN) from 2013 to 2021 using data of travel time (time spent for travelling from the origin regency/city of referred patients to the main referral center) and healthcare resources (number of specialist doctors). The data were analyzed using Student’s t-tests, Kolmogorov-Smirnov or Mann-Whitney U test when appropriate. Williamson Index was calculated to determine the disparities of health equity between regencies. Our data indicated the noticeably increase of health facilities utilization since the implantation of Aceh Health Insurance. However, there was no equity in the use of main referral facility by the residents in Aceh - was dominated by residents who lived closer and from more populated regencies/cities. In conclusion, there are accessibility and financial hardship barriers in accessing the health care facilities during the implementation of Aceh Health Insurance that need to be addressed by the government to achieve the health equity for all Acehnese