PENGUKURAN KOEFISIEN AERODINAMIS MODEL-MODEL JEMBATAN BENTANG PANJANG

The objective of this research is to measure aerodynamic coefficients of long-span bridge deck models. Four models with different wind nose (fairings) will be tested using open loop wind tunnel. These replicas are made from glass fiber as major material. Flow-field dynamic similarity is maintained through nondimensional number such as Reynolds number. Determination of aerodynamic coefficients was carried out using balance method whereas aerodynamics forces are measured by strain gages based balance apparatus. The result is presented on graphics of lift coefficient (CL), aerodynamic moment coefficient (CM) and coefficient of drag (CD) as function of angle of attack (a)

WATER WITHIN LIGHTWEIGHT AGGREGATE CONCRETE AND ITS RELATION TO AUTOGENOUS SHRINKAGE

Abstract Autogenous shrinkage of lightweight aggregate concrete (LAC) has been investigated with the aims of studying if water within LAC is effective in preventing autogenous shrinkage as suggested by Bentz’s model. By calculating ratios of water supplied by lightweight aggregate (LA) at various degrees of saturation to water required for maximum hydration and plotting these against ultimate values of autogenous shrinkage, it seems that only when the ratio is high (above 3.5) then the water within LAC supplied from LA is immediately ready to fill the empty pores and in turn, reducing autogenous shrinkage. The case is also confirmed when ratios of total void (porosity) of concrete to total volume of water within concrete are plotted against autogenous shrinkage. Keywords: autogenous shrinkage, Bentz’s model, lightweight aggregate, porosity

THE PREDICTION OF LONG -TERM SHRINKAGE OF LIGHTWEIGHT CONCRETE CONSIDERED TO MAGNITUDE OF SHORT - TERM SHRINKAGE PREDIKSI SUSUT JANGKA PANJANG BETON RINGAN BERDASAR NILAI SUSUT JANGKA PENDEK

The magnitude of long-term shrinkage of lightweight concrete has to be considered in the design of lightweight concrete structure. This research is intended to develop a model for predicting the maginitude of long-term shrinkage of lightweight concrete based on the short-term value. Model of ACI 209 R-92 is used as a reference to start with and then it is verified and modified with the results of more than 9 months shrinkage observation on samples of lightweight concrete having various degrees of saturation of Artificial Lightweight Aggregate (ALWA), water/cement ratios, volume/surface ratios and curing period. The final model may be applied to predict long-term shrinkage of lightweight concrete using data from the observation of shrinkage for 28 days only. Coefficient error of prediction is about 30% Keywords: lightweight concrete, model, prediction, shrinkage Nilai susut jangka panjang dari beton ringan harus diperhitungkan dalam perencanaan struktur beton ringan. Penelitian ini fokus pada pengembangan model prediksi susut jangka panjang beton ringan berdasar nilai susut jangka pendek. Model ACI 209 R-92 digunakan sebagai referensi untuk memulai dan kemudian diverifikasi dan dimodifikasi dengan hasil lebih dari 9 bulan observasi sample susut jangka panjang beton ringan dengan derajat kejenuhan agregeat buatan ringan (Artificial Lightweight Aggregate, ALWA), kadar air dan semen, rasio volume/permukaan, dan waktu perawatan yang berbeda-beda. Model terakhir mungkin bisa dipakai untuk memperkirakan susut jangka panjang beton ringan dengan menggunakan data observasi susut selama 28 hari saja. Angka kesalahan dari prediksi ini sebesar 30%. Kata-kata kunci: beton ringan, model, prediksi, susu

Model dan Pendekatan Fuzzy LogicUntuk Program Pemeliharaan Jembatan Beton

Evaluation of the existing condition of the bridge is the most important part of the bridge maintenance program and is still often depend to a very large degree on the experience, judgment and bridge engineers flexibility, so that resulted to a serious problem due to the nature of subjectivity of assessment. In the process of decision making to determine the type of repairs needed for concrete bridges, one of the key parameter is the condition rating. The reliability of these parameters depends on the reliability and accuracy of information provided bybridge inspectors, who are often influenced imprecision and opinions (biased) personal. Therefore it is necessary to provide a systematic procedure to reduce this weakness. Fuzzy logic provides a natural way to deal with problems that do not have a source of precision in the absence of sharply defined criteria of a class (class) set membership. The set itself is a class of fuzzy objects with membership that has a continuum of gradations (continuum of grades of membership). In the process of bridge inspection, inspectors often must assess the level of severity (severity) of a visual defect with "severe" or "not severe". On the set of non-fuzzy space inspectors is only one response among the above conditions, if the answer is not "severe", yes of course "not severe " is the answer. But in the fuzzy space possible for inspectors to quantify the level of significance between "severe" to "not severe" with a numerical value (numerical rating). Expert System is a system that tries to provide answers to the problem, or clarify the uncertainty which is usually one or more human experts would need to consult. Compared to traditional programming techniques, expert-system approaches provide the added flexibility (and hence easier modifiability) that arises from the ability to model rules as data rather than as code. The resulting software can be a cost - time-effective rapid information for technical evaluation jembatatan maintenance of reinforced concrete. Simultaneously, this software can give recommendations and / or second opinion to support the executive decisions jembatatan maintenance of reinforced concrete

Allocation Priority Determination System for Provincial Bridge Maintenance Fund in Special Region of Yogyakarta By Examining Physical Conditions, Operational Cost and Volume of Traffic

The maintenance of bridges is relatively expensive. Those may lead the maintenance program into a classical problem which is limited of the fund. Therefore, the priority level of bridges maintenance is needed in order to attain an effective and efficient fund usage toward prevalent condition of every bridges in Special Region of Yogyakarta. The objective of this research was to provide the maintenance fund for provincial bridges in Special Region of Yogyakarta. The research covered 10 bridges in Special Region of Yogyakarta. The Assessments method for bridge physical condition was based on guide of Bridge Management System (BMS). As the bridge physical condition was known, the maintenance measure and its needed maintenance cost can be determined. The allocation of fund for each bridge was calculated based on Dynamic Programming Method. The result can be draw that by 5 million rupiah the maintenance fund for each of those 10 bridge of Yogyakarta Special Region is 5 million rupiah for Demak Ijo Bridge, 13 million rupiah for Bedingin Bridge, 10 million rupiah for Denggung Bridge, 5 million rupiah for Ngentak Bridge, 5 million rupiah for Karang Semut Bridge, 8 million rupiah for 2rd Kronggahan Bridge, 7 million rupiah for Besi Bridge, 8 million rupiah for Cebongan Bridge, 2 million rupiah for Kembang Songo Bridge, 2 million rupiah for 1st Kronggahan Bridge. Those allocation system provide 78,7% an average percentage on provincial bridges in Special Region of Yogyakarta.

Integer 1/0 Knapsack Problem Dynamic Programming Approach in Building Maintenance Optimization

The most common problem in urban areas is the high public demand and the limited provision of housing. In meeting the needs of affordable housing for low income communities, the Government of Indonesia implements Rusunawa Project. Object of this research is Pandanarang Rusunawa. Rusunawa Pandanarang is one of the vertical housing in Cilacap that is facing deterioration issue and needs good maintenance management. This study aims at insetting priority and optimizing maintenance plan due to limited funds (limited budget) and the amount of damage that must be repaired.This study uses one of the optimization methods of Dynamic Programing on the application of Integer 1/0 Knapsack Problem, to determine an schedule the maintenance activities. The Criteria that are used such as: the level of building components damage and the level of occupants participation. In the first criterion, the benefit (p) is the percentage of damage that is fixed with the cost (w). While on the second criterion, the benefit (p) is the percentage of occupant participation rate on the maintenance activities with the cost (w). For the budget of Rp 125.000.000, 00, it was obtained from the simulation that the value of the optimum solution on the first criterion at the 7th stage of 71.88% with total cost Rp 106.000.000, 00. At the second criterion, the value of the optimum solution at the 7th stage of 89.29% with total cost Rp 124.000.000, 00

MEWUJUDKAN RESILIENSI MASYARAKAT TERHADAP BENCANA GEMPA BUMI MELALUI EDUKASI HUNIAN TAHAN GEMPA

Abstrak: Dalam satu dekade terakhir, pembangunan kawasan hunian baru di Desa Tohudan meningkat, baik yang dilakukan oleh pengembang perumahan maupun masyarakat secara mandiri. Praktik konstruksi yang dilakukan masyarakat secara mandiri seringkali tidak melibatkan tenaga ahli konstruksi melainkan hanya tenaga terampil (pemborong, mandor, tukang, dsb). Kondisi ini diperparah dengan minimnya pengetahuan masyarakat mengenai persyaratan teknis yang harus dipenuhi agar bangunan aman terhadap gempa. Untuk itu, kegiatan pengabdian kepada masyarakat ini dilaksanakan dengan tujuan untuk memberikan edukasi kepada masyarakat mengenai bagaimana melaksanakan praktik konstruksi yang baik sesuai dengan standar teknis yang berlaku. Kegiatan ini dilaksanakan bersama mitra pemerintah Desa Tohudan melalui penyuluhan dan dibagi dalam tiga tahap yaitu identifikasi permasalahan mitra, persiapan, dan pelaksanaan. Kegiatan ini diikuti oleh 14 peserta dengan nilai rerata pre-test 26 (rentang nilai 10-40) dan nilai rerata post-test 66 (rentang nilai 50-100). Terlihat bahwa kegiatan ini berdampak pada peningkatan pemahaman masyarakat mengenai bagaimana membangun rumah yang aman terhadap gempa. Lebih lanjut, dengan berbekal pengetahuan yang diperoleh dari kegiatan ini dan terlaksananya praktik konstruksi yang baik sesuai dengan standar teknis yang berlaku, dapat mendorong terwujudnya resiliensi masyarakat terhadap bencana gempa bumi.Abstract: In the last decade, new residential area construction in Tohudan Village has increased, carried out by property developers or community independently. Construction practices carried out by the community independently often do not involve construction experts but only skilled workers (contractors, foremen, builders, etc.). This condition is exacerbated by the lack of public knowledge of the technical requirements that must be met so that buildings are safe against earthquakes. For this reason, this community service activity is carried out to educate the community on how to implement good construction practices under applicable technical standards. This activity was carried out with the Tohudan Village government through counselling and was divided into three stages: identification of partner problems, preparation, and implementation. This activity was attended by 14 participants with a pre-test mean score of 26 (range 10-40) and a post-test mean score of 66 (range 50-100). It can be seen that this activity has an impact on increasing public understanding of how to build earthquake-safe houses. Furthermore, armed with the knowledge gained from this activity and the implementation of good construction practices under applicable technical standards, it can encourage the realization of community resilience to earthquake disasters

Creep Behavior of Fiber Reinforced Mortars and Its Effect to Reduce the Differential Shrinkage Stress

This research aims to develop durable repair materials that can resist shrinkage cracking by exploring the role of creep in reducing shrinkage stress. In this regard, the creep effect can only be quantified if an accurate creep prediction model and theoretical analysis of the shrinkage stress in the patch repair system exist. For this purpose, the research was carried out in the following sequences: first, the research investigated the short-term creep of the patch repair materials containing accelerator and micro-synthetic fibers in the 0.00–0.12% volume fraction range. This short-term creep was measured on five-cylinder specimens (having a diameter of 75 mm and a height of 275 mm). Three specimens were used to determine the deformation of the repair material under unloading conditions, while those remaining were used to determine the total deformation under loading conditions. The amount of creep deformation was determined by taking away the unloaded (shrinkage) and instantaneous (elastic) deformations from the total deformation of the loaded specimens. Secondly, a modified prediction model of ACI 209R-08 is introduced to accurately capture the rate and magnitude of the observed creep of the repair materials. Finally, a formulated theoretical analysis of shrinkage stress in the patch repair system was proposed to examine how creep potentially reduces the repair material's cracking tendency. The results show that the asymptotic value of the creep curve is attained at an earlier age and that its magnitude is greater than that of most concrete. The modified ACI 209R-08 prediction model can closely estimate the repair materials' creep behavior. The best-fit line, residual values, and coefficient of error analyses confirm the modified model's prediction accuracy. The analysis of tensile stress development in the repair layer suggests that creep can reduce stress by up to 50%. With such a reduction, the repair material is expected to be durable in resisting shrinkage and cracking tendency. Doi: 10.28991/CEJ-2023-09-08-014 Full Text: PD

EVALUASI AWAL RESIKO SEISMIK BANGUNAN GEDUNG RUSUNAWA

Tingginya kebutuhan masyarakat atas hunian dan terbatasnya lahan di perkotaan,mengharuskan pemerintah mengambil kebijakan mendorong pembangunan perumahan danpermukiman ke arah vertikal untuk daerah yang berkepadatan tinggi. Pada tahun 2006 KabupatenCilacap mendapat alokasi pembangunan Rusunawa. Cilacap merupakan salah satu daerah yang rawanterhadap gempa. Ini terlihat dari beberapa gempa yang terjadi beberapa tahun terakhir. Dengan latarbelakang daerah Cilacap yang rawan terhadap gempa dan berada di daerah pesisir, kebutuhan akananalisis yang rasional dan perkiraan-perkiraan objektif yang memiliki resiko harta dan kehidupanbukan hanya kebutuhan akademis. Dengan demikian evaluasi keandalan bangunan diperlukan secaraberkala untuk meminimalisasi kerugian yang diakibatkan oleh kerusakan bangunan. Evaluasi berkalakeandalan bangunan dapat dilakukan dengan Rapid Visual Screening of Buildings yang selanjutnyadigunakan untuk menentukan Performance Levels Building. Evaluasi secara cepat dilakukan denganRapid Visual Screening (RVS) berdasarkan FEMA (Federal Emergency Management Agency) 154yang dikembangkan di Amerika Serikat. Proses skrening yang dilakukan di Rusunawa Cilacapmendapatkan skor akhir 0,7 Skor Akhir 0,7 berarti ada peluang 1 dari 100,7, atau 1 dari 5 bangunanakan runtuh jika gempa tersebut terjadi. Data base tentang bangunan diperlukan untuk memudahkanrencana dan tahapan rehabilitasi bangunan.\Kata kunci : Resiko seismik, Rapid Visual Screening, Rusunaw

Analytical Hierarchy Process (AHP), Fuzzy AHP, and TOPSIS for Determining Bridge Maintenance Priority Scale in Banjarsari, Surakarta

Data on 2015 [9] show that less than 50 percent of provincial and local level bridges in Central Java are in good condition. In the other hand, it has been reported that local bridges in the city of Surakarta have been deteriorated and damaged. The maintenance and rehabilitation action often done based solely on incidental reports without systematic planning. Analytical Hierarchy Process, Fuzzy Analytical Hierarchy Process, and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) were used to compare the priority scale of bridge management in Kecamatan (District) Banjarsari, Surakarta. Bridge Management System 1993 (BMS 1993) standard was used to quantify bridge damage condition by means of direct visual observation. Scores used in this 3 different analysis were determined by comparing aforementioned 2 criteria and 9 sub criteria. Accordingly, criteria and subcriteria defined in this paper were based on the standard. The criteria employed were bridge damage condition and average daily traffic (ADT). Bridge condition criteria were then divided further into sub criteria; i.e. river stream, safety support building, foundation, pier, girder system, parapet, floor system, expansion joint, and other property. From 11 bridges considered in this study, Maris Bridge has the highest pirority determined in 3 different methods. AHP and TOPSIS methods show Ringin Semar Bridge the lowest priority to maintain. On the other hand, Fuzzy AHP determines Balapan Bridge as the lowest order. Keyword: Bridge Management, BMS 1993, AHP, FAHP, TOPSIS