Algorithm to Estimate the Capacity Reserve of Existing Masonry Arch Railway Bridges

Most railway masonry arch bridges were designed according to codes that predate the 1950s; therefore, assessing their load-carrying capacity to comply with current codes is of the utmost importance. Nonetheless, acquiring the necessary information to conduct in-depth analyses is expensive and time consuming. In this article, we propose an expeditious procedure to conservatively assess the Load Rating Factor of masonry arch railway bridges based on a minimal set of information: the span, rise-to-span ratio, and design code. This method consists in applying the Static Theorem to determine the most conservative arch geometry compatible with the original design code; assuming this conservative geometrical configuration, the load rating factor, with respect to a different design load, is estimated. Using this algorithm, a parametric analysis was carried out to evaluate the Load Rating Factor of old arch bridges in respect of the modern freight load of the Trans-European Conventional Rail System, for different spans, rise-to-span ratios, and original design codes. The results are reported in easy-to-use charts, and summarized in simple, practical rules, which can help railway operators to rank their bridges based on capacity deficit.

Finite Element Model-Based Weight-Over Process Philosophy for Bridge Loading Capacity Evaluation and Rating Factor Estimation

Existing rating methods estimate bridge loading capacity and demand from secondary actions due to live loads in the primary structural components. In these methods, uniaxial yielding stress is traditionally used to detect component capacity using either stress quantities or shear-moment actions to compute the capacity demand of the bridge. These approximations can lead to uncertainties in load capacity estimation. This article presents the weight-over process (WOP), a novel computer-aided approach to bridge loading capacity evaluation based on tonnage and rating factor estimation. WOP is expected to capture different forms of failure in a more general manner than existing methods. In WOP, a bridge finite element model (FEM) is discretized into many sections and element sets, each containing a single material type, and each assigned a suitable 3D failure criterion. Then, factored gross vehicle weights (GVWs) are incrementally imposed on the bridge FEM with those predefined ultimate unfavored loading scenarios in a manner similar to proof load testing. WOP code runs nonlinear analysis at each increment until a stopping criterion is met. Two representative bridges were selected to confirm WOP’s feasibility and efficacy. The results showed that WOP-predicted values at the interior girders were between those of the conventional AASHTO and the nondestructive testing (NDT) strain measurement methods. That may put WOP in a favorable zone as a new method that is less conservative than AASHTO but more conservative than real NDT testing.

Nghiên cứu hiệu chỉnh mô hình đánh giá khả năng chịu tải công trình cầu dựa vào số liệu đo đạc thực nghiệm trên mô hình toàn cầu

Tuổi thọ và khả năng khai thác hoạt tải của công trình cầu trên thực tế có sự sai khác nhất định so với kết quả tính toán thiết kế. Do vậy, công tác đánh giá khả năng chịu tải thực tế công trình cầu đóng vai trò quan trọng đối với công trình cầu mới xây dựng xong và đặc biệt quan trọng đối với các công trình cầu cũ đã qua quá trình khai thác, sử dụng lâu dài. Bài báo trình bày phương pháp hiệu chỉnh mô hình phân tích kết cấu cầu thông qua các thông số độ cứng của hệ dầm mặt cầu, dựa vào các kết quả đo đạc phản ứng động của cầu dưới tác dụng của hoạt tải thử nghiệm trên mô hình toàn cầu (full scale model). Mô hình kết cấu cầu sau khi hiệu chỉnh sẽ phù hợp với ứng xử thực tế của công trình cầu và được dùng để đánh giá khả năng chịu tải thông qua thông số RF (rating factor).

Analisis Nilai Kapasitas Beton Prategang Tipe-I Jembatan Cimanuk Maktal

Jembatan Cimanuk Maktal merupakan salah satu prasana untuk dilewati orang dan transfortasi yang melewati sungai Cimanuk. Jembatan ini merupakan konstruksi baru sehingga perlu pengecekan terhadap nilai kapasitan yang dimiliki jembatan tersebut. Jembatan Cimanuk Maktal merupakan jembatan balok prategang tipe-I. Peneliti melakukan analisa perhitungan pada eksisting jembatan menggunakan metode rating factor (RF) pada saat inventory dan operating. Untuk perhitungan rating factor mengacu pada Pedoman Penentuan Nilai Kapasitas Jembatan dari Dirjen Bina Marga, dan untuk perhitungan analisa penampang dipandu dari Perencanaan Struktur Beton Jembatan dari RSNI-12-2004. Dari penelitian tersebut didapat bahwa jembatan tersebut dapat dikatakan aman dan sudah layak digunakan, karena nilai kapasitas yang didapat dari analisa perhitungan melebihi dari nilai kapasitas ijin. Dimana, nilai RF berdasarkan Inventory akibat momen 1,7 > 1 dan akibat gaya geser 1,3 > 1. Juga nilai RF berdasarkan Operating akibat momen 2,02 > 1 dan akibat gaya geser 1,9 > 1.

Penentuan Tenaga Kerja Optimal pada Packaging Kopi dengan Menggunakan Analisis Beban Kerja Metode Work Sampling

The effectiveness, efficiency, and productivity of the company are very much determined by the workload. By knowing the workload, a company can find out the optimum number of workers needed to meet the target. This is also important for the Indonesian Coffee and Cocoa Research Center, especially in the processing of coffee in the packaging section. Therefore a workload analysis will be carried out using the Work Sampling Method. From the results of the work sampling method, it can be seen that worker productivity is 0.90697, as well as a rating factor of 0.09 and an allowance of 22.With these results it can be calculated that the standard time needed by workers in coffee packaging is 10.98 minutes and the optimum number of workers required 2.06 people.

EVALUASI NILAI SISA KAPASITAS JEMBATAN VOIDED SLAB WAY BAKO I BERDASARKAN PERATURAN PEMBEBANAN SNI 1725-2016 dan PPJJR No. 12/1970

Jembatan dapat mengalami kegagalan struktur karena berbagai macam faktor eksternal. Keadaan Jembatan Way Bako I yang mengalami lendutan cukup besar saat kendaraan melintas dan permukaan aspal yang selalu rusak mengindikasikan adanya potensi kegagalan struktur jembatan. Mengingat kegagalan struktur ini berbahaya bagi penggunanya, maka diperlukan langkah evaluasi sehingga dapat diketahui nilai sisa kapasitas jembatan dan dihindari kegagalan strukturnya. Evaluasi pada Jembatan ini menggunakan metode rating factor (RF) mengacu kepada Pedoman Penentuan Nilai Sisa Kapasitas jembatan dari Dirjen Bina Marga dengan melakukan analisis terhadap kondisi harian (inventory) dan kondisi khusus (operating). Berdasarkan pengamatan lapangan dan perhitungan data penelitian, Jembatan Way Bako I mengalami kerusakan non struktur maupun struktur. Berdasarkan analisis RF menurut SNI 1725-2016 dan PPJJR No. 12/1970 didapat hasil bahwa kapasitas momen pada inventory rating factor dan operating rating factor tidak aman karena memiliki nilai RF < 1. Sedangkan kapasitas geser pada inventory rating factor dan operating rating factor aman karena memiliki nilai RF > 1. Dengan demikian maka Jembatan Way Bako I memerlukan perbaikan struktur.

Challenging the Industry Practices of Temperature Distribution, SIF and its Effects on Piping Design

The piping, welding and its fittings contributes to around 25–35% of the total material [1] of any process plant. The quantity of the piping and fittings required in critical pipes (lines) is largely influenced by the flexibility requirements to comply with applicable codes. Since the pressure and weight driven stresses are primary in nature and taken care by the thickness & supports respectively. The Secondary stresses are mainly caused due to temperature and determines the route of the pipe. Unfortunately, there is no sufficient awareness amongst the Process engineers, who dictate the temperature, about the effect of temperature (listed in line list) on the plant cost. To make the situation worse, very often the pipe stress engineers follow thumb rules, conservative design basis while applying temperature to pipes without questioning process engineers the basis and without having experimental evidences which in turn ends up adding to the cost, labor and time of the plant. Another factor influencing the ‘flexibility need’ is ‘Stress Intensification Factor’ which, as well, incorrectly multiplied by conservative numbers, especially in case of 45° branch fittings. Even ‘Flange leakage analysis’ needs to be performed to ensure safety of the plant. This paper challenges the mis-concepts in temperature distribution of a piping system by analyzing a real-life problem. Also, it provides the actual temperature measurements and compares it with theoretical values. At the end it provides a ‘Temperature de-rating factor, @(Taa)’ which can be used to derive actual expected temperature distribution. Further this paper provides a table to get the actual SIF of Tee and Fittings obtained by FEA. At the end it provides comparison between the results obtained by present industry practices against practical analysis and its effect on cost.

Pengukuran waktu baku dan analisis beban kerja untuk menentukan jumlah optimal tenaga kerja pada proses cetak produk lipstick

PT Astoria Prima is a manufacturing company that runs in the field of cosmetic products, currently the company does not yet have a perfect time standard to be applied in the production process. In this study will take data on the production process of lipstick filling in which the filling process of production has hours of work and uncertain results due to the absence of standard time and the exact amount of labor. This study tries to measure the workload of a lipstick fill operator with a work sampling method. From the measurements obtained different standard times; operator 1 = 0.469 minutes, operator 2 = 0.475 minutes, operator 3 = 0.483 minutes, operator 4 = 0.465 minutes, operator 5 = 0.466 minutes, operator 6 = 0.501 minutes and operator 7 = 0.5 minutes. Different standard time because the job description, rating factor and allowance each operator different. From the standard time that has been obtained, it can be seen the number of operators who should be employed to complete the process from the beginning to finish lipstick filling is 7 operators. The average percentage or workload of employees obtained based on the results of data analysis is 104.52% that the workload obtained by the operator is sufficient in accordance with workload that can be received by a worker.

Analisis Penentuan Waktu Satandar Pada Proses Outbond Bagasi di PT Angkasa Pura II

Time Study merupakan suatu usaha untuk menentukan lamanya waktu kerja yang diperlukan oleh seorang operator untuk menyelesaikan suatu pekerjaan (Niebel, 1988). Pengukuran waktu secara garis besar terdiri dari 2 jenis, yaitu pengukuran waktu langsung dan pengukuran waktu tidak langsung. Untuk menghitung waktu standar perlu dihitung waktu siklus rata-rata yang disebut dengan waktu terpilih, rating factor, waktu normal dan kelonggaran (allowance). dilakukan untuk meramalkan kejadian yang terjadi pada masa depan. Penelitian mengenai peramlan Dengan demikian waktu efektif atau waktu standar yang mampu dilakukan oleh setiap Ground Handling dalam melakukan penyediaan jasa sangat dibutuhkan oleh penumpang. Penyimpangan layanan bagasi tersebut biasa terjadi pada saat penumpang tiba di stasiun tujuan akhir atau saat post flight services, hal tersebut bisa menjadi salah satu tolak ukur kinerja suatu Ground Handling, baik atau tidaknya dalam memberikan layanan kepada penumpang. Kasus-kasus yang berhubungan dengan penyimpangan bagasi tersebut masih menggunakan proses manual yang pada akhirnya memakan waktu yang cukup lama. Maka dengan demikian, penggunaan metode Time Study yang dilakukan oleh penulis berguna untuk menganalisis penyebab terjadinya keterlambatan dan juga mendapatkan solusi yang tepat agar proses outbound ini berjalan sesuai dengan standar kerja. Setelah mendapatkan waktu baku selama 37 menit dari hasil perhitungan maka dilakukan perhitungan jumlah tenaga kerja optimum pada proses outbound untuk menentukan perencanaan kebutuhan tenaga kerja, dengan cara waktu baku dikali dengan beban kerja dan kemudian dibagi dengan waktu kerja efektif yang telah ditetapkan oleh perusahaan. Maka didapatkan penambahan tujuh orang yang semula hanya 5 orang, penambahan tenaga terjadi pada bagian loading ke BTT dan pengecekan kondisi bagasi serta cek manifest bagasi masing – masing yaitu 1 tenaga kerja